xmpp.chapril.org-ejabberd/doc/guide.tex

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%% Various
\newcommand{\bracehack}{\def\{{\char"7B}\def\}{\char"7D}}
\newcommand{\titem}[1]{\item[\bracehack\texttt{#1}]}
\newcommand{\ns}[1]{\texttt{#1}}
\newcommand{\jid}[1]{\texttt{#1}}
\newcommand{\option}[1]{\texttt{#1}}
\newcommand{\poption}[1]{{\bracehack\texttt{#1}}}
\newcommand{\node}[1]{\texttt{#1}}
\newcommand{\term}[1]{\texttt{#1}}
\newcommand{\shell}[1]{\texttt{#1}}
\newcommand{\ejabberd}{\texttt{ejabberd}}
\newcommand{\Jabber}{Jabber}

%% Modules
\newcommand{\module}[1]{\texttt{#1}}
\newcommand{\modadhoc}{\module{mod\_adhoc}}
\newcommand{\modannounce}{\module{mod\_announce}}
\newcommand{\modcaps}{\module{mod\_caps}}
\newcommand{\modconfigure}{\module{mod\_configure}}
\newcommand{\moddisco}{\module{mod\_disco}}
\newcommand{\modecho}{\module{mod\_echo}}
\newcommand{\modirc}{\module{mod\_irc}}
\newcommand{\modlast}{\module{mod\_last}}
\newcommand{\modlastodbc}{\module{mod\_last\_odbc}}
\newcommand{\modmuc}{\module{mod\_muc}}
\newcommand{\modmuclog}{\module{mod\_muc\_log}}
\newcommand{\modoffline}{\module{mod\_offline}}
\newcommand{\modofflineodbc}{\module{mod\_offline\_odbc}}
\newcommand{\modprivacy}{\module{mod\_privacy}}
\newcommand{\modprivacyodbc}{\module{mod\_privacy\_odbc}}
\newcommand{\modprivate}{\module{mod\_private}}
\newcommand{\modprivateodbc}{\module{mod\_private\_odbc}}
\newcommand{\modproxy}{\module{mod\_proxy65}}
\newcommand{\modpubsub}{\module{mod\_pubsub}}
\newcommand{\modregister}{\module{mod\_register}}
\newcommand{\modroster}{\module{mod\_roster}}
\newcommand{\modrosterodbc}{\module{mod\_roster\_odbc}}
\newcommand{\modservicelog}{\module{mod\_service\_log}}
\newcommand{\modsharedroster}{\module{mod\_shared\_roster}}
\newcommand{\modstats}{\module{mod\_stats}}
\newcommand{\modtime}{\module{mod\_time}}
\newcommand{\modvcard}{\module{mod\_vcard}}
\newcommand{\modvcardldap}{\module{mod\_vcard\_ldap}}
\newcommand{\modvcardodbc}{\module{mod\_vcard\_odbc}}
\newcommand{\modversion}{\module{mod\_version}}

%% Contributed modules
\usepackage{ifthen}
\newboolean{modhttpbind}
\newcommand{\modhttpbind}{\module{mod\_http\_bind}}
\newboolean{modhttpfileserver}
\newcommand{\modhttpfileserver}{\module{mod\_http\_fileserver}}
\include{contributed_modules}

%% Common options
\newcommand{\iqdiscitem}[1]{\titem{iqdisc} \ind{options!iqdisc}This specifies 
the processing discipline for #1 IQ queries (see section~\ref{modiqdiscoption}).}
\newcommand{\hostitem}[1]{
  \titem{host} \ind{options!host} This option defines the Jabber ID of the
  service. If the \texttt{host} option is not specified, the Jabber ID will be the
  hostname of the virtual host with the prefix `\jid{#1.}'. The keyword "@HOST@"
  is replaced at start time with the real virtual host name.
}

%% Title page
\include{version}
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\title{
{\rule{\larg}{1mm}}\vspace{7mm}
\begin{tabular}{r}
    {\huge {\bf ejabberd \version\ }} \\
    \\
    {\huge Installation and Operation Guide}
\end{tabular}\\
\vspace{2mm}
{\rule{\larg}{1mm}}
\vspace{2mm} \\
\begin{tabular}{r}
    {\large  \bf \today}
\end{tabular}\\
\vspace{5.5cm}
}
\author{\begin{tabular}{p{13.7cm}}
ejabberd Development Team
\end{tabular}}
\date{}


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\begin{document}

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%%  \begin{quotation}\textit{I can thoroughly recommend ejabberd for ease of setup ---
%%  Kevin Smith, Current maintainer of the Psi project}\end{quotation}

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\tableofcontents{}

% Input introduction.tex
\input{introduction}

\chapter{Installing \ejabberd{}}

\section{Installing \ejabberd{} with Binary Installer}

Probably the easiest way to install an \ejabberd{} instant messaging server
is using the binary installer published by Process-one. 
The binary installers of released \ejabberd{} versions 
are available in the Process-one \ejabberd{} downloads page:
\ahrefurl{http://www.process-one.net/en/ejabberd/downloads}

The installer will deploy and configure a full featured \ejabberd{}
server and does not require any extra dependencies.

In *nix systems, remember to set executable the binary installer before starting it. For example:
\begin{verbatim}
  chmod +x ejabberd-2.0.0_1-linux-x86-installer.bin
  ./ejabberd-2.0.0_1-linux-x86-installer.bin
\end{verbatim}

The installer generates desktop shortcuts to start and stop ejabberd.

The Windows installer also adds ejabberd as a system service,
and a shortcut to a debug console for experienced administrators.
You can start ejabberd using the shortcut or the Windows service. 
Note that the Windows service is a feature still in development, 
and for example it doesn't keep track of changes made manually in ejabberdctl.cfg.
If you want ejabberd to be started automatically at boot time, 
go to the Windows service settings and set ejabberd to be automatic started.

On a Linux system, if you want ejabberd to start as daemon at boot time, 
copy \term{ejabberd.init} from the bin directory to something like \term{/etc/init.d/ejabberd}
(depending on your distribution) and call \term{/etc/inid.d/ejabberd start} to start it.

The \term{ejabberdctl} administration script is included in the \term{bin} directory.
Please refer to the section~\ref{ejabberdctl} for details about \term{ejabberdctl},
and configurable options to fine tune the Erlang runtime system.

\section{Installing \ejabberd{} with Operating System specific packages}

Some Operating Systems provide a specific \ejabberd{} package adapted to 
the system architecture and libraries.
It usually also checks dependencies 
and performs basic configuration tasks like creating the initial
administrator account. Some examples are Debian and Gentoo. Consult the
resources provided by your Operating System for more information.

Usually those packages create a script like \term{/etc/init.d/ejabberd}
to start and stop \ejabberd{} as a service at boot time.

\section{Installing \ejabberd{} with CEAN}

\footahref{http://cean.process-one.net/}{CEAN}
(Comprehensive Erlang Archive Network) is a repository that hosts binary
packages from many Erlang programs, including \ejabberd{} and all its dependencies.
The binaries are available for many different system architectures, so this is an
alternative to the binary installer and Operating System's \ejabberd{} packages.

You will have to create your own \ejabberd{} start
script depending of how you handle your CEAN installation. 
The default \term{ejabberdctl} script is located
into \ejabberd{}'s priv directory and can be used as an example.

\section{Installing \ejabberd{} from Source Code}
\label{installation}
\ind{install}

The canonical form for distribution of \ejabberd{} stable releases is the source code package.
Compiling \ejabberd{} from source code is quite easy in *nix systems, 
as long as your system have all the dependencies.

\subsection{Requirements}
\label{installreq}
\ind{installation!requirements}

To compile \ejabberd{} on a `Unix-like' operating system, you need:
\begin{itemize}
\item GNU Make
\item GCC
\item Libexpat 1.95 or higher
\item Erlang/OTP R10B-9 up to R11B-5. Erlang R12 releases are not yet officially supported, and are not recommended for production servers.
\item OpenSSL 0.9.6 or higher, for STARTTLS, SASL and SSL encryption. Optional, highly recommended.
\item Zlib 1.2.3 or higher, for Stream Compression support (XEP-0138). Optional.
\item GNU Iconv 1.8 or higher, for the IRC Transport (mod\_irc). Optional. Not needed on systems with GNU Libc.
\end{itemize}

\subsection{Download Source Code}
\label{download}
\ind{install!download}

Released versions of \ejabberd{} are available in the Process-one \ejabberd{} downloads page:
\ahrefurl{http://www.process-one.net/en/ejabberd/downloads}

\ind{Subversion repository}
Alternatively, the latest development version can be retrieved from the Subversion repository using this command:
\begin{verbatim}
  svn co http://svn.process-one.net/ejabberd/trunk ejabberd
\end{verbatim}


\subsection{Compile}
\label{compile}
\ind{install!compile}

To compile \ejabberd{} execute the commands:
\begin{verbatim}
  ./configure
  make
\end{verbatim}

The build configuration script provides several parameters.
To get the full list run the command:
\begin{verbatim}
  ./configure --help
\end{verbatim}

Some options that you may be interested in modifying:
\begin{description}
	\titem{--prefix=/} 
	Specify the path prefix where the files will be copied when running the make install command.

	\titem{--enable-pam} 
	Enable the PAM authentication method.

	\titem{--enable-odbc or --enable-mssql}
	Required if you want to use an external database.
	See section~\ref{database} for more information.

	\titem{--enable-full-xml} 
	Enable the use of XML based optimisations.
	It will for example use CDATA to escape characters in the XMPP stream. 
	Use this option only if you are sure your Jabber clients include a fully compliant XML parser.

	\titem{--disable-transient-supervisors}
	Disable the use of Erlang/OTP supervision for transient processes. 
\end{description}


\subsection{Install}
\label{install}
\ind{install!install}

To install \ejabberd{} in the destination directories, run the command:
\begin{verbatim}
  make install
\end{verbatim}
Note that you may need to have administrative privileges in the system.

The files and directories created are, by default:
\begin{description}
	\titem{/etc/ejabberd/} Configuration files:
		\begin{description}
			\titem{ejabberd.cfg} ejabberd configuration file
			\titem{ejabberdctl.cfg} Configuration file of the administration script
			\titem{inetrc} Network DNS configuration
		\end{description}
	\titem{/sbin/ejabberdctl} Administration script
	\titem{/var/lib/ejabberd/}
		\begin{description}
			\titem{.erlang.cookie} Erlang cookie file
			\titem{db} Mnesia database spool files
			\titem{ebin} Binary Erlang files (*.beam)
			\titem{priv}
				\begin{description}
					\titem{lib} Binary system libraries (*.so)
					\titem{msgs} Translated strings (*.msgs)
				\end{description}
		\end{description}
	\titem{/var/log/ejabberd/} Log files (see section~\ref{logfiles}):
		\begin{description}
			\titem{ejabberd.log} ejabberd service log
			\titem{sasl.log} Erlang/OTP system log
		\end{description}
\end{description}


\subsection{Start}
\label{start}
\ind{install!start}

You can use the \term{ejabberdctl} command line administration script to start and stop \ejabberd{}.

Usage example:
\begin{verbatim}
$ ejabberdctl start

$ ejabberdctl status
Node ejabberd@localhost is started. Status: started
ejabberd is running

$ ejabberdctl stop
\end{verbatim}
Please refer to the section~\ref{ejabberdctl} for details about \term{ejabberdctl},
and configurable options to fine tune the Erlang runtime system.

\subsection{Specific Notes for BSD}
\label{bsd}
\ind{install!bsd}

The command to compile \ejabberd{} in BSD systems is:
\begin{verbatim}
  gmake
\end{verbatim}


\subsection{Specific Notes for Microsoft Windows}
\label{windows}
\ind{install!windows}

\subsubsection{Requirements}
\label{windowsreq}

To compile \ejabberd{} on a Microsoft Windows system, you need:
\begin{itemize}
\item MS Visual C++ 6.0 Compiler
\item \footahref{http://erlang.org/download.html}{Erlang/OTP R11B-5 or higher}
\item \footahref{http://sourceforge.net/project/showfiles.php?group\_id=10127\&package\_id=11277}{Expat 2.0.0 or higher}
\item
\footahref{http://www.gnu.org/software/libiconv/}{GNU Iconv 1.9.2}
(optional)
\item \footahref{http://www.slproweb.com/products/Win32OpenSSL.html}{Shining Light OpenSSL 0.9.8d or higher}
(to enable SSL connections)
\item \footahref{http://www.zlib.net/}{Zlib 1.2.3 or higher}
\end{itemize}


\subsubsection{Compilation}
\label{windowscom}

We assume that we will try to put as much library as possible into \verb|C:\sdk\| to make it easier to track what is install for \ejabberd{}.

\begin{enumerate}
\item Install Erlang emulator (for example, into \verb|C:\sdk\erl5.5.5|).
\item Install Expat library into \verb|C:\sdk\Expat-2.0.0|
  directory.

  Copy file \verb|C:\sdk\Expat-2.0.0\Libs\libexpat.dll|
  to your Windows system directory (for example, \verb|C:\WINNT| or
  \verb|C:\WINNT\System32|)
\item Build and install the Iconv library into the directory
  \verb|C:\sdk\GnuWin32|.

  Copy file \verb|C:\sdk\GnuWin32\bin\lib*.dll| to your
  Windows system directory (more installation instructions can be found in the
  file README.woe32 in the iconv distribution).

  Note: instead of copying libexpat.dll and iconv.dll to the Windows
  directory, you can add the directories
  \verb|C:\sdk\Expat-2.0.0\Libs| and
  \verb|C:\sdk\GnuWin32\bin| to the \verb|PATH| environment
  variable.
\item Install OpenSSL in \verb|C:\sdk\OpenSSL| and add \verb|C:\sdk\OpenSSL\lib\VC| to your path or copy the binaries to your system directory.
\item Install ZLib in \verb|C:\sdk\gnuWin32|. Copy 
  \verb|C:\sdk\GnuWin32\bin\zlib1.dll| to your system directory. If you change your path it should already be set after  libiconv install. 
\item Make sure the you can access Erlang binaries from your path. For example: \verb|set PATH=%PATH%;"C:\sdk\erl5.5.5\bin"|
\item Depending on how you end up actually installing the library you might need to check and tweak the paths in the file configure.erl.
\item While in the directory \verb|ejabberd\src| run:
\begin{verbatim}
configure.bat
nmake -f Makefile.win32
\end{verbatim}
\item Edit the file \verb|ejabberd\src\ejabberd.cfg| and run
\begin{verbatim}
werl -s ejabberd -name ejabberd
\end{verbatim}
\end{enumerate}

%TODO: how to compile database support on windows?


\section{Create a Jabber Account for Administration}
\label{initialadmin}

You need a Jabber account and grant him administrative privileges
to enter the \ejabberd{} Web Admin:
\begin{enumerate}
\item Register a Jabber account on your \ejabberd{} server, for example \term{admin1@example.org}. 
  There are two ways to register a Jabber account:
  \begin{enumerate}
  \item Using \term{ejabberdctl}\ind{ejabberdctl} (see section~\ref{ejabberdctl}):
    \begin{verbatim}
% ejabberdctl register admin1 example.org FgT5bk3
\end{verbatim} 
  \item Using a Jabber client and In-Band Registration (see section~\ref{modregister}).
  \end{enumerate}
\item Edit the \ejabberd{} configuration file to give administration rights to the Jabber account you created:
  \begin{verbatim}
  {acl, admins, {user, "admin1", "example.org"}}.
  {access, configure, [{allow, admins}]}.
\end{verbatim} 
  You can grant administrative privileges to many Jabber accounts,
  and also to accounts in other Jabber servers.
\item Restart \ejabberd{} to load the new configuration.
\item Open the Web Admin (\verb|http://server:port/admin/|) in your
  favourite browser. Make sure to enter the \emph{full} JID as username (in this
  example: \jid{admin1@example.org}. The reason that you also need to enter the
  suffix, is because \ejabberd{}'s virtual hosting support.
\end{enumerate}

\section{Upgrading \ejabberd{}}

To upgrade an ejabberd installation to a new version,
simply uninstall the old version, and then install the new one.
Of course, it is important that the configuration file 
and Mnesia database spool directory are not removed.

\ejabberd{} automatically updates the Mnesia table definitions at startup when needed.
If you also use an external database for storage of some modules,
check if the release notes of the new ejabberd version
indicates you need to also update those tables.


\chapter{Configuring \ejabberd{}}
\section{Basic Configuration}
\label{basicconfig}
\ind{configuration file}

The configuration file will be loaded the first time you start \ejabberd{}. The
content from this file will be parsed and stored in the internal \ejabberd{} database. Subsequently the
configuration will be loaded from the database and any commands in the
configuration file are appended to the entries in the database. 

Note that \ejabberd{} never edits the configuration file. 
So, the configuration changes done using the Web Admin
are stored in the database, but are not reflected in the configuration file.
If you want those changes to be use after \ejabberd{} restart, you can either
edit the configuration file, or remove all its content.

The configuration file contains a sequence of Erlang terms. Lines beginning with a
\term{`\%'} sign are ignored. Each term is a tuple of which the first element is
the name of an option, and any further elements are that option's values. If the
configuration file do not contain for instance the `hosts' option, the old
host name(s) stored in the database will be used.


You can override the old values stored in the database by adding next lines to
the configuration file:
\begin{verbatim}
  override_global.
  override_local.
  override_acls.
\end{verbatim}
With these lines the old global options (shared between all \ejabberd{} nodes in a
cluster), local options (which are specific for this particular \ejabberd{} node)
and ACLs will be removed before new ones are added.

\subsection{Host Names}
\label{hostnames}
\ind{options!hosts}\ind{host names}

The option \option{hosts} defines a list containing one or more domains that
\ejabberd{} will serve.

Examples:
\begin{itemize}
\item Serving one domain:
  \begin{verbatim}
  {hosts, ["example.org"]}.
\end{verbatim}
\item Serving one domain, and backwards compatible with older \ejabberd{}
  versions:
  \begin{verbatim}
  {host, "example.org"}.
\end{verbatim}
\item Serving two domains:
\begin{verbatim}
  {hosts, ["example.net", "example.com"]}.
\end{verbatim}
\end{itemize}

\subsection{Virtual Hosting}
\label{virtualhost}
\ind{virtual hosting}\ind{virtual hosts}\ind{virtual domains}

Options can be defined separately for every virtual host using the
\term{host\_config} option.\ind{options!host\_config} It has the following
syntax:
\begin{verbatim}
  {host_config, <hostname>, [<option>, <option>, ...]}.
\end{verbatim}

Examples:
\begin{itemize}
\item Domain \jid{example.net} is using the internal authentication method while
  domain \jid{example.com} is using the \ind{LDAP}LDAP server running on the
  domain \jid{localhost} to perform authentication:
\begin{verbatim}
{host_config, "example.net", [{auth_method, internal}]}.

{host_config, "example.com", [{auth_method, ldap},
                              {ldap_servers, ["localhost"]},
                              {ldap_uids, [{"uid"}]},
                              {ldap_rootdn, "dc=localdomain"},
                              {ldap_rootdn, "dc=example,dc=com"},
                              {ldap_password, ""}]}.
\end{verbatim}
\item Domain \jid{example.net} is using \ind{ODBC}ODBC to perform authentication
  while domain \jid{example.com} is using the LDAP servers running on the domains
  \jid{localhost} and \jid{otherhost}:
\begin{verbatim}
{host_config, "example.net", [{auth_method, odbc},
                              {odbc_server, "DSN=ejabberd;UID=ejabberd;PWD=ejabberd"}]}.

{host_config, "example.com", [{auth_method, ldap},
                              {ldap_servers, ["localhost", "otherhost"]},
                              {ldap_uids, [{"uid"}]},
                              {ldap_rootdn, "dc=localdomain"},
                              {ldap_rootdn, "dc=example,dc=com"},
                              {ldap_password, ""}]}.
\end{verbatim}
\end{itemize}
 
To define specific ejabberd modules in a virtual host,
you can define the global \term{modules} option with the common modules,
and later add specific modules to certain virtual hosts.
To accomplish that, instead of defining each option in \term{host\_config} with the syntax
\begin{verbatim}
  {<option-name>, <option-value>}
\end{verbatim}
use this syntax:
\begin{verbatim}
  {{add, <option-name>}, <option-value>}
\end{verbatim}

In this example three virtual hosts have some similar modules, but there are also
other different modules for some specific virtual hosts:
\begin{verbatim}
% This ejabberd server has three vhosts:
{hosts, ["one.example.org", "two.example.org", "three.example.org"]}.

% Configuration of modules that are common to all vhosts
{modules,
 [
  {mod_roster,     []},
  {mod_configure,  []},
  {mod_disco,      []},
  {mod_private,    []},
  {mod_time,       []},
  {mod_last,       []},
  {mod_version,    []}
 ]}.

% Add some modules to vhost one:
{host_config, "one.example.org", [{{add, modules}, [
  {mod_echo,       [{host, "echo-service.one.example.org"}]}
  {mod_http_bind,  []},
  {mod_logxml,     []}
]}]}.

% Add a module just to vhost two:
{host_config, "two.example.org", [{{add, modules}, [
  {mod_echo,       [{host, "mirror.two.example.org"}]}
]}]}.
\end{verbatim}

\subsection{Listening Ports}
\label{listened}
\ind{options!listen}

The option \option{listen} defines for which addresses and ports \ejabberd{}
will listen and what services will be run on them. Each element of the list is a
tuple with the following elements:
\begin{itemize}
\item Port number.
\item Module that serves this port.
\item Options to this module.
\end{itemize}

\ind{modules!ejabberd\_c2s}\ind{modules!ejabberd\_s2s\_in}\ind{modules!ejabberd\_service}\ind{modules!ejabberd\_http}\ind{protocols!XEP-0114: Jabber Component Protocol}
The available modules, their purpose and the options allowed by each one are:
\begin{table}[H]
  \centering
  \def\arraystretch{1.4}
  \begin{tabular}{|l|l|p{87mm}|}
  \hline \texttt{ejabberd\_c2s}& Description& Handles c2s connections.\\
    \cline{2-3} & Options& \texttt{access}, \texttt{certfile}, \texttt{inet6},
    \texttt{ip}, \texttt{max\_stanza\_size}, \texttt{shaper},
    \texttt{starttls}, \texttt{starttls\_required}, \texttt{tls},
    \texttt{zlib}\\
  \hline \texttt{ejabberd\_s2s\_in}& Description& Handles incoming s2s
  connections.\\
    \cline{2-3} & Options& \texttt{inet6}, \texttt{ip},
    \texttt{max\_stanza\_size}\\
  \hline \texttt{ejabberd\_service}& Description& Interacts with 
    \footahref{http://www.ejabberd.im/tutorials-transports}{external components} 
    (as defined in the Jabber Component Protocol (\xepref{0114}).\\
    \cline{2-3} & Options& \texttt{access}, \texttt{hosts}, \texttt{inet6},
    \texttt{ip}, \texttt{shaper}\\
  \hline \texttt{ejabberd\_http}& Description& Handles incoming HTTP
  connections.\\
    \cline{2-3} & Options& \texttt{certfile}, \texttt{http\_bind}, \texttt{http\_poll},
    \texttt{inet6}, \texttt{ip}, \texttt{request\_handlers}, \texttt{tls}, \texttt{web\_admin}\\
  \hline
  \end{tabular}
\end{table}

This is a detailed description of each option allowed by the listening modules:
\begin{description}
  \titem{\{access, <access rule>\}} \ind{options!access}This option defines
    access to the port. The default value is \term{all}.
  \titem{\{certfile, Path\}} Full path to a file containing the default SSL certificate.
    To define a certificate file specific for a given domain, use the global option \term{domain\_certfile}.
  \titem{component\_check\_from} \ind{options!service\_check\_from}
    This option can be used with \term{ejabberd\_service} only. It is
    used to disable control on the from field on packets send by an
    external components. The option can be either \term{true} or
    \term{false}. The default value is \term{true} which conforms to \xepref{0114}.
  \titem{\{hosts, [Hostnames], [HostOptions]\}} \ind{options!hosts}This option
    defines one or more hostnames of connected services and enables you to
    specify additional options including \poption{\{password, Secret\}}.
  \titem{http\_bind} \ind{options!http\_bind}\ind{protocols!XEP-0206: HTTP Binding}\ind{JWChat}\ind{web-based Jabber client}
    This option enables HTTP Binding (\xepref{0124} and \xepref{0206}) support. HTTP Bind
    enables access via HTTP requests to \ejabberd{} from behind firewalls which
    do not allow outgoing sockets on port 5222.

    Remember that you must also install and enable the module mod\_http\_bind.

    If HTTP Bind is enabled, it will be available at
    \verb|http://server:port/http-bind/|. Be aware that support for HTTP Bind
    is also needed in the \Jabber{} client. Remark also that HTTP Bind can be
    interesting to host a web-based \Jabber{} client such as
    \footahref{http://jwchat.sourceforge.net/}{JWChat} (there is a tutorial to
    \footahref{http://www.ejabberd.im/jwchat}{install JWChat} with
    instructions for \ejabberd{}).
  \titem{http\_poll} \ind{options!http\_poll}\ind{protocols!XEP-0025: HTTP Polling}\ind{JWChat}\ind{web-based Jabber client}
    This option enables HTTP Polling (\xepref{0025}) support. HTTP Polling
    enables access via HTTP requests to \ejabberd{} from behind firewalls which
    do not allow outgoing sockets on port 5222.

    If HTTP Polling is enabled, it will be available at
    \verb|http://server:port/http-poll/|. Be aware that support for HTTP Polling
    is also needed in the \Jabber{} client. Remark also that HTTP Polling can be
    interesting to host a web-based \Jabber{} client such as
    \footahref{http://jwchat.sourceforge.net/}{JWChat} (there is a tutorial to
    \footahref{http://www.ejabberd.im/jwchat}{install JWChat} with
    instructions for \ejabberd{}).
  \titem{inet6} \ind{options!inet6}\ind{IPv6}Set up the socket for IPv6.
  \titem{\{ip, IPAddress\}} \ind{options!ip}This option specifies which network
    interface to listen for. For example \verb|{ip, {192, 168, 1, 1}}|.
    \titem{\{max\_stanza\_size, Size\}}
    \ind{options!max\_stanza\_size}This option specifies an
    approximate maximum size in bytes of XML stanzas.  Approximate,
    because it is calculated with the precision of one block of readed
    data. For example \verb|{max_stanza_size, 65536}|.  The default
    value is \term{infinity}. Recommended values are 65536 for c2s
    connections and 131072 for s2s connections. s2s max stanza size
    must always much higher than c2s limit. Change this value with
    extreme care as it can cause unwanted disconnect if set too low.
  \titem{\{request\_handlers, [\{Path, Module\}]\}} To define one or several handlers that will serve HTTP requests.
    The Path is a list of strings; so the URIs that start with that Path will be served by Module.
    For example, if you want \term{mod\_foo} to serve the URIs that start with \term{/a/b/},
    and you also want \term{mod\_http\_bind} to serve the URIs \term{/http-bind/},
    use this option: \term{\{request\_handlers, [\{["a", "b"], mod\_foo\}, \{["http-bind"], mod\_http\_bind\}]\}}
  \titem{\{shaper, <access rule>\}} \ind{options!shaper}This option defines a
    shaper for the port (see section~\ref{shapers}). The default value
    is \term{none}.
  \titem{starttls} \ind{options!starttls}\ind{STARTTLS}This option
    specifies that STARTTLS encryption is available on connections to the port.
    You should also set the \option{certfile} option.
    You can define a certificate file for a specific domain using the global option \option{domain\_certfile}.
  \titem{starttls\_required} \ind{options!starttls\_required}This option
    specifies that STARTTLS encryption is required on connections to the port.
    No unencrypted connections will be allowed. 
    You should also set the \option{certfile} option.
    You can define a certificate file for a specific domain using the global option \option{domain\_certfile}.
  \titem{tls} \ind{options!tls}\ind{TLS}This option specifies that traffic on
    the port will be encrypted using SSL immediately after connecting. You
    should also set the \option{certfile} option.
  \titem{web\_admin} \ind{options!web\_admin}\ind{web admin}This option
    enables the Web Admin for \ejabberd{} administration which is available
    at \verb|http://server:port/admin/|. Login and password are the username and
    password of one of the registered users who are granted access by the
    `configure' access rule.
  \titem{zlib} \ind{options!zlib}\ind{protocols!XEP-0138: Stream Compression}\ind{Zlib}This
    option specifies that Zlib stream compression (as defined in \xepref{0138})
    is available on connections to the port. Client connections cannot use
    stream compression and stream encryption simultaneously. Hence, if you
    specify both \option{tls} (or \option{ssl}) and \option{zlib}, the latter
    option will not affect connections (there will be no stream compression).
\end{description}

There are some additional global options:
\begin{description}
  \titem{\{s2s\_use\_starttls, true|false\}}
  \ind{options!s2s\_use\_starttls}\ind{STARTTLS}This option defines whether to
  use STARTTLS for s2s connections.
  \titem{\{s2s\_certfile, Path\}} \ind{options!s2s\_certificate}Full path to a
  file containing a SSL certificate.
  \titem{\{domain\_certfile, Domain, Path\}} \ind{options!domain\_certfile}
  Full path to the file containing the SSL certificate for a specific domain.
\end{description}

For example, the following simple configuration defines:
\begin{itemize}
\item There are three domains. The default certificate file is \term{server.pem}.
However, the c2s and s2s connections to the domain \term{example.com} use the file \term{example\_com.pem}.
\item Port 5222 listens for c2s connections with STARTTLS, 
  and also allows plain connections for old clients.
\item Port 5223 listens for c2s connections with the old SSL.
\item Port 5269 listens for s2s connections with STARTTLS.
\item Port 5280 listens for HTTP requests, and serves the HTTP Poll service.
\item Port 5281 listens for HTTP requests, and serves the Web Admin using HTTPS as explained in
  section~\ref{webadmin}.
\end{itemize}
\begin{verbatim}
{hosts, ["example.com", "example.org", "example.net"]}.
{listen,
 [
  {5222, ejabberd_c2s, [
                        {access, c2s}, 
                        {shaper, c2s_shaper},
                        starttls, {certfile, "/etc/ejabberd/server.pem"},
                        {max_stanza_size, 65536}
                       ]},
  {5223, ejabberd_c2s, [
                        {access, c2s},
                        {shaper, c2s_shaper},
                        tls, {certfile, "/etc/ejabberd/server.pem"},
                        {max_stanza_size, 65536}
                       ]},
  {5269, ejabberd_s2s_in, [
                           {shaper, s2s_shaper},
                           {max_stanza_size, 131072}
                          ]},
  {5280, ejabberd_http, [
                         http_poll
                        ]},
  {5281, ejabberd_http, [
                         web_admin,
                         tls, {certfile, "/etc/ejabberd/server.pem"},
                        ]}
 ]
}.
{s2s_use_starttls, true}.
{s2s_certfile, "/etc/ejabberd/server.pem"}.
{domain_certfile, "example.com", "/etc/ejabberd/example_com.pem"}.
\end{verbatim}

In this example, the following configuration defines that:
\begin{itemize}
\item c2s connections are listened for on port 5222 and 5223 (SSL) and denied
  for the user called `\term{bad}'.
\item s2s connections are listened for on port 5269 with STARTTLS for secured
  traffic enabled.
\item Port 5280 is serving the Web Admin and the HTTP Polling service. Note
  that it is also possible to serve them on different ports. The second
  example in section~\ref{webinterface} shows how exactly this can be done.
\item All users except for the administrators have a traffic of limit 
  1,000\,Bytes/second
\item \ind{transports!AIM}The
  \footahref{http://www.ejabberd.im/pyaimt}{AIM transport}
  \jid{aim.example.org} is connected to port 5233 with password
  `\term{aimsecret}'.
\item \ind{transports!ICQ}The ICQ transport JIT (\jid{icq.example.org} and
  \jid{sms.example.org}) is connected to port 5234 with password
  `\term{jitsecret}'.
\item \ind{transports!MSN}The
  \footahref{http://www.ejabberd.im/pymsnt}{MSN transport}
  \jid{msn.example.org} is connected to port 5235 with password
  `\term{msnsecret}'.
\item \ind{transports!Yahoo}The
  \footahref{http://www.ejabberd.im/yahoo-transport-2}{Yahoo! transport}
  \jid{yahoo.example.org} is connected to port 5236 with password
  `\term{yahoosecret}'.
\item \ind{transports!Gadu-Gadu}The \footahref{http://www.ejabberd.im/jabber-gg-transport}{Gadu-Gadu transport} \jid{gg.example.org} is
  connected to port 5237 with password `\term{ggsecret}'.
\item \ind{transports!email notifier}The
  \footahref{http://www.ejabberd.im/jmc}{Jabber Mail Component}
  \jid{jmc.example.org} is connected to port 5238 with password
  `\term{jmcsecret}'.
\item The service custom has enabled the special option to avoiding checking the \term{from} attribute in the packets send by this component. The component can send packets in behalf of any users from the server, or even on behalf of any server.
\end{itemize}
\begin{verbatim}
  {acl, blocked, {user, "bad"}}.
  {access, c2s, [{deny, blocked},
                 {allow, all}]}.
  {shaper, normal, {maxrate, 1000}}.
  {access, c2s_shaper, [{none, admin},
                        {normal, all}]}.
  {listen,
   [{5222, ejabberd_c2s,     [{access, c2s}, {shaper, c2s_shaper}]},
    {5223, ejabberd_c2s,     [{access, c2s},
                              ssl, {certfile, "/path/to/ssl.pem"}]},
    {5269, ejabberd_s2s_in,  []},
    {5280, ejabberd_http,    [http_poll, web_admin]},
    {5233, ejabberd_service, [{host, "aim.example.org",
                               [{password, "aimsecret"}]}]},
    {5234, ejabberd_service, [{hosts, ["icq.example.org", "sms.example.org"],
                               [{password, "jitsecret"}]}]},
    {5235, ejabberd_service, [{host, "msn.example.org",
                               [{password, "msnsecret"}]}]},
    {5236, ejabberd_service, [{host, "yahoo.example.org",
                               [{password, "yahoosecret"}]}]},
    {5237, ejabberd_service, [{host, "gg.example.org",
                               [{password, "ggsecret"}]}]},
    {5238, ejabberd_service, [{host, "jmc.example.org",
                               [{password, "jmcsecret"}]}]},
    {5239, ejabberd_service, [{host, "custom.example.org",
                               [{password, "customsecret"}]},
                              {service_check_from, false}]}
   ]
  }.
  {s2s_use_starttls, true}.
  {s2s_certfile, "/path/to/ssl.pem"}.
\end{verbatim}
Note, that for \ind{jabberd 1.4}jabberd 1.4- or \ind{WPJabber}WPJabber-based
services you have to make the transports log and do \ind{XDB}XDB by themselves:
\begin{verbatim}
  <!--
     You have to add elogger and rlogger entries here when using ejabberd.
     In this case the transport will do the logging.
  -->

  <log id='logger'>
    <host/>
    <logtype/>
    <format>%d: [%t] (%h): %s</format>
    <file>/var/log/jabber/service.log</file>
  </log>

  <!--
     Some Jabber server implementations do not provide
     XDB services (for example, jabberd2 and ejabberd).
     xdb_file.so is loaded in to handle all XDB requests.
  -->

  <xdb id="xdb">
    <host/>
    <load>
      <!-- this is a lib of wpjabber or jabberd -->
      <xdb_file>/usr/lib/jabber/xdb_file.so</xdb_file>
      </load>
    <xdb_file xmlns="jabber:config:xdb_file">
      <spool><jabberd:cmdline flag='s'>/var/spool/jabber</jabberd:cmdline></spool>
    </xdb_file>
  </xdb>
\end{verbatim}

\subsection{Authentication}
\label{auth}
\ind{authentication}\ind{options!auth\_method}

The option \option{auth\_method} defines the authentication method that is used
for user authentication:
\begin{verbatim}
  {auth_method, [<method>]}.
\end{verbatim}

The following authentication methods are supported by \ejabberd{}:
\begin{itemize}
\item internal (default) --- See section~\ref{internalauth}.
\item external --- There are \footahref{http://www.ejabberd.im/extauth}{some
 example authentication scripts}.
\item ldap --- See section~\ref{ldap}.
\item odbc --- See section~\ref{mysql}, \ref{pgsql},
  \ref{mssql} and \ref{odbc}.
\item anonymous --- See section~\ref{saslanonymous}.
\item pam --- See section~\ref{pam}.
\end{itemize}

\subsubsection{Internal}
\label{internalauth}
\ind{internal authentication}\ind{Mnesia}

\ejabberd{} uses its internal Mnesia database as the default authentication method.

\begin{itemize}
\item \term{auth\_method}: The value \term{internal} will enable the internal
  authentication method.
\end{itemize}

Examples:
\begin{itemize}
\item To use internal authentication on \jid{example.org} and LDAP
  authentication on \jid{example.net}:
  \begin{verbatim}
{host_config, "example.org", [{auth_method, [internal]}]}.
{host_config, "example.net", [{auth_method, [ldap]}]}.
\end{verbatim}
\item To use internal authentication on all virtual hosts:
  \begin{verbatim}
{auth_method, internal}.
\end{verbatim}
\end{itemize}

\subsubsection{SASL Anonymous and Anonymous Login}
\label{saslanonymous}
\ind{sasl anonymous}\ind{anonymous login}

%TODO: introduction; tell what people can do with this
The anonymous authentication method can be configured with the following
options. Remember that you can use the \term{host\_config} option to set virtual
host specific options (see section~\ref{virtualhost}). Note that there also
is a detailed tutorial regarding \footahref{http://support.process-one.net/doc/display/MESSENGER/Anonymous+users+support}{SASL
Anonymous and anonymous login configuration}.

\begin{itemize}
\item \term{auth\_method}: The value \term{anonymous} will enable the anonymous
  authentication method.
\item \term{allow\_multiple\_connections}: This value for this option can be
  either \term{true} or \term{false} and is only used when the anonymous mode is
  enabled. Setting it to \term{true} means that the same username can be taken
  multiple times in anonymous login mode if different resource are used to
  connect. This option is only useful in very special occasions. The default
  value is \term{false}.
\item \term{anonymous\_protocol}: This option can take three values:
  \term{sasl\_anon}, \term{login\_anon} or \term{both}. \term{sasl\_anon} means
  that the SASL Anonymous method will be used. \term{login\_anon} means that the
  anonymous login method will be used. \term{both} means that SASL Anonymous and
  login anonymous are both enabled.
\end{itemize}

Those options are defined for each virtual host with the \term{host\_config}
parameter (see section~\ref{virtualhost}).

Examples:
\begin{itemize}
\item To enable anonymous login on all virtual hosts:
  \begin{verbatim}
{auth_method, [anonymous]}.
{anonymous_protocol, login_anon}.
  \end{verbatim}
\item Similar as previous example, but limited to \jid{public.example.org}:
  \begin{verbatim}
{host_config, "public.example.org", [{auth_method, [anonymous]},
                                     {anonymous_protocol, login_anon}]}.
\end{verbatim}
\item To enable anonymous login and internal authentication on a virtual host:
  \begin{verbatim}
{host_config, "public.example.org", [{auth_method, [internal,anonymous]},
                                     {anonymous_protocol, login_anon}]}.
\end{verbatim}
\item To enable SASL Anonymous on a virtual host:
  \begin{verbatim}
{host_config, "public.example.org", [{auth_method, [anonymous]},
                                     {anonymous_protocol, sasl_anon}]}.
\end{verbatim}
\item To enable SASL Anonymous and anonymous login on a virtual host:
  \begin{verbatim}
{host_config, "public.example.org", [{auth_method, [anonymous]},
                                     {anonymous_protocol, both}]}.
\end{verbatim}
\item To enable SASL Anonymous, anonymous login, and internal authentication on
a virtual host:
  \begin{verbatim}
{host_config, "public.example.org", [{auth_method, [internal,anonymous]},
                                     {anonymous_protocol, both}]}.
\end{verbatim}
\end{itemize}

\subsubsection{PAM Authentication}
\label{pam}
\ind{PAM authentication}\ind{Pluggable Authentication Modules}

\ejabberd{} supports authentication via Pluggable Authentication Modules (PAM).
PAM is currently supported in AIX, FreeBSD, HP-UX, Linux, Mac OS X, NetBSD and Solaris.
PAM authentication is disabled by default, so you have to configure and compile
\ejabberd{} with PAM support enabled:
\begin{verbatim}
./configure --enable-pam && make install
\end{verbatim}

Options:
\begin{description}
\titem{pam\_service}\ind{options!pam\_service}This option defines the PAM service name.
Default is \term{"ejabberd"}. Refer to the PAM documentation of your operation system
for more information.
\end{description}

Example:
\begin{verbatim}
  {auth_method, [pam]}.
  {pam_service, "ejabberd"}.
\end{verbatim}

Though it is quite easy to set up PAM support in \ejabberd{}, PAM itself introduces some
security issues:

\begin{itemize}
\item To perform PAM authentication \ejabberd{} uses external C-program called
\term{epam}. By default, it is located in \verb|/var/lib/ejabberd/priv/lib/|
directory. You have to set it root on execution in the case when your PAM module
requires root privileges (\term{pam\_unix.so} for example). Also you have to grant access
for \ejabberd{} to this file and remove all other permissions from it:
\begin{verbatim}
# chown root:ejabberd /var/lib/ejabberd/priv/lib/epam
# chmod 4750 /var/lib/ejabberd/priv/lib/epam
\end{verbatim}
\item Make sure you have the latest version of PAM installed on your system.
Some old versions of PAM modules cause memory leaks. If you are not able to use the latest
version, you can \term{kill(1)} \term{epam} process periodically to reduce its memory
consumption: \ejabberd{} will restart this process immediately.
\item \term{epam} program tries to turn off delays on authentication failures.
However, some PAM modules ignore this behavior and rely on their own configuration options.
The example configuration file \term{ejabberd.pam} shows how to turn off delays in
\term{pam\_unix.so} module. It is not a ready to use configuration file: you must use it
as a hint when building your own PAM configuration instead. Note that if you want to disable
delays on authentication failures in the PAM configuration file, you have to restrict access
to this file, so a malicious user can't use your configuration to perform brute-force
attacks.
\item You may want to allow login access only for certain users. \term{pam\_listfile.so}
module provides such functionality.
\end{itemize}

\subsection{Access Rules}
\label{accessrules}
\ind{access rules}\ind{ACL}\ind{Access Control List}

\subsubsection{ACL Definition}
\label{ACLDefinition}
\ind{ACL}\ind{options!acl}\ind{ACL}\ind{Access Control List}

Access control in \ejabberd{} is performed via Access Control Lists (ACLs). The
declarations of ACLs in the configuration file have the following syntax:
\begin{verbatim}
  {acl, <aclname>, {<acltype>, ...}}.
\end{verbatim}
\term{<acltype>} can be one of the following:
\begin{description}
\titem{all} Matches all JIDs. Example:
\begin{verbatim}
{acl, all, all}.
\end{verbatim}
\titem{\{user, <username>\}} Matches the user with the name
  \term{<username>} at the first virtual host. Example:
\begin{verbatim}
{acl, admin, {user, "yozhik"}}.
\end{verbatim}
\titem{\{user, <username>, <server>\}} Matches the user with the JID
  \term{<username>@<server>} and any resource. Example:
\begin{verbatim}
{acl, admin, {user, "yozhik", "example.org"}}.
\end{verbatim}
\titem{\{server, <server>\}} Matches any JID from server
  \term{<server>}. Example:
\begin{verbatim}
{acl, exampleorg, {server, "example.org"}}.
\end{verbatim}
\titem{\{user\_regexp, <regexp>\}} Matches any local user with a name that
  matches \term{<regexp>} on local virtual hosts. Example:
\begin{verbatim}
{acl, tests, {user_regexp, "^test[0-9]*$"}}.
\end{verbatim}
%$
\titem{\{user\_regexp, <regexp>, <server>\}} Matches any user with a name
  that matches \term{<regexp>} at server \term{<server>}. Example:
\begin{verbatim}
{acl, tests, {user_regexp, "^test", "example.org"}}.
\end{verbatim}
\titem{\{server\_regexp, <regexp>\}} Matches any JID from the server that
  matches \term{<regexp>}. Example:
\begin{verbatim}
{acl, icq, {server_regexp, "^icq\\."}}.
\end{verbatim}
\titem{\{node\_regexp, <user\_regexp>, <server\_regexp>\}} Matches any user
  with a name that matches \term{<user\_regexp>} at any server that matches
  \term{<server\_regexp>}. Example:
\begin{verbatim}
{acl, yohzik, {node_regexp, "^yohzik$", "^example.(com|org)$"}}.
\end{verbatim}
\titem{\{user\_glob, <glob>\}}
\titem{\{user\_glob, <glob>, <server>\}}
\titem{\{server\_glob, <glob>\}}
\titem{\{node\_glob, <user\_glob>, <server\_glob>\}} This is the same as
  above. However, it uses shell glob patterns instead of regexp. These patterns
  can have the following special characters:
  \begin{description}
  \titem{*} matches any string including the null string.
  \titem{?} matches any single character.
  \titem{[...]} matches any of the enclosed characters. Character
    ranges are specified by a pair of characters separated by a \term{`-'}.
    If the first character after \term{`['} is a \term{`!'}, any
    character not enclosed is matched.
  \end{description}
\end{description}

The following ACLs are pre-defined:
\begin{description}
\titem{all} Matches any JID.
\titem{none} Matches no JID.
\end{description}

\subsubsection{Access Rights}
\label{AccessRights}
\ind{access}\ind{ACL}\ind{options!acl}\ind{ACL}\ind{Access Control List}

An entry allowing or denying access to different services looks similar to
this:
\begin{verbatim}
  {access, <accessname>, [{allow, <aclname>},
                          {deny, <aclname>},
                          ...
                         ]}.
\end{verbatim}
When a JID is checked to have access to \term{<accessname>}, the server
sequentially checks if that JID matches any of the ACLs that are named in the
second elements of the tuples in the list. If it matches, the first element of
the first matched tuple is returned, otherwise the value `\term{deny}' is
returned.

Example:
\begin{verbatim}
  {access, configure, [{allow, admin}]}.
  {access, something, [{deny, badmans},
                       {allow, all}]}.
\end{verbatim}

The following access rules are pre-defined:
\begin{description}
\titem{all} Always returns the value `\term{allow}'.
\titem{none} Always returns the value `\term{deny}'.
\end{description}

\subsubsection{Limiting Opened Sessions with ACL}
\label{configmaxsessions}
\ind{options!max\_user\_sessions}

The special access \term{max\_user\_sessions} specifies the maximum
number of sessions (authenticated connections) per user. If a user
tries to open more sessions by using different resources, the first
opened session will be disconnected. The error \term{session replaced}
will be sent to the disconnected session. The value for this option
can be either a number, or \term{infinity}.  The default value is
\term{infinity}.

The syntax is:
\begin{verbatim}
  {access, max_user_sessions, [{<maxnumber>, <aclname>},
                               ...
                              ]}.
\end{verbatim}

Examples:
\begin{itemize}
\item To limit the number of sessions per user to 10 for all users:
\begin{verbatim}
  {access, max_user_sessions, [{10, all}]}.
\end{verbatim}
\end{itemize}

\subsection{Shapers}
\label{shapers}
\ind{options!shaper}\ind{options!maxrate}\ind{shapers}\ind{maxrate}\ind{traffic speed}

Shapers enable you to limit connection traffic. The syntax of
shapers is like this:
\begin{verbatim}
  {shaper, <shapername>, <kind>}.
\end{verbatim}
Currently only one kind of shaper called \term{maxrate} is available. It has the
following syntax:
\begin{verbatim}
  {maxrate, <rate>}
\end{verbatim}
where \term{<rate>} stands for the maximum allowed incoming rate in bytes per
second.

Examples:
\begin{itemize}
\item To define a shaper named `\term{normal}' with traffic speed limited to
1,000\,bytes/second:
\begin{verbatim}
  {shaper, normal, {maxrate, 1000}}.
\end{verbatim}
\item To define a shaper named `\term{fast}' with traffic speed limited to
50,000\,bytes/second:
\begin{verbatim}
  {shaper, fast, {maxrate, 50000}}.
\end{verbatim}
\end{itemize}

\subsection{Default Language}
\label{language}
\ind{options!language}\ind{language}

The option \option{language} defines the default language of server strings that
can be seen by \Jabber{} clients. If a \Jabber{} client do not support
\option{xml:lang}, the specified language is used. The default value is
\term{en}. In order to take effect there must be a translation file
\term{<language>.msg} in \ejabberd{}'s \term{msgs} directory.

Examples:
\begin{itemize}
\item To set Russian as default language:
\begin{verbatim}
  {language, "ru"}.
\end{verbatim}
\item To set Spanish as default language:
\begin{verbatim}
  {language, "es"}.
\end{verbatim}
\end{itemize}

\section{Database and LDAP Configuration}
\label{database}
\ind{database}
%TODO: this whole section is not yet 100% optimized

\ejabberd{} uses its internal Mnesia database by default. However, it is
possible to use a relational database or an LDAP server to store persistent,
long-living data. \ejabberd{} is very flexible: you can configure different
authentication methods for different virtual hosts, you can configure different
authentication mechanisms for the same virtual host (fallback), you can set
different storage systems for modules, and so forth.

The following databases are supported by \ejabberd{}:
\begin{itemize}
\item \footahref{http://www.microsoft.com/sql/}{Microsoft SQL Server}
\item \footahref{http://www.erlang.org/doc/doc-5.5.1/lib/mnesia-4.3.2/doc/}{Mnesia}
\item \footahref{http://mysql.com/}{MySQL}
\item \footahref{http://en.wikipedia.org/wiki/Open\_Database\_Connectivity}{Any ODBC compatible database}
\item \footahref{http://www.postgresql.org/}{PostgreSQL}
\end{itemize}

The following LDAP servers are tested with \ejabberd{}:
\begin{itemize}
\item \footahref{http://www.microsoft.com/activedirectory/}{Active Directory}
  (see section~\ref{ad})
\item \footahref{http://www.openldap.org/}{OpenLDAP}
\item Normally any LDAP compatible server should work; inform us about your
  success with a not-listed server so that we can list it here.
\end{itemize}

\subsection{MySQL}
\label{mysql}
\ind{MySQL}\ind{MySQL!schema}

Although this section will describe \ejabberd{}'s configuration when you want to
use the native MySQL driver, it does not describe MySQL's installation and
database creation. Check the MySQL documentation and the tutorial \footahref{http://support.process-one.net/doc/display/MESSENGER/Using+ejabberd+with+MySQL+native+driver}{Using ejabberd with MySQL native driver} for information regarding these topics.
Note that the tutorial contains information about \ejabberd{}'s configuration
which is duplicate to this section.

Moreover, the file mysql.sql in the directory src/odbc might be interesting for
you. This file contains the \ejabberd{} schema for MySQL. At the end of the file
you can find information to update your database schema.

By default \ejabberd{} opens 10 connections to the database for each virtual host.
Use this option to modify the value:
\begin{verbatim}
{odbc_pool_size, 10}.
\end{verbatim}

You can configure an interval to make a dummy SQL request 
to keep alive the connections to the database. 
The default value is 'undefined', so no keepalive requests are made. 
Specify in seconds: for example 28800 means 8 hours.
\begin{verbatim}
{odbc_keepalive_interval, undefined}.
\end{verbatim}

\subsubsection{Driver Compilation}
\label{compilemysql}
\ind{MySQL!Driver Compilation}

You can skip this step if you installed \ejabberd{} using a binary installer or
if the binary packages of \ejabberd{} you are using include support for MySQL.

\begin{enumerate}
\item First, install the \footahref{http://support.process-one.net/doc/display/CONTRIBS/Yxa}{Erlang
  MySQL library}. Make sure the compiled files are in your Erlang path; you can
  put them for example in the same directory as your \ejabberd{} .beam files.
\item Then, configure and install \ejabberd{} with ODBC support enabled (this is
  also needed for native MySQL support!). This can be done, by using next
  commands:
  \begin{verbatim}
./configure --enable-odbc && make install
\end{verbatim}
\end{enumerate}

\subsubsection{Authentication}
\label{mysqlauth}
\ind{MySQL!authentication}

The option value name may be misleading, as the \term{auth\_method} name is used
for access to a relational database through ODBC, as well as through the native
MySQL interface. Anyway, the first configuration step is to define the odbc
\term{auth\_method}. For example:
\begin{verbatim}
{host_config, "public.example.org", [{auth_method, [odbc]}]}.
\end{verbatim}

The actual database access is defined in the option \term{odbc\_server}. Its
value is used to define if we want to use ODBC, or one of the two native
interface available, PostgreSQL or MySQL.

To use the native MySQL interface, you can pass a tuple of the following form as
parameter:
\begin{verbatim}
{mysql, "Server", "Database", "Username", "Password"}
\end{verbatim}

\term{mysql} is a keyword that should be kept as is. For example:
\begin{verbatim}
{odbc_server, {mysql, "localhost", "test", "root", "password"}}.
\end{verbatim}

Optionally, it is possible to define the MySQL port to use. This
option is only useful, in very rare cases, when you are not running
MySQL with the default port setting. The \term{mysql} parameter
can thus take the following form:
\begin{verbatim}
{mysql, "Server", Port, "Database", "Username", "Password"}
\end{verbatim}

The \term{Port} value should be an integer, without quotes. For example:
\begin{verbatim}
{odbc_server, {mysql, "localhost", Port, "test", "root", "password"}}.
\end{verbatim}


\subsubsection{Storage}
\label{mysqlstorage}
\ind{MySQL!storage}

MySQL also can be used to store information into from several \ejabberd{}
modules. See section~\ref{modoverview} to see which modules have a version
with the `\_odbc'. This suffix indicates that the module can be used with
relational databases like MySQL. To enable storage to your database, just make
sure that your database is running well (see previous sections), and replace the
suffix-less or ldap module variant with the odbc module variant. Keep in mind
that you cannot have several variants of the same module loaded!

\subsection{Microsoft SQL Server}
\label{mssql}
\ind{Microsoft SQL Server}\ind{Microsoft SQL Server!schema}

Although this section will describe \ejabberd{}'s configuration when you want to
use Microsoft SQL Server, it does not describe Microsoft SQL Server's
installation and database creation. Check the MySQL documentation and the
tutorial \footahref{http://support.process-one.net/doc/display/MESSENGER/Using+ejabberd+with+MySQL+native+driver}{Using ejabberd with MySQL native driver} for information regarding these topics.
Note that the tutorial contains information about \ejabberd{}'s configuration
which is duplicate to this section.

Moreover, the file mssql.sql in the directory src/odbc might be interesting for
you. This file contains the \ejabberd{} schema for Microsoft SQL Server. At the end
of the file you can find information to update your database schema.

By default \ejabberd{} opens 10 connections to the database for each virtual host.
Use this option to modify the value:
\begin{verbatim}
{odbc_pool_size, 10}.
\end{verbatim}

You can configure an interval to make a dummy SQL request 
to keep alive the connections to the database. 
The default value is 'undefined', so no keepalive requests are made. 
Specify in seconds: for example 28800 means 8 hours.
\begin{verbatim}
{odbc_keepalive_interval, undefined}.
\end{verbatim}

\subsubsection{Driver Compilation}
\label{compilemssql}
\ind{Microsoft SQL Server!Driver Compilation}

You can skip this step if you installed \ejabberd{} using a binary installer or
if the binary packages of \ejabberd{} you are using include support for ODBC.

If you want to use Microsoft SQL Server with ODBC, you need to configure,
compile and install \ejabberd{} with support for ODBC and Microsoft SQL Server
enabled. This can be done, by using next commands:
\begin{verbatim}
./configure --enable-odbc --enable-mssql && make install
\end{verbatim}

\subsubsection{Authentication}
\label{mssqlauth}
\ind{Microsoft SQL Server!authentication}

%TODO: not sure if this section is right!!!!!!

The configuration of Microsoft SQL Server is the same as the configuration of
ODBC compatible servers (see section~\ref{odbcauth}).

\subsubsection{Storage}
\label{mssqlstorage}
\ind{Microsoft SQL Server!storage}

Microsoft SQL Server also can be used to store information into from several
\ejabberd{} modules. See section~\ref{modoverview} to see which modules have
a version with the `\_odbc'. This suffix indicates that the module can be used
with relational databases like Microsoft SQL Server. To enable storage to your
database, just make sure that your database is running well (see previous
sections), and replace the suffix-less or ldap module variant with the odbc
module variant. Keep in mind that you cannot have several variants of the same
module loaded!

\subsection{PostgreSQL}
\label{pgsql}
\ind{PostgreSQL}\ind{PostgreSQL!schema}

Although this section will describe \ejabberd{}'s configuration when you want to
use the native PostgreSQL driver, it does not describe PostgreSQL's installation
and database creation. Check the PostgreSQL documentation and the tutorial \footahref{http://support.process-one.net/doc/display/MESSENGER/Using+ejabberd+with+MySQL+native+driver}{Using ejabberd with MySQL native driver} for information regarding these topics.
Note that the tutorial contains information about \ejabberd{}'s configuration
which is duplicate to this section.

Also the file pg.sql in the directory src/odbc might be interesting for you.
This file contains the \ejabberd{} schema for PostgreSQL. At the end of the file
you can find information to update your database schema.

By default \ejabberd{} opens 10 connections to the database for each virtual host.
Use this option to modify the value:
\begin{verbatim}
{odbc_pool_size, 10}.
\end{verbatim}

You can configure an interval to make a dummy SQL request 
to keep alive the connections to the database. 
The default value is 'undefined', so no keepalive requests are made. 
Specify in seconds: for example 28800 means 8 hours.
\begin{verbatim}
{odbc_keepalive_interval, undefined}.
\end{verbatim}

\subsubsection{Driver Compilation}
\label{compilepgsql}
\ind{PostgreSQL!Driver Compilation}

You can skip this step if you installed \ejabberd{} using a binary installer or
if the binary packages of \ejabberd{} you are using include support for
PostgreSQL.

\begin{enumerate}
\item First, install the Erlang pgsql library from
  \footahref{http://www.ejabberd.im/ejabberd-modules/}{ejabberd-modules SVN repository}. 
  Make sure the compiled
  files are in your Erlang path; you can put them for example in the same
  directory as your \ejabberd{} .beam files.
\item Then, configure, compile and install \ejabberd{} with ODBC support enabled
  (this is also needed for native PostgreSQL support!). This can be done, by
  using next commands:
  \begin{verbatim}
./configure --enable-odbc && make install
\end{verbatim}
\end{enumerate}

\subsubsection{Authentication}
\label{pgsqlauth}
\ind{PostgreSQL!authentication}

The option value name may be misleading, as the \term{auth\_method} name is used
for access to a relational database through ODBC, as well as through the native
PostgreSQL interface. Anyway, the first configuration step is to define the odbc
\term{auth\_method}. For example:
\begin{verbatim}
{host_config, "public.example.org", [{auth_method, [odbc]}]}.
\end{verbatim}

The actual database access is defined in the option \term{odbc\_server}. Its
value is used to define if we want to use ODBC, or one of the two native
interface available, PostgreSQL or MySQL.

To use the native PostgreSQL interface, you can pass a tuple of the following
form as parameter:
\begin{verbatim}
{pgsql, "Server", "Database", "Username", "Password"}
\end{verbatim}

\term{pgsql} is a keyword that should be kept as is. For example:
\begin{verbatim}
{odbc_server, {pgsql, "localhost", "database", "ejabberd", "password"}}.
\end{verbatim}

Optionally, it is possible to define the PostgreSQL port to use. This
option is only useful, in very rare cases, when you are not running
PostgreSQL with the default port setting. The \term{pgsql} parameter
can thus take the following form:
\begin{verbatim}
{pgsql, "Server", Port, "Database", "Username", "Password"}
\end{verbatim}

The \term{Port} value should be an integer, without quotes. For example:
\begin{verbatim}
{odbc_server, {pgsql, "localhost", 5432, "database", "ejabberd", "password"}}.
\end{verbatim}

\subsubsection{Storage}
\label{pgsqlstorage}
\ind{PostgreSQL!storage}

PostgreSQL also can be used to store information into from several \ejabberd{}
modules. See section~\ref{modoverview} to see which modules have a version
with the `\_odbc'. This suffix indicates that the module can be used with
relational databases like PostgreSQL. To enable storage to your database, just
make sure that your database is running well (see previous sections), and
replace the suffix-less or ldap module variant with the odbc module variant.
Keep in mind that you cannot have several variants of the same module loaded!

\subsection{ODBC Compatible}
\label{odbc}
\ind{databases!ODBC}

Although this section will describe \ejabberd{}'s configuration when you want to
use the ODBC driver, it does not describe the installation and database creation
of your database. Check the documentation of your database. The tutorial \footahref{http://support.process-one.net/doc/display/MESSENGER/Using+ejabberd+with+MySQL+native+driver}{Using ejabberd with MySQL native driver} also can help you. Note that the tutorial
contains information about \ejabberd{}'s configuration which is duplicate to
this section.

By default \ejabberd{} opens 10 connections to the database for each virtual host.
Use this option to modify the value:
\begin{verbatim}
{odbc_pool_size, 10}.
\end{verbatim}

You can configure an interval to make a dummy SQL request 
to keep alive the connections to the database. 
The default value is 'undefined', so no keepalive requests are made. 
Specify in seconds: for example 28800 means 8 hours.
\begin{verbatim}
{odbc_keepalive_interval, undefined}.
\end{verbatim}

\subsubsection{Driver Compilation}
\label{compileodbc}

You can skip this step if you installed \ejabberd{} using a binary installer or
if the binary packages of \ejabberd{} you are using include support for
ODBC.

\begin{enumerate}
\item First, install the \footahref{http://support.process-one.net/doc/display/CONTRIBS/Yxa}{Erlang
  MySQL library}. Make sure the compiled files are in your Erlang path; you can
  put them for example in the same directory as your \ejabberd{} .beam files.
\item Then, configure, compile and install \ejabberd{} with ODBC support
  enabled. This can be done, by using next commands:
  \begin{verbatim}
./configure --enable-odbc && make install
\end{verbatim}
\end{enumerate}

\subsubsection{Authentication}
\label{odbcauth}
\ind{ODBC!authentication}

The first configuration step is to define the odbc \term{auth\_method}. For
example:
\begin{verbatim}
{host_config, "public.example.org", [{auth_method, [odbc]}]}.
\end{verbatim}

The actual database access is defined in the option \term{odbc\_server}. Its
value is used to defined if we want to use ODBC, or one of the two native
interface available, PostgreSQL or MySQL.

To use a relational database through ODBC, you can pass the ODBC connection
string as \term{odbc\_server} parameter. For example:
\begin{verbatim}
{odbc_server, "DSN=database;UID=ejabberd;PWD=password"}.
\end{verbatim}

\subsubsection{Storage}
\label{odbcstorage}
\ind{ODBC!storage}

An ODBC compatible database also can be used to store information into from
several \ejabberd{} modules. See section~\ref{modoverview} to see which
modules have a version with the `\_odbc'. This suffix indicates that the module
can be used with ODBC compatible relational databases. To enable storage to your
database, just make sure that your database is running well (see previous
sections), and replace the suffix-less or ldap module variant with the odbc
module variant. Keep in mind that you cannot have several variants of the same
module loaded!

\subsection{LDAP}
\label{ldap}
\ind{databases!LDAP}

\ejabberd{} has built-in LDAP support. You can authenticate users against LDAP
server and use LDAP directory as vCard storage. Shared rosters are not supported
yet.

\subsubsection{Connection}
\label{ldapconnection}

Parameters:
\begin{description}
\titem{ldap\_servers} \ind{options!ldap\_server}List of IP addresses or DNS names of your
LDAP servers. This option is required.
\titem{ldap\_port} \ind{options!ldap\_port}Port to connect to your LDAP server.
  The initial default value is~389, so it is used when nothing is set into the 
configuration file. 
If you configure a value, it is stored in \ejabberd{}'s database. 
Then, if you remove that value from the configuration file, 
the value previously stored in the database will be used instead of the default 389.
\titem{ldap\_rootdn} \ind{options!ldap\_rootdn}Bind DN. The default value
  is~\term{""} which means `anonymous connection'.
\titem{ldap\_password} \ind{options!ldap\_password}Bind password. The default
  value is \term{""}.
\end{description}

Example:
\begin{verbatim}
  {auth_method, ldap}.
  {ldap_servers, ["ldap.example.org"]}.
  {ldap_port, 389}.
  {ldap_rootdn, "cn=Manager,dc=domain,dc=org"}.
  {ldap_password, "secret"}.
\end{verbatim}

Note that current LDAP implementation does not support SSL secured communication
and SASL authentication.

\subsubsection{Authentication}
\label{ldapauth}

You can authenticate users against an LDAP directory. Available options are:

\begin{description}
\titem{ldap\_base}\ind{options!ldap\_base}LDAP base directory which stores
  users accounts. This option is required.
  \titem{ldap\_uids}\ind{options!ldap\_uids}LDAP attribute which holds a list
  of attributes to use as alternatives for getting the JID. The value is of
  the form: \term{[\{ldap\_uidattr\}]} or \term{[\{ldap\_uidattr,
  ldap\_uidattr\_format\}]}. You can use as many comma separated tuples
  \term{\{ldap\_uidattr, ldap\_uidattr\_format\}} that is needed. The default
  value is \term{[\{"uid", "\%u"\}]}. The defaut \term{ldap\_uidattr\_format}
  is \term{"\%u"}. The values for \term{ldap\_uidattr} and
  \term{ldap\_uidattr\_format} are described as follow:
  \begin{description}
    \titem{ldap\_uidattr}\ind{options!ldap\_uidattr}LDAP attribute which holds
    the user's part of a JID. The default value is \term{"uid"}.
    \titem{ldap\_uidattr\_format}\ind{options!ldap\_uidattr\_format}Format of
    the \term{ldap\_uidattr} variable. The format \emph{must} contain one and
    only one pattern variable \term{"\%u"} which will be replaced by the
    user's part of a JID. For example, \term{"\%u@example.org"}. The default
    value is \term{"\%u"}.
  \end{description}
  \titem{ldap\_filter}\ind{options!ldap\_filter}\ind{protocols!RFC 2254: The
  String Representation of LDAP Search Filters}
  \footahref{http://www.faqs.org/rfcs/rfc2254.html}{RFC 2254} LDAP filter. The
  default is \term{none}. Example:
  \term{"(\&(objectClass=shadowAccount)(memberOf=Jabber Users))"}. Please, do
  not forget to close brackets and do not use superfluous whitespaces. Also you
  \emph{must not} use \option{ldap\_uidattr} attribute in filter because this
  attribute will be substituted in LDAP filter automatically.
\end{description}

\subsubsection{Examples}
\label{ldapexamples}

\paragraph{\aname{ldapcommonexample}{Common example}}

Let's say \term{ldap.example.org} is the name of our LDAP server. We have
users with their passwords in \term{"ou=Users,dc=example,dc=org"} directory.
Also we have addressbook, which contains users emails and their additional
infos in \term{"ou=AddressBook,dc=example,dc=org"} directory.  Corresponding
authentication section should looks like this:

\begin{verbatim}
  %% authentication method
  {auth_method, ldap}.
  %% DNS name of our LDAP server
  {ldap_servers, ["ldap.example.org"]}.
  %% Bind to LDAP server as "cn=Manager,dc=example,dc=org" with password "secret"
  {ldap_rootdn, "cn=Manager,dc=example,dc=org"}.
  {ldap_password, "secret"}.
  %% define the user's base
  {ldap_base, "ou=Users,dc=example,dc=org"}.
  %% We want to authorize users from 'shadowAccount' object class only
  {ldap_filter, "(objectClass=shadowAccount)"}.
\end{verbatim}

Now we want to use users LDAP-info as their vCards.  We have four attributes
defined in our LDAP schema: \term{"mail"} --- email address, \term{"givenName"}
--- first name, \term{"sn"} --- second name, \term{"birthDay"} --- birthday.
Also we want users to search each other.  Let's see how we can set it up:

\begin{verbatim}
  {modules,
    ...
    {mod_vcard_ldap,
     [
      %% We use the same server and port, but want to bind anonymously because
      %% our LDAP server accepts anonymous requests to
      %% "ou=AddressBook,dc=example,dc=org" subtree.
      {ldap_rootdn, ""},
      {ldap_password, ""},
      %% define the addressbook's base
      {ldap_base, "ou=AddressBook,dc=example,dc=org"},
      %% uidattr: user's part of JID is located in the "mail" attribute
      %% uidattr_format: common format for our emails
      {ldap_uids, [{"mail", "%u@mail.example.org"}]},
      %% We have to define empty filter here, because entries in addressbook does not
      %% belong to shadowAccount object class
      {ldap_filter, ""},
      %% Now we want to define vCard pattern
      {ldap_vcard_map,
       [{"NICKNAME", "%u", []}, % just use user's part of JID as his nickname
        {"GIVEN", "%s", ["givenName"]},
        {"FAMILY", "%s", ["sn"]},
        {"FN", "%s, %s", ["sn", "givenName"]}, % example: "Smith, John"
        {"EMAIL", "%s", ["mail"]},
        {"BDAY", "%s", ["birthDay"]}]},
      %% Search form
      {ldap_search_fields,
       [{"User", "%u"},
        {"Name", "givenName"},
        {"Family Name", "sn"},
        {"Email", "mail"},
        {"Birthday", "birthDay"}]},
      %% vCard fields to be reported
      %% Note that JID is always returned with search results
      {ldap_search_reported,
       [{"Full Name", "FN"},
        {"Nickname", "NICKNAME"},
        {"Birthday", "BDAY"}]}
    ]},
    ...
  }.
\end{verbatim}

Note that \modvcardldap{} module checks for the existence of the user before
searching in his information in LDAP.


\paragraph{Active Directory}
\label{ad}
\ind{databases!Active Directory}

Active Directory is just an LDAP-server with predefined attributes. A sample
configuration is shown below:

\begin{verbatim}
  {auth_method, ldap}.
  {ldap_servers, ["office.org"]}.    % List of LDAP servers
  {ldap_base, "DC=office,DC=org"}. % Search base of LDAP directory
  {ldap_rootdn, "CN=Administrator,CN=Users,DC=office,DC=org"}. % LDAP manager
  {ldap_password, "*******"}. % Password to LDAP manager
  {ldap_uids, [{"sAMAccountName"}]}.
  {ldap_filter, "(memberOf=*)"}.

  {modules,
    ...
    {mod_vcard_ldap,
     [{ldap_vcard_map,
       [{"NICKNAME", "%u", []},
        {"GIVEN", "%s", ["givenName"]},
        {"MIDDLE", "%s", ["initials"]},
        {"FAMILY", "%s", ["sn"]},
        {"FN", "%s", ["displayName"]},
        {"EMAIL", "%s", ["mail"]},
        {"ORGNAME", "%s", ["company"]},
        {"ORGUNIT", "%s", ["department"]},
        {"CTRY", "%s", ["c"]},
        {"LOCALITY", "%s", ["l"]},
        {"STREET", "%s", ["streetAddress"]},
        {"REGION", "%s", ["st"]},
        {"PCODE", "%s", ["postalCode"]},
        {"TITLE", "%s", ["title"]},
        {"URL", "%s", ["wWWHomePage"]},
        {"DESC", "%s", ["description"]},
        {"TEL", "%s", ["telephoneNumber"]}]},
      {ldap_search_fields,
       [{"User", "%u"},
        {"Name", "givenName"},
        {"Family Name", "sn"},
        {"Email", "mail"},
        {"Company", "company"},
        {"Department", "department"},
        {"Role", "title"},
        {"Description", "description"},
        {"Phone", "telephoneNumber"}]},
      {ldap_search_reported,
       [{"Full Name", "FN"},
        {"Nickname", "NICKNAME"},
        {"Email", "EMAIL"}]}
    ]},
    ...
  }.
\end{verbatim}


\section{Modules Configuration}
\label{modules}
\ind{modules}

The option \term{modules} defines the list of modules that will be loaded after
\ejabberd{}'s startup. Each entry in the list is a tuple in which the first
element is the name of a module and the second is a list of options for that
module.

Examples:
\begin{itemize}
\item In this example only the module \modecho{} is loaded and no module
  options are specified between the square brackets:
  \begin{verbatim}
  {modules,
   [{mod_echo,      []}
   ]}.
\end{verbatim}
\item In the second example the modules \modecho{}, \modtime{}, and
  \modversion{} are loaded without options. Remark that, besides the last entry,
  all entries end with a comma:
  \begin{verbatim}
  {modules,
   [{mod_echo,      []},
    {mod_time,      []},
    {mod_version,   []}
   ]}.
\end{verbatim}
\end{itemize}

\subsection{Overview}
\label{modoverview}
\ind{modules!overview}\ind{XMPP compliancy}

The following table lists all modules included in \ejabberd{}.

\begin{table}[H]
  \centering
  \begin{tabular}{|l|l|l|l|}
    \hline Module & Feature & Dependencies & Needed for XMPP? \\ 
    \hline \hline \modadhoc{} & Ad-Hoc Commands (\xepref{0050}) &  & No \\ 
    \hline \modannounce{} & Manage announcements & recommends \modadhoc{} & No \\ 
    \hline \modcaps{} &  Request and cache Entity Capabilities (\xepref{0115}) & & No \\ 
    \hline \modconfigure{} & Server configuration using Ad-Hoc & \modadhoc{} & No \\ 
    \hline \moddisco{} & Service Discovery (\xepref{0030}) &  & No \\ 
    \hline \modecho{} & Echoes Jabber packets &  & No \\ 
    \hline \modirc{} & IRC transport &  & No \\ 
    \hline \modlast{} & Last Activity (\xepref{0012}) &  & No \\ 
    \hline \modlastodbc{} & Last Activity (\xepref{0012}) & supported database (*) & No \\ 
    \hline \modmuc{} & Multi-User Chat (\xepref{0045}) &  & No \\ 
    \hline \modmuclog{} & Multi-User Chat room logging & \modmuc{} & No \\ 
    \hline \modoffline{} & Offline message storage &  & No \\ 
    \hline \modofflineodbc{} & Offline message storage & supported database (*) & No \\ 
    \hline \modprivacy{} & Blocking Communications &  & Yes \\ 
    \hline \modprivacyodbc{} & Blocking Communications & supported database (*) & Yes \\ 
    \hline \modprivate{} & Private XML Storage (\xepref{0049}) &  & No \\ 
    \hline \modprivateodbc{} & Private XML Storage (\xepref{0049}) & supported database (*) & No \\ 
    \hline \modproxy{} & SOCKS5 Bytestreams (\xepref{0065}) &  & No\\
    \hline \modpubsub{} & Publish-Subscribe (\xepref{0060}) and PEP (\xepref{0163}) & \modcaps{} & No \\ 
    \hline \modregister{} & In-Band Registration (\xepref{0077}) &  & No \\ 
    \hline \modroster{} & Roster management &  & Yes (**) \\ 
    \hline \modrosterodbc{} & Roster management & supported database (*) & Yes (**) \\ 
    \hline \modservicelog{} & Copy user messages to logger service &  & No \\ 
    \hline \modsharedroster{} & Shared roster management & \modroster{} or & No \\ 
    & & \modrosterodbc{} & \\ 
    \hline \modstats{} & Statistics Gathering (\xepref{0039}) &  & No \\ 
    \hline \modtime{} & Entity Time (\xepref{0090}) &  & No \\ 
    \hline \modvcard{} & vcard-temp (\xepref{0054}) &  & No \\ 
    \hline \modvcardldap{} & vcard-temp (\xepref{0054}) & LDAP server & No \\ 
    \hline \modvcardodbc{} & vcard-temp (\xepref{0054}) & supported database (*) & No \\ 
    \hline \modversion{} & Software Version (\xepref{0092}) &  & No\\
    \hline
  \end{tabular}
\end{table}

\begin{itemize}
\item (*) For a list of supported databases, see section~\ref{database}.
\item (**) This module or a similar one with another database backend is needed for
XMPP compliancy.
\end{itemize}

You can see which database backend each module needs by looking at the suffix:
\begin{itemize}
\item No suffix, this means that the modules uses Erlang's built-in database
  Mnesia as backend.
\item `\_odbc', this means that the module needs a supported database
  (see~\ref{database}) as backend.
\item `\_ldap', this means that the module needs an LDAP server as backend.
\end{itemize}

If you want to,
it is possible to use a relational database to store pieces of
information. You can do this by changing the module name to a name with an
\term{\_odbc} suffix in \ejabberd{} config file. You can use a relational
database for the following data:

\begin{itemize}
\item Last connection date and time: Use \term{mod\_last\_odbc} instead of
  \term{mod\_last}.
\item Offline messages: Use \term{mod\_offline\_odbc} instead of
  \term{mod\_offline}.
\item Rosters: Use \term{mod\_roster\_odbc} instead of \term{mod\_roster}.
\item Users' VCARD: Use \term{mod\_vcard\_odbc} instead of \term{mod\_vcard}.
\item Private XML storage: Use \term{mod\_private\_odbc} instead of \term{mod\_private}.
\item User rules for blocking communications: Use \term{mod\_privacy\_odbc} instead of \term{mod\_privacy}.
\end{itemize}

You can find more
\footahref{http://www.ejabberd.im/contributions}{contributed modules} on the
\ejabberd{} website. Please remember that these contributions might not work or
that they can contain severe bugs and security leaks. Therefore, use them at
your own risk!


\subsection{Common Options}
\label{modcommonoptions}

The following options are used by many modules. Therefore, they are described in
this separate section.

\subsubsection{\option{iqdisc}}
\label{modiqdiscoption}
\ind{options!iqdisc}

Many modules define handlers for processing IQ queries of different namespaces
to this server or to a user (e.\,g.\ to \jid{example.org} or to
\jid{user@example.org}). This option defines processing discipline for
these queries. Possible values are:
\begin{description}
\titem{no\_queue} All queries of a namespace with this processing discipline are
  processed immediately. This also means that no other packets can be processed
  until this one has been completely processed. Hence this discipline is not
  recommended if the processing of a query can take a relatively long time.
\titem{one\_queue} In this case a separate queue is created for the processing
  of IQ queries of a namespace with this discipline. In addition, the processing
  of this queue is done in parallel with that of other packets. This discipline
  is most recommended.
\titem{parallel} For every packet with this discipline a separate Erlang process
  is spawned. Consequently, all these packets are processed in parallel.
  Although spawning of Erlang process has a relatively low cost, this can break
  the server's normal work, because the Erlang emulator has a limit on the
  number of processes (32000 by default).
\end{description}

Example:
\begin{verbatim}
  {modules,
   [
    ...
    {mod_time, [{iqdisc, no_queue}]},
    ...
   ]}.
\end{verbatim}

\subsubsection{\option{host}}
\label{modhostoption}
\ind{options!host}

This option defines the Jabber ID of a service provided by an \ejabberd{} module.
The keyword "@HOST@" is replaced at start time with the real virtual host string.

This example configures
the \ind{modules!\modecho{}}echo module to provide its echoing service 
in the Jabber ID \jid{mirror.example.org}:
    \begin{verbatim}
  {modules,
   [
    ...
    {mod_echo, [{host, "mirror.example.org"}]},
    ...
   ]}.
\end{verbatim}

However, if there are several virtual hosts and this module is enabled in all of them,
the "@HOST@" keyword must be used:
    \begin{verbatim}
  {modules,
   [
    ...
    {mod_echo, [{host, "mirror.@HOST@"}]},
    ...
   ]}.
\end{verbatim}

\subsection{\modannounce{}}
\label{modannounce}
\ind{modules!\modannounce{}}\ind{MOTD}\ind{message of the day}\ind{announcements}

This module enables configured users to broadcast announcements and to set
the message of the day (MOTD).  
Configured users can perform these actions with a
\Jabber{} client either using Ad-hoc commands
or sending messages to specific JIDs.

The Ad-hoc commands are listed in the Server Discovery.
For this feature to work, \modadhoc{} must be enabled.

The specific JIDs where messages can be sent are listed bellow.
The first JID in each entry will apply only to the specified virtual host
\jid{example.org}, while the JID between brackets will apply to all virtual
hosts in ejabberd.
\begin{description}
\titem{example.org/announce/all (example.org/announce/all-hosts/all)} The
  message is sent to all registered users. If the user is online and connected
  to several resources, only the resource with the highest priority will receive
  the message. If the registered user is not connected, the message will be
  stored offline in assumption that \ind{modules!\modoffline{}}offline storage
  (see section~\ref{modoffline}) is enabled.
\titem{example.org/announce/online (example.org/announce/all-hosts/online)}The
  message is sent to all connected users. If the user is online and connected
  to several resources, all resources will receive the message.
\titem{example.org/announce/motd (example.org/announce/all-hosts/motd)}The
  message is set as the message of the day (MOTD) and is sent to users when they
  login. In addition the message is sent to all connected users (similar to
  \term{announce/online}).
\titem{example.org/announce/motd/update (example.org/announce/all-hosts/motd/update)}
  The message is set as message of the day (MOTD) and is sent to users when they
  login. The message is \emph{not sent} to any currently connected user.
\titem{example.org/announce/motd/delete (example.org/announce/all-hosts/motd/delete)}
  Any message sent to this JID removes the existing message of the day (MOTD).
\end{description}

Options:
\begin{description}
\titem{access} \ind{options!access}This option specifies who is allowed to
  send announcements and to set the message of the day (by default, nobody is
  able to send such messages).
\end{description}

Examples:
\begin{itemize}
\item Only administrators can send announcements:
  \begin{verbatim}
  {access, announce, [{allow, admins}]}.

  {modules,
   [
    ...
    {mod_adhoc, []},
    {mod_announce, [{access, announce}]},
    ...
   ]}.
\end{verbatim}
\item Administrators as well as the direction can send announcements:
\begin{verbatim}
  {acl, direction, {user, "big_boss", "example.org"}}.
  {acl, direction, {user, "assistant", "example.org"}}.
  {acl, admins, {user, "admin", "example.org"}}.
  ...
  {access, announce, [{allow, admins},
                      {allow, direction}]}.
  ...
  {modules,
   [
    ...
    {mod_adhoc, []},
    {mod_announce, [{access, announce}]},
    ...
   ]}.
\end{verbatim}
\end{itemize}

Note that \modannounce{} can be resource intensive on large
deployments as it can broadcast lot of messages. This module should be
disabled for instances of \ejabberd{} with hundreds of thousands users.

\subsection{\moddisco{}}
\label{moddisco}
\ind{modules!\moddisco{}}\ind{protocols!XEP-0030: Service Discovery}\ind{protocols!XEP-0011: Jabber Browsing}\ind{protocols!XEP-0094: Agent Information}

This module adds support for Service Discovery (\xepref{0030}). With
this module enabled, services on your server can be discovered by
\Jabber{} clients. Note that \ejabberd{} has no modules with support
for the superseded Jabber Browsing (\xepref{0011}) and Agent Information
(\xepref{0094}). Accordingly, \Jabber{} clients need to have support for
the newer Service Discovery protocol if you want them be able to discover
the services you offer.

Options:
\begin{description}
\iqdiscitem{Service Discovery (\ns{http://jabber.org/protocol/disco\#items} and
  \ns{http://jabber.org/protocol/disco\#info})}
\titem{extra\_domains} \ind{options!extra\_domains}With this option,
  extra domains can be added to the Service Discovery item list.
\end{description}

Examples:
\begin{itemize}
\item To serve a link to the Jabber User Directory on \jid{jabber.org}:
  \begin{verbatim}
  {modules,
   [
    ...
    {mod_disco, [{extra_domains, ["users.jabber.org"]}]},
    ...
   ]}.
\end{verbatim}
\item To serve a link to the transports on another server:
  \begin{verbatim}
  {modules,
   [
    ...
    {mod_disco, [{extra_domains, ["icq.example.com",
                                  "msn.example.com"]}]},
    ...
   ]}.
\end{verbatim}
\item To serve a link to a few friendly servers:
  \begin{verbatim}
  {modules,
   [
    ...
    {mod_disco, [{extra_domains, ["example.org",
                                  "example.com"]}]},
    ...
   ]}.
\end{verbatim}
\end{itemize}


\subsection{\modecho{}}
\label{modecho}
\ind{modules!\modecho{}}\ind{debugging}

This module simply echoes any \Jabber{}
packet back to the sender. This mirror can be of interest for
\ejabberd{} and \Jabber{} client debugging.

Options:
\begin{description}
\hostitem{echo}
\end{description}

Example: Mirror, mirror, on the wall, who is the most beautiful
  of them all?
  \begin{verbatim}
  {modules,
   [
    ...
    {mod_echo, [{host, "mirror.example.org"}]},
    ...
   ]}.
\end{verbatim}

\ifthenelse{\boolean{modhttpbind}}{\input{mod_http_bind.tex}}{}

\ifthenelse{\boolean{modhttpfileserver}}{\input{mod_http_fileserver.tex}}{}

\subsection{\modirc{}}
\label{modirc}
\ind{modules!\modirc{}}\ind{IRC}

This module is an IRC transport that can be used to join channels on IRC
servers.

End user information:
\ind{protocols!groupchat 1.0}\ind{protocols!XEP-0045: Multi-User Chat}
\begin{itemize}
\item A \Jabber{} client with `groupchat 1.0' support or Multi-User
  Chat support (\xepref{0045}) is necessary to join IRC channels.
\item An IRC channel can be joined in nearly the same way as joining a
  \Jabber{} Multi-User Chat room. The difference is that the room name will
  be `channel\%\jid{irc.example.org}' in case \jid{irc.example.org} is
  the IRC server hosting `channel'. And of course the host should point
  to the IRC transport instead of the Multi-User Chat service.
\item You can register your nickame by sending `IDENTIFY password' to \\
  \jid{nickserver!irc.example.org@irc.jabberserver.org}.
\item Entering your password is possible by sending `LOGIN nick password' \\
  to \jid{nickserver!irc.example.org@irc.jabberserver.org}.
\item When using a popular \Jabber{} server, it can occur that no
  connection can be achieved with some IRC servers because they limit the
  number of conections from one IP.
\end{itemize}

Options:
\begin{description}
\hostitem{irc}
\titem{access} \ind{options!access}This option can be used to specify who
  may use the IRC transport (default value: \term{all}).
\titem{default\_encoding} \ind{options!defaultencoding}Set the default IRC encoding (default value: \term{"koi8-r"}).
\end{description}

Examples:
\begin{itemize}
\item In the first example, the IRC transport is available on (all) your
  virtual host(s) with the prefix `\jid{irc.}'. Furthermore, anyone is
  able to use the transport. The default encoding is set to "iso8859-15".
  \begin{verbatim}
  {modules,
   [
    ...
    {mod_irc, [{access, all}, {default_encoding, "iso8859-15"}]},
    ...
   ]}.
\end{verbatim}
\item In next example the IRC transport is available with JIDs with prefix \jid{irc-t.net}.
  Moreover, the transport is only accessible by paying customers registered on
  our domains and on other servers.
  \begin{verbatim}
  {acl, paying_customers, {user, "customer1", "example.net"}}.
  {acl, paying_customers, {user, "customer2", "example.com"}}.
  {acl, paying_customers, {user, "customer3", "example.org"}}.
  ...
  {access, paying_customers, [{allow, paying_customers},
                              {deny, all}]}.
  ...
  {modules,
   [
    ...
    {mod_irc, [{access, paying_customers},
               {host, "irc.example.net"}]},
    ...
   ]}.
\end{verbatim}
\end{itemize}

\subsection{\modlast{}}
\label{modlast}
\ind{modules!\modlast{}}\ind{protocols!XEP-0012: Last Activity}

This module adds support for Last Activity (\xepref{0012}). It can be used to
discover when a disconnected user last accessed the server, to know when a
connected user was last active on the server, or to query the uptime of the
\ejabberd{} server.

Options:
\begin{description}
\iqdiscitem{Last activity (\ns{jabber:iq:last})}
\end{description}

\subsection{\modmuc{}}
\label{modmuc}
\ind{modules!\modmuc{}}\ind{protocols!XEP-0045: Multi-User Chat}\ind{conferencing}

With this module enabled, your server will support Multi-User Chat
(\xepref{0045}). End users will be able to join text conferences.

Some of the features of Multi-User Chat:
\begin{itemize}
\item Sending private messages to room participants.
\item Inviting users.
\item Setting a conference topic.
\item Creating password protected rooms.
\item Kicking and banning participants.
\end{itemize}

The MUC service allows any Jabber ID to register a nickname,
so nobody else can use that nickname in any room in the MUC service.
To register a nickname, open the Service Discovery in your 
Jabber client and Register in the MUC service.

The MUC service allows the service administrator to send a message
to all existing chatrooms. 
To do so, send the message to the Jabber ID of the MUC service.

This module supports clustering and load
balancing. One module can be started per cluster node. Rooms are
distributed at creation time on all available MUC module
instances. The multi-user chat module is clustered but the room
themselves are not clustered nor fault-tolerant: if the node managing a
set of rooms goes down, the rooms disappear and they will be recreated
on an available node on first connection attempt.

Options:
\begin{description}
\hostitem{conference}
\titem{access} \ind{options!access}You can specify who is allowed to use
  the Multi-User Chat service (by default, everyone is allowed to use it).
\titem{access\_create} \ind{options!access\_create}To configure who is
  allowed to create new rooms at the Multi-User Chat service, this option
  can be used (by default, everybody is allowed to create rooms).
\titem{access\_persistent} \ind{options!access\_persistent}To configure who is
  allowed to modify the 'persistent' chatroom option
  (by default, everybody is allowed to modify that option).
\titem{access\_admin} \ind{options!access\_admin}This option specifies
  who is allowed to administrate the Multi-User Chat service (the default
  value is \term{none}, which means that only the room creator can
  administer his room). By sending a message to the service JID,
  administrators can send service messages that will be displayed in every
  active room.

  \titem{history\_size} \ind{options!history\_size}A small history of
  the current discussion is sent to users when they enter the
  room. With this option you can define the number of history messages
  to keep and send to users joining the room. The value is an
  integer. Setting the value to \term{0} disables the history feature
  and, as a result, nothing is kept in memory. The default value is
  \term{20}. This value is global and thus affects all rooms on the
  server.

  \titem{max\_users} \ind{options!max\_users} This option defines at
  the server level, the maximum number of users allowed per MUC
  room. It can be lowered in each room configuration but cannot be
  increased in individual MUC room configuration. The default value is
  200.

  \titem{max\_users\_admin\_threshold}
  \ind{options!max\_users\_admin\_threshold} This option defines the
  number of MUC admins or owners to allow to enter the room even if
  the maximum number of allowed users is reached. The default limits
  is 5. In most cases this default value is the best setting.

  \titem{max\_user\_conferences}
  \ind{options!max\_user\_conferences} This option define the maximum
  number of chat room any given user will be able to join. The default
  is 10. This option is used to prevent possible abuses. Note that
  this is a soft limits: Some users can sometime join more conferences
  in cluster configurations.
 
  \titem{min\_message\_interval} \ind{options!min\_message\_interval}
  This option defines the minimum interval between two messages send
  by a user in seconds. This option is global and valid for all chat
  rooms. A decimal value can be used. When this option is not defined,
  message rate is not limited. This feature can be used to protect a
  MUC service from users abuses and limit number of messages that will
  be broadcasted by the service. A good value for this minimum message
  interval is 0.4 second. If a user tries to send messages faster, an
  error is send back explaining that the message have been discarded
  and describing the reason why the message is not acceptable.
  
  \titem{min\_presence\_interval}
  \ind{options!min\_presence\_interval} This option defines the
  minimum of time between presence changes coming from a given user in
  seconds. This option is global and valid for all chat rooms. A
  decimal value can be used. When this option is not defined, no
  restriction is applied. This option can be used to protect a MUC
  service for users abuses, as fastly changing a user presence will
  result in possible large presence packet broadcast. If a user tries
  to change its presence more often than the specified interval, the
  presence is cached by \ejabberd{} and only the last presence is
  broadcasted to all users in the room after expiration of the
  interval delay. Intermediate presence packets are silently
  discarded. A good value for this option is 4 seconds.

  \titem{default\_room\_opts} \ind{options!default\_room\_opts}This
  option allow to define the desired default room options.  Obviously,
  the room creator can modify the room options at any time.  The
  available room options are: \option{allow\_change\_subj},
  \option{allow\_private\_messages}, \option{allow\_query\_users},
  \option{allow\_user\_invites}, \option{anonymous}, \option{logging},
  \option{members\_by\_default}, \option{members\_only},
  \option{moderated}, \option{password}, \option{password\_protected},
  \option{persistent}, \option{public}, \option{public\_list},
  \option{title}.  All of them can be set to \option{true} or
  \option{false}, except \option{password} and \option{title} which
  are strings.
\end{description}

Examples:
\begin{itemize}
\item In the first example everyone is allowed to use the Multi-User Chat
  service. Everyone will also be able to create new rooms but only the user
  \jid{admin@example.org} is allowed to administrate any room. In this
  example he is also a global administrator. When \jid{admin@example.org}
  sends a message such as `Tomorrow, the \Jabber{} server will be moved
  to new hardware. This will involve service breakdowns around 23:00 UMT.
  We apologise for this inconvenience.' to \jid{conference.example.org},
  it will be displayed in all active rooms. In this example the history
  feature is disabled.
  \begin{verbatim}
  {acl, admins, {user, "admin", "example.org"}}.
  ...
  {access, muc_admins, [{allow, admins}]}.
  ...
  {modules,
   [
    ...
    {mod_muc, [{access, all},
               {access_create, all},
               {access_admin, muc_admins},
               {history_size, 0}]},
    ...
   ]}.
\end{verbatim}
\item In the second example the Multi-User Chat service is only accessible by
  paying customers registered on our domains and on other servers. Of course
  the administrator is also allowed to access rooms. In addition, he is the
  only authority able to create and administer rooms. When
  \jid{admin@example.org} sends a message such as `Tomorrow, the \Jabber{}
  server will be moved to new hardware. This will involve service breakdowns
  around 23:00 UMT. We apologise for this inconvenience.' to
  \jid{conference.example.org}, it will be displayed in all active rooms. No
  \term{history\_size} option is used, this means that the feature is enabled
  and the default value of 20 history messages will be send to the users.
  \begin{verbatim}
  {acl, paying_customers, {user, "customer1", "example.net"}}.
  {acl, paying_customers, {user, "customer2", "example.com"}}.
  {acl, paying_customers, {user, "customer3", "example.org"}}.
  {acl, admins, {user, "admin", "example.org"}}.
  ...
  {access, muc_admins, [{allow, admins},
                        {deny, all}]}.
  {access, muc_access, [{allow, paying_customers},
                        {allow, admins},
                        {deny, all}]}.
  ...
  {modules,
   [
    ...
    {mod_muc, [{access, muc_access},
               {access_create, muc_admins},
               {access_admin, muc_admins}]},
    ...
   ]}.
\end{verbatim}

\item In the following example, MUC anti abuse options are used. A
user cannot send more than one message every 0.4 seconds and cannot
change its presence more than once every 4 seconds. No ACLs are
defined, but some user restriction could be added as well:

  \begin{verbatim}
  ...
  {modules,
   [
    ...
    {mod_muc, [{min_message_interval, 0.4},
               {min_presence_interval, 4}]},
    ...
   ]}.
\end{verbatim}

\item This example shows how to use \option{default\_room\_opts} to make sure
  newly created chatrooms have by default those options.
  \begin{verbatim}
  {modules,
   [
    ...
    {mod_muc, [{access, muc_access},
               {access_create, muc_admins},
               {default_room_options, [
                 {allow_change_subj, false},
                 {allow_query_users, true},
                 {allow_private_messages, true},
                 {members_by_default, false},
                 {title, "New chatroom"},
                 {anonymous, false}
               ]},
               {access_admin, muc_admins}]},
    ...
   ]}.
\end{verbatim}
\end{itemize}

\subsection{\modmuclog{}}
\label{modmuclog}
\ind{modules!\modmuclog{}}

This module enables optional logging of Multi-User Chat (MUC) conversations to
HTML. Once you enable this module, users can join a chatroom using a MUC capable
Jabber client, and if they have enough privileges, they can request the
configuration form in which they can set the option to enable chatroom logging.

Features:
\begin{itemize}
\item Chatroom details are added on top of each page: room title, JID,
  author, subject and configuration.
\item \ind{protocols!RFC 4622: Internationalized Resource Identifiers (IRIs) and Uniform Resource Identifiers (URIs) for the Extensible Messaging and Presence Protocol (XMPP)}
  Room title and JID are links to join the chatroom (using
  \footahref{http://www.ietf.org/rfc/rfc4622.txt}{XMPP URIs}).
\item Subject and chatroom configuration changes are tracked and displayed.
\item Joins, leaves, nick changes, kicks, bans and `/me' are tracked and
  displayed, including the reason if available.
\item Generated HTML files are XHTML 1.0 Transitional and CSS compliant.
\item Timestamps are self-referencing links.
\item Links on top for quicker navigation: Previous day, Next day, Up.
\item CSS is used for style definition, and a custom CSS file can be used.
\item URLs on messages and subjects are converted to hyperlinks.
\item Timezone used on timestamps is shown on the log files.
\item A custom link can be added on top of each page.
\end{itemize}

Options:
\begin{description}
\titem{access\_log}\ind{options!access\_log}
  This option restricts which users are allowed to enable or disable chatroom
  logging. The default value is \term{muc\_admin}. Note for this default setting
  you need to have an access rule for \term{muc\_admin} in order to take effect.
\titem{cssfile}\ind{options!cssfile}
  With this option you can set whether the HTML files should have a custom CSS
  file or if they need to use the embedded CSS file. Allowed values are
  \term{false} and an URL to a CSS file. With the first value, HTML files will
  include the embedded CSS code. With the latter, you can specify the URL of the
  custom CSS file (for example: `http://example.com/my.css'). The default value
  is \term{false}.
\titem{dirtype}\ind{options!dirtype}
  The type of the created directories can be specified with this option. Allowed
  values are \term{subdirs} and \term{plain}. With the first value,
  subdirectories are created for each year and month. With the latter, the
  names of the log files contain the full date, and there are no subdirectories.
  The default value is \term{subdirs}.
\titem{outdir}\ind{options!outdir}
  This option sets the full path to the directory in which the HTML files should
  be stored. Make sure the \ejabberd{} daemon user has write access on that
  directory. The default value is \term{"www/muc"}.
\titem{timezone}\ind{options!timezone}
  The time zone for the logs is configurable with this option. Allowed values
  are \term{local} and \term{universal}. With the first value, the local time,
  as reported to Erlang by the operating system, will be used. With the latter,
  GMT/UTC time will be used. The default value is \term{local}.
\titem{spam\_prevention}\ind{options!spam\_prevention}
  To prevent spam, the \term{spam\_prevention} option adds a special attribute
  to links that prevent their indexation by search engines. The default value
  is \term{true}, which mean that nofollow attributes will be added to user
  submitted links. 
\titem{top\_link}\ind{options!top\_link}
  With this option you can customize the link on the top right corner of each
  log file. The syntax of this option is \term{\{"URL", "Text"\}}. The default
  value is \term{\{"/", "Home"\}}.
\end{description}

Examples:
\begin{itemize}
\item In the first example any chatroom owner can enable logging, and a
  custom CSS file will be used (http://example.com/my.css). Further, the names
  of the log files will contain the full date, and there will be no
  subdirectories. The log files will be stored in /var/www/muclogs, and the
  time zone will be GMT/UTC. Finally, the top link will be
  \verb|<a href="http://www.jabber.ru">Jabber.ru</a>|.
  \begin{verbatim}
  {access, muc, [{allow, all}]}.
  ...
  {modules,
   [
    ...
    {mod_muc_log, [
               {access_log, muc},
               {cssfile, "http://example.com/my.css"},
               {dirtype, plain},
               {outdir, "/var/www/muclogs"},
               {timezone, universal},
               {spam_prevention, true},
               {top_link, {"http://www.jabber.ru", "Jabber.ru"}}
    ]},
    ...
   ]}.
\end{verbatim}
  \item In the second example only \jid{admin1@example.org} and
  \jid{admin2@example.net} can enable logging, and the embedded CSS file will be
  used. Further, the names of the log files will only contain the day (number),
  and there will be subdirectories for each year and month. The log files will
  be stored in /var/www/muclogs, and the local time will be used. Finally, the
  top link will be the default \verb|<a href="/">Home</a>|.
  \begin{verbatim}
  {acl, admins, {user, "admin1", "example.org"}}.
  {acl, admins, {user, "admin2", "example.net"}}.
  ...
  {access, muc_log, [{allow, admins},
                     {deny, all}]}.
  ...
  {modules,
   [
    ...
    {mod_muc_log, [
               {access_log, muc_log},
               {cssfile, false},
               {dirtype, subdirs},
               {outdir, "/var/www/muclogs"},
               {timezone, local}
    ]},
    ...
   ]}.
\end{verbatim}
\end{itemize}

\subsection{\modoffline{}}
\label{modoffline}
\ind{modules!\modoffline{}}

This module implements offline message storage. This means that all messages
sent to an offline user will be stored on the server until that user comes
online again. Thus it is very similar to how email works. Note that
\term{ejabberdctl}\ind{ejabberdctl} has a command to delete expired messages
(see section~\ref{ejabberdctl}).

\begin{description}
  \titem{user\_max\_messages}\ind{options!user\_max\_messages}This option
  is use to set a max number of offline messages per user (quota). Its
  value can be either \term{infinity} or a strictly positive
  integer. The default value is \term{infinity}.
\end{description}


\subsection{\modprivacy{}}
\label{modprivacy}
\ind{modules!\modprivacy{}}\ind{Blocking Communication}\ind{Privacy Rules}\ind{protocols!RFC 3921: XMPP IM}

This module implements Blocking Communication (also known as Privacy Rules)
as defined in section 10 from XMPP IM. If end users have support for it in
their \Jabber{} client, they will be able to:
\begin{quote}
\begin{itemize}
\item Retrieving one's privacy lists.
\item Adding, removing, and editing one's privacy lists.
\item Setting, changing, or declining active lists.
\item Setting, changing, or declining the default list (i.e., the list that
  is active by default).
\item Allowing or blocking messages based on JID, group, or subscription type
  (or globally).
\item Allowing or blocking inbound presence notifications based on JID, group,
  or subscription type (or globally).
\item Allowing or blocking outbound presence notifications based on JID, group,
  or subscription type (or globally).
\item Allowing or blocking IQ stanzas based on JID, group, or subscription type
  (or globally).
\item Allowing or blocking all communications based on JID, group, or
  subscription type (or globally).
\end{itemize}
(from \ahrefurl{http://www.xmpp.org/specs/rfc3921.html\#privacy})
\end{quote}

Options:
\begin{description}
\iqdiscitem{Blocking Communication (\ns{jabber:iq:privacy})}
\end{description}

\subsection{\modprivate{}}
\label{modprivate}
\ind{modules!\modprivate{}}\ind{protocols!XEP-0049: Private XML Storage}\ind{protocols!XEP-0048: Bookmark Storage}

This module adds support for Private XML Storage (\xepref{0049}):
\begin{quote}
Using this method, Jabber entities can store private data on the server and
retrieve it whenever necessary. The data stored might be anything, as long as
it is valid XML. One typical usage for this namespace is the server-side storage
of client-specific preferences; another is Bookmark Storage (\xepref{0048}).
\end{quote}

Options:
\begin{description}
\iqdiscitem{Private XML Storage (\ns{jabber:iq:private})}
\end{description}

\subsection{\modproxy{}}
\label{modproxy}
\ind{modules!\modversion{}}\ind{protocols!XEP-0065: SOCKS5 Bytestreams}

This module implements SOCKS5 Bytestreams (\xepref{0065}).
It allows \ejabberd{} to act as a file transfer proxy between two
XMPP clients.

Options:
\begin{description}
\titem{host}\ind{options!host}This option defines the hostname of the service.
If this option is not set, the prefix `\jid{proxy.}' is added to \ejabberd{}
hostname.
\titem{name}\ind{options!name}Defines Service Discovery name of the service.
Default is \term{"SOCKS5 Bytestreams"}.
\titem{ip}\ind{options!ip}This option specifies which network interface
to listen for. Default is an IP address of the service's DNS name, or,
if fails, \verb|{127,0,0,1}|.
\titem{port}\ind{options!port}This option defines port to listen for
incoming connections. Default is~7777.
\titem{auth\_type}\ind{options!auth\_type}SOCKS5 authentication type.
Possible values are \term{anonymous} and \term{plain}. Default is
\term{anonymous}.
\titem{access}\ind{options!access}Defines ACL for file transfer initiators.
Default is \term{all}.
\titem{max\_connections}\ind{options!max\_connections}Maximum number of
active connections per file transfer initiator. No limit by default.
\titem{shaper}\ind{options!shaper}This option defines shaper for
the file transfer peers. Shaper with the maximum bandwidth will be selected.
Default is \term{none}.
\end{description}

Examples:
\begin{itemize}
\item The simpliest configuration of the module:
  \begin{verbatim}
  {modules,
   [
    ...
    {mod_proxy65, []},
    ...
  ]}.
\end{verbatim}
\item More complicated configuration.
  \begin{verbatim}
  {acl, proxy_users, {server, "example.org"}}.
  {access, proxy65_access, [{allow, proxy_users}, {deny, all}]}.
  ...
  {acl, admin, {user, "admin", "example.org"}}.
  {shaper, normal, {maxrate, 10240}}. %% 10 Kbytes/sec
  {access, proxy65_shaper, [{none, admin}, {normal, all}]}.
  ...
  {modules,
   [
    ...
    {mod_proxy65, [{host, "proxy1.example.org"},
                   {name, "File Transfer Proxy"},
                   {ip, {200,150,100,1}},
                   {port, 7778},
                   {max_connections, 5},
                   {access, proxy65_access},
                   {shaper, proxy65_shaper}]},
    ...
  ]}.
\end{verbatim}
\end{itemize}

\subsection{\modpubsub{}}
\label{modpubsub}
\ind{modules!\modpubsub{}}\ind{protocols!XEP-0060: Publish-Subscribe}

This module offers a Publish-Subscribe Service (\xepref{0060}).
The functionality in \modpubsub{} can be extended using plugins.
The plugin that implements PEP (Personal Eventing via Pubsub) (\xepref{0163})
is enabled by default, and requires \modcaps{}.

Options:
\begin{description}
\hostitem{pubsub}
\titem{access\_createnode} \ind{options!access\_createnode}
  This option restricts which users are allowed to create pubsub nodes using
  ACL and ACCESS. The default value is \term{pubsub\_createnode}. % Not clear enough + do not use abbreviations.
\titem{plugins} To specify which pubsub node plugins to use. If not defined, the default
  pubsub plugin is always used.
\titem{nodetree} To specify which nodetree to use. If not defined, the default pubsub
  nodetree is used. Nodetrees are default and virtual. Only one nodetree can be used
  and is shared by all node plugins. 
%\titem{served\_hosts} \ind{options!served\_hosts}
%  This option allows to create additional pubsub virtual hosts in a single module instance.
\end{description}

Example:
\begin{verbatim}
  {modules,
   [
    ...
    {mod_pubsub, [
                  {access_createnode, pubsub_createnode},
                  {plugins, ["default", "pep"]}
                 ]}
    ...
   ]}.
\end{verbatim}
%                  {served_hosts, ["example.com", "example.org"]}

\subsection{\modregister{}}
\label{modregister}
\ind{modules!\modregister{}}\ind{protocols!XEP-0077: In-Band Registration}\ind{public registration}

This module adds support for In-Band Registration (\xepref{0077}). This protocol
enables end users to use a \Jabber{} client to:
\begin{itemize}
\item Register a new account on the server.
\item Change the password from an existing account on the server.
\item Delete an existing account on the server.
\end{itemize}


Options:
\begin{description}
\titem{access} \ind{options!access}This option can be configured to specify
  rules to restrict registration. If a rule returns `deny' on the requested
  user name, registration for that user name is denied. (there are no
  restrictions by default).
\titem{welcome\_message} \ind{options!welcomem}Set a welcome message that
  is sent to each newly registered account. The first string is the subject, and 
  the second string is the message body.
\titem{registration\_watchers} \ind{options!rwatchers}This option defines a 
  list of JIDs which will be notified each time a new account is registered.
\iqdiscitem{In-Band Registration (\ns{jabber:iq:register})}
\end{description}

Examples:
\begin{itemize}
\item Next example prohibits the registration of too short account names:
\begin{verbatim}
  {acl, shortname, {user_glob, "?"}}.
  {acl, shortname, {user_glob, "??"}}.
  % The same using regexp:
  %{acl, shortname, {user_regexp, "^..?$"}}.
  ...
  {access, register, [{deny, shortname},
                      {allow, all}]}.
  ...
  {modules,
   [
    ...
    {mod_register, [{access, register}]},
    ...
   ]}.
\end{verbatim}
\item The in-band registration of new accounts can be prohibited by changing the
  \option{access} option. If you really want to disable all In-Band Registration
  functionality, that is changing passwords in-band and deleting accounts
  in-band, you have to remove \modregister{} from the modules list. In this
  example all In-Band Registration functionality is disabled:
  \begin{verbatim}
  {access, register, [{deny, all}]}.

  {modules,
   [
    ...
%    {mod_register, [{access, register}]},
    ...
   ]}.
\end{verbatim}
\item Define the welcome message and three registration watchers:
  \begin{verbatim}
  {modules,
   [
    ...
     {mod_register, [
        {welcome_message, {"Welcome!", "Welcome to this Jabber server. For information about Jabber visit http://www.jabber.org"}},
        {registration_watchers, ["admin1@example.org", "admin2@example.org", "boss@example.net"]}
     ]},
    ...
   ]}.
\end{verbatim}
\end{itemize}

\subsection{\modroster{}}
\label{modroster}
\ind{modules!\modroster{}}\ind{roster management}\ind{protocols!RFC 3921: XMPP IM}

This module implements roster management as defined in \footahref{http://www.xmpp.org/specs/rfc3921.html\#roster}{RFC 3921: XMPP IM}.

Options:
\begin{description}
\iqdiscitem{Roster Management (\ns{jabber:iq:roster})}
\end{description}

\subsection{\modservicelog{}}
\label{modservicelog}
\ind{modules!\modservicelog{}}\ind{message auditing}\ind{Bandersnatch}

This module adds support for logging end user packets via a \Jabber{} message
auditing service such as
\footahref{http://www.funkypenguin.co.za/bandersnatch/}{Bandersnatch}. All user
packets are encapsulated in a \verb|<route/>| element and sent to the specified
service(s).

Options:
\begin{description}
\titem{loggers} \ind{options!loggers}With this option a (list of) service(s)
  that will receive the packets can be specified.
\end{description}

Examples:
\begin{itemize}
\item To log all end user packets to the Bandersnatch service running on
  \jid{bandersnatch.example.com}:
  \begin{verbatim}
  {modules,
   [
    ...
    {mod_service_log, [{loggers, ["bandersnatch.example.com"]}]},
    ...
   ]}.
\end{verbatim}
\item To log all end user packets to the Bandersnatch service running on
  \jid{bandersnatch.example.com} and the backup service on 
  \jid{bandersnatch.example.org}:
  \begin{verbatim}
  {modules,
   [
    ...
    {mod_service_log, [{loggers, ["bandersnatch.example.com",
                                  "bandersnatch.example.org"]}]},
    ...
   ]}.
\end{verbatim}
\end{itemize}

\subsection{\modsharedroster{}}
\label{modsharedroster}
\ind{modules!\modsharedroster{}}\ind{shared roster groups}

This module enables you to create shared roster groups. This means that you can
create groups of people that can see members from (other) groups in their
rosters. The big advantages of this feature are that end users do not need to
manually add all users to their rosters, and that they cannot permanently delete
users from the shared roster groups. 
A shared roster group can have members from any Jabber server,
but the presence will only be available from and to members 
of the same virtual host where the group is created.

Shared roster groups can be edited \emph{only} via the Web Admin. Each group
has a unique identification and the following parameters:
\begin{description}
\item[Name] The name of the group, which will be displayed in the roster.
\item[Description] The description of the group. This parameter does not affect
  anything.
\item[Members] A list of full JIDs of group members, entered one per line in
  the Web Admin.
  To put as members all the registered users in the virtual hosts,
  you can use the special directive: @all@.
  Note that this directive is designed for a small server with just a few hundred users.
\item[Displayed groups] A list of groups that will be in the rosters of this
  group's members.
\end{description}

Examples:
\begin{itemize}
\item Take the case of a computer club that wants all its members seeing each
  other in their rosters. To achieve this, they need to create a shared roster
  group similar to next table:
\begin{table}[H]
  \centering
  \begin{tabular}{|l|l|}
    \hline Identification& Group `\texttt{club\_members}'\\
    \hline Name& Club Members\\
    \hline Description& Members from the computer club\\
    \hline Members&
    {\begin{tabular}{l}
        \jid{member1@example.org}\\
        \jid{member2@example.org}\\
        \jid{member3@example.org}
      \end{tabular}
    }\\
    \hline Displayed groups& \texttt{club\_members}\\
    \hline
  \end{tabular}
\end{table}
\item In another case we have a company which has three divisions: Management,
  Marketing and Sales. All group members should see all other members in their
  rosters. Additionally, all managers should have all marketing and sales people
  in their roster. Simultaneously, all marketeers and the whole sales team
  should see all managers. This scenario can be achieved by creating shared
  roster groups as shown in the following table:
\begin{table}[H]
  \centering
  \begin{tabular}{|l|l|l|l|}
    \hline Identification&
    Group `\texttt{management}'&
    Group `\texttt{marketing}'&
    Group `\texttt{sales}'\\
    \hline Name& Management& Marketing& Sales\\
    \hline Description& \\
    Members&
    {\begin{tabular}{l}
        \jid{manager1@example.org}\\
        \jid{manager2@example.org}\\
        \jid{manager3@example.org}\\
        \jid{manager4@example.org}
      \end{tabular}
    }&
    {\begin{tabular}{l}
        \jid{marketeer1@example.org}\\
        \jid{marketeer2@example.org}\\
        \jid{marketeer3@example.org}\\
        \jid{marketeer4@example.org}
      \end{tabular}
    }&
    {\begin{tabular}{l}
        \jid{saleswoman1@example.org}\\
        \jid{salesman1@example.org}\\
        \jid{saleswoman2@example.org}\\
        \jid{salesman2@example.org}
      \end{tabular}
    }\\
    \hline Displayed groups&
    {\begin{tabular}{l}
        \texttt{management}\\
        \texttt{marketing}\\
        \texttt{sales}
      \end{tabular}
    }&
    {\begin{tabular}{l}
        \texttt{management}\\
        \texttt{marketing}
      \end{tabular}
    }&
    {\begin{tabular}{l}
        \texttt{management}\\
        \texttt{sales}
      \end{tabular}
    }\\
    \hline
  \end{tabular}
\end{table}
\end{itemize}

\subsection{\modstats{}}
\label{modstats}
\ind{modules!\modstats{}}\ind{protocols!XEP-0039: Statistics Gathering}\ind{statistics}

This module adds support for Statistics Gathering (\xepref{0039}). This protocol
allows you to retrieve next statistics from your \ejabberd{} deployment:
\begin{itemize}
\item Total number of registered users on the current virtual host (users/total).
\item Total number of registered users on all virtual hosts (users/all-hosts/total).
\item Total number of online users on the current virtual host (users/online).
\item Total number of online users on all virtual hosts (users/all-hosts/online).
\end{itemize}

Options:
\begin{description}
\iqdiscitem{Statistics Gathering (\ns{http://jabber.org/protocol/stats})}
\end{description}

As there are only a small amount of clients (for \ind{Tkabber}example
\footahref{http://tkabber.jabber.ru/}{Tkabber}) and software libraries with
support for this XEP, a few examples are given of the XML you need to send
in order to get the statistics. Here they are:
\begin{itemize}
\item You can request the number of online users on the current virtual host
  (\jid{example.org}) by sending:
  \begin{verbatim}
<iq to='example.org' type='get'>
  <query xmlns='http://jabber.org/protocol/stats'>
    <stat name='users/online'/>
  </query>
</iq>
\end{verbatim}
\item You can request the total number of registered users on all virtual hosts
  by sending:
  \begin{verbatim}
<iq to='example.org' type='get'>
  <query xmlns='http://jabber.org/protocol/stats'>
    <stat name='users/all-hosts/total'/>
  </query>
</iq>
\end{verbatim}
\end{itemize}

\subsection{\modtime{}}
\label{modtime}
\ind{modules!\modtime{}}\ind{protocols!XEP-0090: Entity Time}

This module features support for Entity Time (\xepref{0090}). By using this XEP,
you are able to discover the time at another entity's location.

Options:
\begin{description}
\iqdiscitem{Entity Time (\ns{jabber:iq:time})}
\end{description}

\subsection{\modvcard{}}
\label{modvcard}
\ind{modules!\modvcard{}}\ind{JUD}\ind{Jabber User Directory}\ind{vCard}\ind{protocols!XEP-0054: vcard-temp}

This module allows end users to store and retrieve their vCard, and to retrieve
other users vCards, as defined in vcard-temp (\xepref{0054}). The module also
implements an uncomplicated \Jabber{} User Directory based on the vCards of
these users. Moreover, it enables the server to send its vCard when queried.

Options:
\begin{description}
\hostitem{vjud}
\iqdiscitem{\ns{vcard-temp}}
\titem{search}\ind{options!search}This option specifies whether the search
  functionality is enabled (value: \term{true}) or disabled (value:
  \term{false}). If disabled, the option \term{host} will be ignored and the
  \Jabber{} User Directory service will not appear in the Service Discovery item
  list. The default value is \term{true}.
\titem{matches}\ind{options!matches}With this option, the number of reported
  search results can be limited. If the option's value is set to \term{infinity},
  all search results are reported. The default value is \term{30}.
\titem{allow\_return\_all}\ind{options!allow\_return\_all}This option enables
  you to specify if search operations with empty input fields should return all
  users who added some information to their vCard. The default value is
  \term{false}.
\titem{search\_all\_hosts}\ind{options!search\_all\_hosts}If this option is set
  to \term{true}, search operations will apply to all virtual hosts. Otherwise
  only the current host will be searched. The default value is \term{true}.
  This option is available in \modvcard, but not available in \modvcardodbc.
\end{description}

Examples:
\begin{itemize}
\item In this first situation, search results are limited to twenty items,
  every user who added information to their vCard will be listed when people
  do an empty search, and only users from the current host will be returned:
  \begin{verbatim}
  {modules,
   [
    ...
    {mod_vcard, [{search, true},
                 {matches, 20},
                 {allow_return_all, true},
                 {search_all_hosts, false}]},
    ...
   ]}.
\end{verbatim}
\item The second situation differs in a way that search results are not limited,
  and that all virtual hosts will be searched instead of only the current one:
  \begin{verbatim}
  {modules,
   [
    ...
    {mod_vcard, [{search, true},
                 {matches, infinity},
                 {allow_return_all, true}]},
    ...
   ]}.
\end{verbatim}
\end{itemize}

\subsection{\modvcardldap{}}
\label{modvcardldap}
\ind{modules!\modvcardldap{}}\ind{JUD}\ind{Jabber User Directory}\ind{vCard}\ind{protocols!XEP-0054: vcard-temp}

%TODO: verify if the referers to the LDAP section are still correct

\ejabberd{} can map LDAP attributes to vCard fields. This behaviour is
implemented in the \modvcardldap{} module. This module does not depend on the
authentication method (see~\ref{ldapauth}).

The \modvcardldap{} module has
its own optional parameters. The first group of parameters has the same
meaning as the top-level LDAP parameters to set the authentication method:
\option{ldap\_servers}, \option{ldap\_port}, \option{ldap\_rootdn},
\option{ldap\_password}, \option{ldap\_base}, \option{ldap\_uids}, and
\option{ldap\_filter}. See section~\ref{ldapauth} for detailed information
about these options. If one of these options is not set, \ejabberd{} will look
for the top-level option with the same name.

The second group of parameters
consists of the following \modvcardldap{}-specific options:

\begin{description}
\hostitem{vjud}
\iqdiscitem{\ns{vcard-temp}}
\titem{search}\ind{options!search}This option specifies whether the search
  functionality is enabled (value: \term{true}) or disabled (value:
  \term{false}). If disabled, the option \term{host} will be ignored and the
  \Jabber{} User Directory service will not appear in the Service Discovery item
  list. The default value is \term{true}.
\titem{matches}\ind{options!matches}With this option, the number of reported
  search results can be limited. If the option's value is set to \term{infinity},
  all search results are reported. The default value is \term{30}.
\titem{ldap\_vcard\_map}\ind{options!ldap\_vcard\_map}With this option you can
  set the table that maps LDAP attributes to vCard fields. The format is:
  \term{[{Name\_of\_vCard\_field, Pattern, List\_of\_LDAP\_attributes}, ...]}.\ind{protocols!RFC 2426: vCard MIME Directory Profile}
  \term{Name\_of\_vcard\_field} is the type name of the vCard as defined in
  \footahref{http://www.ietf.org/rfc/rfc2426.txt}{RFC 2426}. \term{Pattern} is a
  string which contains pattern variables \term{"\%u"}, \term{"\%d"} or
  \term{"\%s"}. \term{List\_of\_LDAP\_attributes} is the list containing LDAP
  attributes. The pattern variables \term{"\%s"} will be sequentially replaced
  with the values of LDAP attributes from \term{List\_of\_LDAP\_attributes},
  \term{"\%u"} will be replaced with the user part of a JID, and \term{"\%d"}
  will be replaced with the domain part of a JID. The default is:
  \begin{verbatim}
  [{"NICK", "%u", []},
   {"FN", "%s", ["displayName"]},
   {"LAST", "%s", ["sn"]},
   {"FIRST", "%s", ["givenName"]},
   {"MIDDLE", "%s", ["initials"]},
   {"ORGNAME", "%s", ["o"]},
   {"ORGUNIT", "%s", ["ou"]},
   {"CTRY", "%s", ["c"]},
   {"LOCALITY", "%s", ["l"]},
   {"STREET", "%s", ["street"]},
   {"REGION", "%s", ["st"]},
   {"PCODE", "%s", ["postalCode"]},
   {"TITLE", "%s", ["title"]},
   {"URL", "%s", ["labeleduri"]},
   {"DESC", "%s", ["description"]},
   {"TEL", "%s", ["telephoneNumber"]},
   {"EMAIL", "%s", ["mail"]},
   {"BDAY", "%s", ["birthDay"]},
   {"ROLE", "%s", ["employeeType"]},
   {"PHOTO", "%s", ["jpegPhoto"]}]
\end{verbatim}
\titem{ldap\_search\_fields}\ind{options!ldap\_search\_fields}This option
  defines the search form and the LDAP attributes to search within. The format
  is: \term{[{Name, Attribute}, ...]}. \term{Name} is the name of a search form
  field which will be automatically translated by using the translation
  files (see \term{msgs/*.msg} for available words). \term{Attribute} is the
  LDAP attribute or the pattern \term{"\%u"}. The default is:
  \begin{verbatim}
  [{"User", "%u"},
   {"Full Name", "displayName"},
   {"Given Name", "givenName"},
   {"Middle Name", "initials"},
   {"Family Name", "sn"},
   {"Nickname", "%u"},
   {"Birthday", "birthDay"},
   {"Country", "c"},
   {"City", "l"},
   {"Email", "mail"},
   {"Organization Name", "o"},
   {"Organization Unit", "ou"}]
\end{verbatim}
\titem{ldap\_search\_reported}\ind{options!ldap\_search\_reported}This option
  defines which search fields should be reported. The format is:
  \term{[{Name, vCard\_Name}, ...]}. \term{Name} is the name of a search form
  field which will be automatically translated by using the translation
  files (see \term{msgs/*.msg} for available words). \term{vCard\_Name} is the
  vCard field name defined in the \option{ldap\_vcard\_map} option. The default
  is:
\begin{verbatim}
  [{"Full Name", "FN"},
   {"Given Name", "FIRST"},
   {"Middle Name", "MIDDLE"},
   {"Family Name", "LAST"},
   {"Nickname", "NICK"},
   {"Birthday", "BDAY"},
   {"Country", "CTRY"},
   {"City", "LOCALITY"},
   {"Email", "EMAIL"},
   {"Organization Name", "ORGNAME"},
   {"Organization Unit", "ORGUNIT"}]
\end{verbatim}
\end{description}

%TODO: this examples still should be organised better
Examples:
\begin{itemize}
\item 

Let's say \term{ldap.example.org} is the name of our LDAP server. We have
users with their passwords in \term{"ou=Users,dc=example,dc=org"} directory.
Also we have addressbook, which contains users emails and their additional
infos in \term{"ou=AddressBook,dc=example,dc=org"} directory.  Corresponding
authentication section should looks like this:

\begin{verbatim}
  %% authentication method
  {auth_method, ldap}.
  %% DNS name of our LDAP server
  {ldap_servers, ["ldap.example.org"]}.
  %% We want to authorize users from 'shadowAccount' object class only
  {ldap_filter, "(objectClass=shadowAccount)"}.
\end{verbatim}

Now we want to use users LDAP-info as their vCards. We have four attributes
defined in our LDAP schema: \term{"mail"} --- email address, \term{"givenName"}
--- first name, \term{"sn"} --- second name, \term{"birthDay"} --- birthday.
Also we want users to search each other. Let's see how we can set it up:

\begin{verbatim}
  {modules,
    ...
    {mod_vcard_ldap,
     [
      %% We use the same server and port, but want to bind anonymously because
      %% our LDAP server accepts anonymous requests to
      %% "ou=AddressBook,dc=example,dc=org" subtree.
      {ldap_rootdn, ""},
      {ldap_password, ""},
      %% define the addressbook's base
      {ldap_base, "ou=AddressBook,dc=example,dc=org"},
      %% uidattr: user's part of JID is located in the "mail" attribute
      %% uidattr_format: common format for our emails
      {ldap_uids, [{"mail","%u@mail.example.org"}]},
      %% We have to define empty filter here, because entries in addressbook does not
      %% belong to shadowAccount object class
      {ldap_filter, ""},
      %% Now we want to define vCard pattern
      {ldap_vcard_map,
       [{"NICK", "%u", []}, % just use user's part of JID as his nickname
        {"FIRST", "%s", ["givenName"]},
        {"LAST", "%s", ["sn"]},
        {"FN", "%s, %s", ["sn", "givenName"]}, % example: "Smith, John"
        {"EMAIL", "%s", ["mail"]},
        {"BDAY", "%s", ["birthDay"]}]},
      %% Search form
      {ldap_search_fields,
       [{"User", "%u"},
        {"Name", "givenName"},
        {"Family Name", "sn"},
        {"Email", "mail"},
        {"Birthday", "birthDay"}]},
      %% vCard fields to be reported
      %% Note that JID is always returned with search results
      {ldap_search_reported,
       [{"Full Name", "FN"},
        {"Nickname", "NICK"},
        {"Birthday", "BDAY"}]}
    ]}
    ...
  }.
\end{verbatim}

Note that \modvcardldap{} module checks an existence of the user before
searching his info in LDAP.

\item \term{ldap\_vcard\_map} example:
\begin{verbatim}
  {ldap_vcard_map,
   [{"NICK", "%u", []},
    {"FN", "%s", ["displayName"]},
    {"CTRY", "Russia", []},
    {"EMAIL", "%u@%d", []},
    {"DESC", "%s\n%s", ["title", "description"]}
   ]},
\end{verbatim}
\item \term{ldap\_search\_fields} example:
\begin{verbatim}
  {ldap_search_fields,
   [{"User", "uid"},
    {"Full Name", "displayName"},
    {"Email", "mail"}
   ]},
\end{verbatim}
\item \term{ldap\_search\_reported} example:
\begin{verbatim}
  {ldap_search_reported,
   [{"Full Name", "FN"},
    {"Email", "EMAIL"},
    {"Birthday", "BDAY"},
    {"Nickname", "NICK"}
   ]},
\end{verbatim}
\end{itemize}

\subsection{\modversion{}}
\label{modversion}
\ind{modules!\modversion{}}\ind{protocols!XEP-0092: Software Version}

This module implements Software Version (\xepref{0092}). Consequently, it
answers \ejabberd{}'s version when queried.

Options:
\begin{description}
\titem{show\_os}\ind{options!showos}Should the operating system be revealed or not.
  The default value is \term{true}.
\iqdiscitem{Software Version (\ns{jabber:iq:version})}
\end{description}

\chapter{Managing an \ejabberd{} server}


\section{\term{ejabberdctl}}
\label{ejabberdctl}

\subsection{Commands}
\label{commands}

The \term{ejabberdctl} command line script allows to start, stop and perform 
many other administrative tasks in a local or remote \ejabberd{} server.

When \term{ejabberdctl} is executed without any parameter,
it displays the available options. If there isn't an \ejabberd{} server running, 
the available parameters are:
\begin{description}
\titem{start} Start \ejabberd{} in background mode. This is the default method.
\titem{debug} Attach an Erlang shell to an already existing \ejabberd{} server. This allows to execute commands interactively in the \ejabberd{} server.
\titem{live} Start \ejabberd{} in live mode: the shell keeps attached to the started server, showing log messages and allowing to execute interactive commands.
\end{description}

If there is an \ejabberd{} server running in the system,
\term{ejabberdctl} shows all the available commands in that server.
The more interesting ones are:
\begin{description}
\titem{status} Check the status of the \ejabberd{} server.
\titem{stop} Stop the \ejabberd{} server which is running in the machine.
\titem{reopen-log} If you use a tool to rotate logs, you have to configure it
  so that this command is executed after each rotation.
\titem {backup, restore, install-fallback, dump, load} You can use these
  commands to create and restore backups. 
%%More information about backuping can
%%  be found in section~\ref{backup}.
\titem{import-file, import-dir} \ind{migration from other software}
  These options can be used to migrate from other \Jabber{}/XMPP servers. There
  exist tutorials to \footahref{http://www.ejabberd.im/migrate-to-ejabberd}{migrate from other software to ejabberd}.
\titem{delete-expired-messages} This option can be used to delete old messages
  in offline storage. This might be useful when the number of offline messages
  is very high.
\end{description}

The \term{ejabberdctl} script also allows the argument \term{--node NODENAME}.
This allows to administer a remote node.

The \term{ejabberdctl} administration script can be configured in the file ejabberdctl.cfg.
This file provides detailed information about each configurable option.


\subsection{Erlang runtime system}
\label{erlangconfiguration}

\ejabberd{} is an Erlang/OTP application that runs inside an Erlang runtime system.
This system is configured using environment variables and command line parameters.
The \term{ejabberdctl} administration script uses many of those possibilities.
You can configure some of them with the file \term{ejabberdctl.cfg}, 
which includes detailed description about them.
This section describes for reference purposes 
all the environment variables and command line parameters.

The environment variables:
\begin{description}
  \titem{EJABBERD\_CONFIG\_PATH} 
	Path to the ejabberd configuration file.
  \titem{EJABBERD\_MSGS\_PATH} 
	Path to the directory with translated strings.
  \titem{EJABBERD\_LOG\_PATH} 
	Path to the ejabberd service log file.
  \titem{EJABBERD\_SO\_PATH} 
	Path to the directory with binary system libraries.
  \titem{HOME} 
	Path to the directory that is considered \ejabberd{}'s home.
	This path is used to read the file \term{.erlang.cookie}.
  \titem{ERL\_CRASH\_DUMP} 
	Path to the file where crash reports will be dumped.
  \titem{ERL\_INETRC} 
	Indicates which IP name resolution to use. It is required if using \term{-sname}.
  \titem{ERL\_MAX\_PORTS} 
	Maximum number of simultaneously open Erlang ports.
  \titem{ERL\_MAX\_ETS\_TABLES} 
	Maximum number of ETS and Mnesia tables.
\end{description}

The command line parameters:
\begin{description}
  \titem{-sname ejabberd} 
	The Erlang node will be identified using only the first part
	of the host name, i.\,e. other Erlang nodes outside this domain cannot contact
	this node. This is the preferable option in most cases.
  \titem{-name ejabberd} 
	The Erlang node will be fully identified.
    This is only useful if you plan to setup an \ejabberd{} cluster with nodes in different networks.
  \titem{-kernel inetrc "/etc/ejabberd/inetrc"} 
	Indicates which IP name resolution to use. It is required if using \term{-sname}.
  \titem{-detached} 
        Starts the Erlang system detached from the system console. 
	Useful for running daemons and backgrounds processes. 
  \titem{-noinput} 
	Ensures that the Erlang system never tries to read any input.
	Useful for running daemons and backgrounds processes. 
  \titem{-pa /var/lib/ejabberd/ebin} 
	Specify the directory where Erlang binary files (*.beam) are located.
  \titem{-s ejabberd} 
	Tell Erlang runtime system to start the \ejabberd{} application.
  \titem{-mnesia dir "/var/lib/ejabberd/db/nodename"}
	Specify the Mnesia database directory.
  \titem{-sasl sasl\_error\_logger \{file, "/var/log/ejabberd/sasl.log"\}}
	Path to the Erlang/OTP system log file.
  \titem{+K [true|false]} 
	Kernel polling.
  \titem{-smp [auto|enable|disable]} 
	SMP support.
  \titem{+P 250000} 
	Maximum number of Erlang processes.
  \titem{-remsh ejabberd@localhost} 
	Open an Erlang shell in a remote Erlang node.
\end{description}
Note that some characters need to be escaped when used in shell scripts, for instance \verb|"| and \verb|{}|.
You can find other options in the Erlang manual page (\shell{erl -man erl}).


\section{Web Admin}
\label{webadmin}
\ind{web admin}

The \ejabberd{} Web Admin allows to administer most of \ejabberd{} using a web browser.

This feature is enabled by default:
a \term{ejabberd\_http} listener with the option \term{web\_admin} (see
section~\ref{listened}) is included in the listening ports. Then you can open 
\verb|http://server:port/admin/| in your favourite web browser. You
will be asked to enter the username (the \emph{full} \Jabber{} ID) and password
of an \ejabberd{} user with administrator rights. After authentication
you will see a page similar to figure~\ref{fig:webadmmain}.

\begin{figure}[htbp]
  \centering
  \insimg{webadmmain.png}
  \caption{Top page from the Web Admin}
  \label{fig:webadmmain}
\end{figure}
Here you can edit access restrictions, manage users, create backups,
manage the database, enable/disable ports listened for, view server
statistics,\ldots

Examples:
\begin{itemize}
\item You can serve the Web Admin on the same port as the
  \ind{protocols!XEP-0025: HTTP Polling}HTTP Polling interface. In this example
  you should point your web browser to \verb|http://example.org:5280/admin/| to
  administer all virtual hosts or to
  \verb|http://example.org:5280/admin/server/example.com/| to administer only
  the virtual host \jid{example.com}. Before you get access to the Web Admin
  you need to enter as username, the JID and password from a registered user
  that is allowed to configure \ejabberd{}. In this example you can enter as
  username `\jid{admin@example.net}' to administer all virtual hosts (first
  URL). If you log in with `\jid{admin@example.com}' on \\
  \verb|http://example.org:5280/admin/server/example.com/| you can only
  administer the virtual host \jid{example.com}.
  \begin{verbatim}
  ...
  {acl, admins, {user, "admin", "example.net"}}.
  {host_config, "example.com", [{acl, admins, {user, "admin", "example.com"}}]}.
  {access, configure, [{allow, admins}]}.
  ...
  {hosts, ["example.org"]}.
  ...
  {listen,
   [...
    {5280, ejabberd_http, [http_poll, web_admin]},
    ...
   ]
  }.
\end{verbatim}
\item For security reasons, you can serve the Web Admin on a secured
  connection, on a port differing from the HTTP Polling interface, and bind it
  to the internal LAN IP. The Web Admin will be accessible by pointing your
  web browser to \verb|https://192.168.1.1:5280/admin/|:
  \begin{verbatim}
  ...
  {hosts, ["example.org"]}.
  ...
  {listen,
   [...
    {5270, ejabberd_http,    [http_poll]},
    {5280, ejabberd_http,    [web_admin, {ip, {192, 168, 1, 1}},
                              tls, {certfile, "/usr/local/etc/server.pem"}]},
    ...
   ]
  }.
\end{verbatim}
\end{itemize}


\section{Ad-hoc Commands}
\label{adhoccommands}

If you enable \modconfigure\ and \modadhoc,
you can perform several administrative tasks in \ejabberd{}
with a Jabber client.
The client must support Ad-Hoc Commands (\xepref{0050}),
and you must login in the Jabber server with
an account with proper privileges.


\section{Change Computer Hostname}
\label{changeerlangnodename}

\ejabberd{} uses the distributed Mnesia database. 
Being distributed, Mnesia enforces consistency of its file,
so it stores the name of the Erlang node in it.
The name of an Erlang node includes the hostname of the computer.
So, the name of the Erlang node changes
if you change the name of the machine in which \ejabberd{} runs,
or when you move \ejabberd{} to a different machine.

So, if you want to change the computer hostname where \ejabberd{} is installed,
you must follow these instructions:
\begin{enumerate}
	\item In the old server, backup the Mnesia database using the Web Admin or \term{ejabberdctl}.
	For example: 
\begin{verbatim}
ejabberdctl backup /tmp/ejabberd-oldhost.backup
\end{verbatim}
	\item In the new server, restore the backup file using the Web Admin or \term{ejabberdctl}.
	For example:
\begin{verbatim}
ejabberdctl restore /tmp/ejabberd-oldhost.backup
\end{verbatim}
\end{enumerate}


\chapter{Securing \ejabberd{}}
\section{Firewall Settings}
\label{firewall}
\ind{firewall}\ind{ports}\ind{SASL}\ind{TLS}\ind{clustering!ports}

You need to take the following TCP ports in mind when configuring your firewall:
\begin{table}[H]
  \centering
  \begin{tabular}{|l|l|}
    \hline Port& Description\\
    \hline \hline 5222& Standard port for Jabber/XMPP client connections, plain or STARTTLS.\\
    \hline 5223& Standard port for Jabber client connections using the old SSL method.\\
    \hline 5269& Standard port for Jabber/XMPP server connections.\\
    \hline 4369& Port used by EPMD for communication between Erlang nodes.\\
    \hline port range& Used for connections between Erlang nodes. This range is configurable.\\
    \hline
  \end{tabular}
\end{table}

\section{epmd }
\label{epmd}

\footahref{http://www.erlang.org/doc/man/epmd.html}{epmd (Erlang Port Mapper Daemon)}
is a small name server included in Erlang/OTP 
and used by Erlang programs when establishing distributed Erlang communications. 
\ejabberd{} needs \term{epmd} to use \term{ejabberdctl} and also when clustering \ejabberd{} nodes. 
This small program is automatically started by Erlang, and is never stopped.
If \ejabberd{} is stopped, and there aren't any other Erlang programs 
running in the system, you can safely stop \term{epmd} if you want.

\ejabberd{} runs inside an Erlang node. 
To communicate with \ejabberd{}, the script \term{ejabberdctl} starts a new Erlang node 
and connects to the Erlang node that holds \ejabberd{}.
In order for this communication to work,
\term{epmd} must be running and listening for name requests in the port 4369.
You should block the port 4369 in the firewall,
so only the programs in your machine can access it.

If you build a cluster of several \ejabberd{} instances,
each \ejabberd{} instance is called an \ejabberd{} node.
Those \ejabberd{} nodes use a special Erlang communication method to
build the cluster, and EPMD is again needed listening in the port 4369.
So, if you plan to build a cluster of \ejabberd{} nodes
you must open the port 4369 for the machines involved in the cluster.
Remember to block the port so Internet doesn't have access to it.

Once an Erlang node solved the node name of another Erlang node using EPMD and port 4369,
the nodes communicate directly.
The ports used in this case are random. 
You can limit the range of ports when starting Erlang with a command-line parameter, for example:
\begin{verbatim}
erl ... -kernel inet_dist_listen_min 4370 inet_dist_listen_max 4375
\end{verbatim}


\section{Erlang Cookie}
\label{cookie}

The Erlang cookie is a string with numbers and letters. 
An Erlang node reads the cookie at startup from the command-line parameter \term{-setcookie}
or from a cookie file.
Two Erlang nodes communicate only if they have the same cookie.
Setting a cookie on the Erlang node allows you to structure your Erlang network 
and define which nodes are allowed to connect to which.

Thanks to Erlang cookies, you can prevent access to the Erlang node by mistake,
for example when there are several Erlang nodes running different programs in the same machine.

Setting a secret cookie is a simple method
to difficult unauthorized access to your Erlang node.
However, the cookie system is not ultimately effective 
to prevent unauthorized access or intrusion to an Erlang node.
The communication between Erlang nodes are not encrypted,
so the cookie could be read sniffing the traffic on the network.
The recommended way to secure the Erlang node is to block the port 4369.


\section{Erlang node name}
\label{nodename}

An Erlang node may have a node name.
The name can be short (if indicated with the command-line parameter \term{-sname}) 
or long (if indicated with the parameter \term{-name}). 
Starting an Erlang node with -sname limits the communication between Erlang nodes to the LAN.

Using the option \term{-sname} instead of \term{-name} is a simple method 
to difficult unauthorized access to your Erlang node.
However, it is not ultimately effective  to prevent access to the Erlang node,
because it may be possible to fake the fact that you are on another network 
using a modified version of Erlang \term{epmd}.
The recommended way to secure the Erlang node is to block the port 4369.


\chapter{Clustering}
\label{clustering}
\ind{clustering}

\section{How it Works}
\label{howitworks}
\ind{clustering!how it works}

A \Jabber{} domain is served by one or more \ejabberd{} nodes. These nodes can
be run on different machines that are connected via a network. They all
must have the ability to connect to port 4369 of all another nodes, and must
have the same magic cookie (see Erlang/OTP documentation, in other words the
file \term{\~{}ejabberd/.erlang.cookie} must be the same on all nodes). This is
needed because all nodes exchange information about connected users, s2s
connections, registered services, etc\ldots

Each \ejabberd{} node has the following modules:
\begin{itemize}
\item router,
\item local router,
\item session manager,
\item s2s manager.
\end{itemize}

\subsection{Router}
\label{router}
\ind{clustering!router}

This module is the main router of \Jabber{} packets on each node. It
routes them based on their destination's domains. It uses a global
routing table. The domain of the packet's destination is searched in the
routing table, and if it is found, the packet is routed to the
appropriate process. If not, it is sent to the s2s manager.

\subsection{Local Router}
\label{localrouter}
\ind{clustering!local router}

This module routes packets which have a destination domain equal to
one of this server's host names. If the destination JID has a non-empty user
part, it is routed to the session manager, otherwise it is processed depending
on its content.

\subsection{Session Manager}
\label{sessionmanager}
\ind{clustering!session manager}

This module routes packets to local users. It looks up to which user
resource a packet must be sent via a presence table. Then the packet is
either routed to the appropriate c2s process, or stored in offline
storage, or bounced back.

\subsection{s2s Manager}
\label{s2smanager}
\ind{clustering!s2s manager}

This module routes packets to other \Jabber{} servers. First, it
checks if an opened s2s connection from the domain of the packet's
source to the domain of the packet's destination exists. If that is the case,
the s2s manager routes the packet to the process
serving this connection, otherwise a new connection is opened.

\section{Clustering Setup}
\label{cluster}
\ind{clustering!setup}

Suppose you already configured \ejabberd{} on one machine named (\term{first}),
and you need to setup another one to make an \ejabberd{} cluster. Then do
following steps:

\begin{enumerate}
\item Copy \verb|~ejabberd/.erlang.cookie| file from \term{first} to
  \term{second}.

  (alt) You can also add `\verb|-cookie content_of_.erlang.cookie|'
  option to all `\shell{erl}' commands below.

\item On \term{second} run the following command as the \ejabberd{} daemon user,
  in the working directory of \ejabberd{}:

\begin{verbatim}
erl -sname ejabberd \
    -mnesia extra_db_nodes "['ejabberd@first']" \
    -s mnesia
\end{verbatim}

  This will start Mnesia serving the same database as \node{ejabberd@first}.
  You can check this by running the command `\verb|mnesia:info().|'. You
  should see a lot of remote tables and a line like the following:

\begin{verbatim}
running db nodes   = [ejabberd@first, ejabberd@second]
\end{verbatim}


\item Now run the following in the same `\shell{erl}' session:

\begin{verbatim}
mnesia:change_table_copy_type(schema, node(), disc_copies).
\end{verbatim}

  This will create local disc storage for the database.

  (alt) Change storage type of the \term{scheme} table to `RAM and disc
  copy' on the second node via the Web Admin.


\item Now you can add replicas of various tables to this node with
  `\verb|mnesia:add_table_copy|' or
  `\verb|mnesia:change_table_copy_type|' as above (just replace
  `\verb|schema|' with another table name and `\verb|disc_copies|'
  can be replaced with `\verb|ram_copies|' or
  `\verb|disc_only_copies|').

  Which tables to replicate is very dependant on your needs, you can get
  some hints from the command `\verb|mnesia:info().|', by looking at the
  size of tables and the default storage type for each table on 'first'.

  Replicating a table makes lookups in this table faster on this node.
  Writing, on the other hand, will be slower. And of course if machine with one
  of the replicas is down, other replicas will be used.

  Also \footahref{http://www.erlang.se/doc/doc-5.4.9/lib/mnesia-4.2.2/doc/html/Mnesia\_chap5.html\#5.3}
  {section 5.3 (Table Fragmentation) of Mnesia User's Guide} can be helpful.
  % The above URL needs update every Erlang release!

  (alt) Same as in previous item, but for other tables.


\item Run `\verb|init:stop().|' or just `\verb|q().|' to exit from
  the Erlang shell. This probably can take some time if Mnesia has not yet
  transfered and processed all data it needed from \term{first}.


\item Now run \ejabberd{} on \term{second} with almost the same config as
  on \term{first} (you probably do not need to duplicate `\verb|acl|'
  and `\verb|access|' options --- they will be taken from
  \term{first}, and \verb|mod_muc| and \verb|mod_irc| should be
  enabled only on one machine in the cluster).
\end{enumerate}

You can repeat these steps for other machines supposed to serve this
domain.

\section{Service Load-Balancing}
\subsection{Components Load-Balancing}
\label{componentlb}
\ind{component load-balancing}

\subsection{Domain Load-Balancing Algorithm}
\label{domainlb}
\ind{options!domain\_balancing}

\ejabberd{} includes an algorithm to load balance the components that are plugged on an \ejabberd{} cluster. It means that you can plug one or several instances of the same component on each \ejabberd{} cluster and that the traffic will be automatically distributed.

The default distribution algorithm try to deliver to a local instance of a component. If several local instances are available, one instance is chosen randomly. If no instance is available locally, one instance is chosen randomly among the remote component instances.

If you need a different behaviour, you can change the load balancing behaviour with the option \option{domain\_balancing}. The syntax of the option is the following:

\begin{verbatim}
	{domain_balancing, "component.example.com", <balancing_criterium>}.                                   
\end{verbatim}

Several balancing criteria are available:
\begin{itemize}
\item \term{destination}: the full JID of the packet \term{to} attribute is used.
\item \term{source}: the full JID of the packet \term{from} attribute is used.
\item \term{bare\_destination}: the bare JID (without resource) of the packet \term{to} attribute is used.
\item \term{bare\_source}: the bare JID (without resource) of the packet \term{from} attribute is used.
\end{itemize}

If the value corresponding to the criteria is the same, the same component instance in the cluster will be used.

\subsection{Load-Balancing Buckets}
\label{lbbuckets}
\ind{options!domain\_balancing\_component\_number}

When there is a risk of failure for a given component, domain balancing can cause service trouble. If one component is failing the service will not work correctly unless the sessions are rebalanced.

In this case, it is best to limit the problem to the sessions handled by the failing component. This is what the \term{domain\_balancing\_component\_number} option does, making the load balancing algorithm not dynamic, but sticky on a fix number of component instances.

The syntax is the following:
\begin{verbatim}
    {domain_balancing_component_number, "component.example.com", N}
\end{verbatim}



% TODO
% See also the section about ejabberdctl!!!!
%\section{Backup and Restore}
%\label{backup}
%\ind{backup}

\chapter{Debugging}
\label{debugging}
\ind{debugging}

\section{Watchdog Alerts}
\label{watchdog}
\ind{debugging!watchdog}

\ejabberd{} includes a watchdog mechanism.
If a process in the \ejabberd{} server consumes too much memory,
a message is sent to the Jabber accounts defined with the option
\term{watchdog\_admins}
\ind{options!watchdog\_admins} in the \ejabberd{} configuration file.
Example configuration:
\begin{verbatim}
{watchdog_admins, ["admin2@localhost", "admin2@example.org"]}.
\end{verbatim}


\section{Log Files}
\label{logfiles}

An \ejabberd{} node writes two log files:
\begin{description}
	\titem{ejabberd.log} is the ejabberd service log, with the messages reported by \ejabberd{} code
	\titem{sasl.log} is the Erlang/OTP system log, with the messages reported by Erlang/OTP using SASL (System Architecture Support Libraries)
\end{description}

The option \term{loglevel} modifies the verbosity of the file ejabberd.log.
The possible levels are:
\begin{description}
	\titem{0} No ejabberd log at all (not recommended)
	\titem{1} Critical
	\titem{2} Error
	\titem{3} Warning
	\titem{4} Info
	\titem{5} Debug
\end{description}
For example, the default configuration is:
\begin{verbatim}
{loglevel, 4}.
\end{verbatim}


\section{Debug Console}
\label{debugconsole}

The Debug Console is an Erlang shell attached to an already running \ejabberd{} server.
With this Erlang shell, an experienced administrator can perform complex tasks.

This shell gives complete control over the \ejabberd{} server,
so it is important to use it with extremely care.
There are some simple and safe examples in the article 
\footahref{http://www.ejabberd.im/interconnect-erl-nodes}{Interconnecting Erlang Nodes}

To exit the shell, close the window or press the keys: control+c control+c.


\appendix{}
\chapter{Internationalization and Localization}
\label{i18nl10n}
\ind{xml:lang}\ind{internationalization}\ind{localization}\ind{i18n}\ind{l10n}

All built-in modules support the \texttt{xml:lang} attribute inside IQ queries.
Figure~\ref{fig:discorus}, for example, shows the reply to the following query:
\begin{verbatim}
  <iq id='5'
      to='example.org'
      type='get'
      xml:lang='ru'>
    <query xmlns='http://jabber.org/protocol/disco#items'/>
  </iq>
\end{verbatim}

\begin{figure}[htbp]
  \centering
  \insimg{discorus.png}
  \caption{Service Discovery when \texttt{xml:lang='ru'}}
  \label{fig:discorus}
\end{figure}

The Web Admin also supports the \verb|Accept-Language| HTTP header (compare
figure~\ref{fig:webadmmainru} with figure~\ref{fig:webadmmain})

\begin{figure}[htbp]
  \centering
  \insimg{webadmmainru.png}
  \caption{Top page from the Web Admin with HTTP header
    `Accept-Language: ru'}
  \label{fig:webadmmainru}
\end{figure}


%\section{Ultra Complex Example}
%\label{ultracomplexexample}
%TODO: a very big example covering the whole guide, with a good explanation before the example: different authenticaton mechanisms, transports, ACLs, multple virtual hosts, virtual host specific settings and general settings, modules,...

\chapter{Release Notes}
\label{releasenotes}
\ind{release notes}

Release notes are available from \footahref{http://www.process-one.net/en/ejabberd/release\_notes/}{ejabberd Home Page}

\chapter{Acknowledgements}
\label{acknowledgements}
Thanks to all people who contributed to this guide:
\begin{itemize}
\item Alexey Shchepin (\ahrefurl{xmpp:aleksey@jabber.ru})
\item Badlop (\ahrefurl{xmpp:badlop@jabberes.org})
\item Evgeniy Khramtsov (\ahrefurl{xmpp:xram@jabber.ru})
\item Florian Zumbiehl (\ahrefurl{xmpp:florz@florz.de})
\item Michael Grigutsch (\ahrefurl{xmpp:migri@jabber.i-pobox.net})
\item Mickael Remond (\ahrefurl{xmpp:mremond@erlang-projects.org})
\item Sander Devrieze (\ahrefurl{xmpp:sander@devrieze.dyndns.org})
\item Sergei Golovan (\ahrefurl{xmpp:sgolovan@nes.ru})
\item Vsevolod Pelipas (\ahrefurl{xmpp:vsevoload@jabber.ru})
\end{itemize}


\chapter{Copyright Information}
\label{copyright}

Ejabberd Installation and Operation Guide.\\
Copyright \copyright{} 2003 --- 2008 Process-one

This document is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This document is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with
this document; if not, write to the Free Software Foundation, Inc., 51 Franklin
Street, Fifth Floor, Boston, MA 02110-1301, USA.

%TODO: a glossary describing common terms
%\section{Glossary}}
%\label{glossary}
%\ind{glossary}

%\begin{description}
%\titem{c2s} 
%\titem{s2s}
%\titem{STARTTLS}
%\titem{XEP} (\XMPP{} Extension Protocol)
%\titem{Resource}
%\titem{Roster}
%\titem{Transport}
%\titem{JID} (\Jabber{} ID) <Wikipedia>
%\titem{JUD} (\Jabber{} User Directory)
%\titem{vCard} <Wikipedia>
%\titem{Publish-Subscribe}
%\titem{Namespace}
%\titem{Erlang} <Wikipedia>
%\titem{Fault-tolerant}
%\titem{Distributed} <Wikipedia>
%\titem{Node} <Wikipedia>
%\titem{Tuple} <Wikipedia>
%\titem{Regular Expression}
%\titem{ACL} (Access Control List) <Wikipedia>
%\titem{IPv6} <Wikipedia>
%\titem{Jabber}
%\titem{LDAP} (Lightweight Directory Access Protocol) <Wikipedia>
%\titem{ODBC} (Open Database Connectivity) <Wikipedia>
%\titem{Virtual Hosting} <Wikipedia>

%\end{description}



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