ejabberd 2.1.0-alpha
 
Installation and Operation Guide


Contents

Chapter 1  Introduction

ejabberd is a free and open source instant messaging server written in Erlang.

ejabberd is cross-platform, distributed, fault-tolerant, and based on open standards to achieve real-time communication.

ejabberd is designed to be a rock-solid and feature rich XMPP server.

ejabberd is suitable for small deployments, whether they need to be scalable or not, as well as extremely big deployments.

1.1  Key Features

ejabberd is:

1.2  Additional Features

Moreover, ejabberd comes with a wide range of other state-of-the-art features:

Chapter 2  Installing ejabberd

2.1  Installing ejabberd with Binary Installer

Probably the easiest way to install an ejabberd instant messaging server is using the binary installer published by ProcessOne. The binary installers of released ejabberd versions are available in the ProcessOne ejabberd downloads page: 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: 

chmod +x ejabberd-2.0.0_1-linux-x86-installer.bin
./ejabberd-2.0.0_1-linux-x86-installer.bin

ejabberd can be started manually at any time, or automatically by the operating system at system boot time.

To start and stop ejabberd manually, use the desktop shortcuts created by the installer. If the machine doesn’t have a graphical system, use the scripts ’start’ and ’stop’ in the ’bin’ directory where ejabberd is installed.

The Windows installer also adds ejabberd as a system service, and a shortcut to a debug console for experienced administrators. If you want ejabberd to be started automatically at boot time, go to the Windows service settings and set ejabberd to be automatically started. Note that the Windows service is a feature still in development, and for example it doesn’t read the file ejabberdctl.cfg.

On a *nix system, if you want ejabberd to be started as daemon at boot time, copy ejabberd.init from the ’bin’ directory to something like /etc/init.d/ejabberd (depending on your distribution) and call /etc/inid.d/ejabberd start to start it.

If ejabberd doesn’t start correctly in Windows, try to start it using the shortcut in desktop or start menu. If the window shows error 14001, the solution is to install: "Microsoft Visual C++ 2005 SP1 Redistributable Package". You can download it from www.microsoft.com. Then uninstall ejabberd and install it again.

If ejabberd doesn’t start correctly and a crash dump is generated, there was a severe problem. You can try starting ejabberd with the script bin/live.bat in Windows, or with the command bin/ejabberdctl live in other Operating Systems. This way you see the error message provided by Erlang and can identify what is exactly the problem.

The ejabberdctl administration script is included in the bin directory. Please refer to the section 4.1 for details about ejabberdctl, and configurable options to fine tune the Erlang runtime system.

2.2  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 /etc/init.d/ejabberd to start and stop ejabberd as a service at boot time.

2.3  Installing ejabberd with CEAN

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 ejabberdctl script is located into ejabberd’s priv directory and can be used as an example.

2.4  Installing ejabberd from Source Code

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.

2.4.1  Requirements

To compile ejabberd on a ‘Unix-like’ operating system, you need:

2.4.2  Download Source Code

Released versions of ejabberd are available in the ProcessOne ejabberd downloads page: http://www.process-one.net/en/ejabberd/downloads

Alternatively, the latest development version can be retrieved from the Subversion repository using this command: 

svn co http://svn.process-one.net/ejabberd/trunk ejabberd

2.4.3  Compile

To compile ejabberd execute the commands: 

./configure
make

The build configuration script allows several options. To get the full list run the command: 

./configure --help

Some options that you may be interested in modifying:

--prefix=/
Specify the path prefix where the files will be copied when running the make install command.

--enable-user[=USER]
Allow this normal system user to execute the ejabberdctl script (see section 4.1), read the configuration files, read and write in the spool directory, read and write in the log directory. The account user and group must exist in the machine before running make install. This account doesn’t need an explicit HOME directory, because /var/lib/ejabberd/ will be used by default.

--enable-pam
Enable the PAM authentication method (see section 3.1.4).

--enable-odbc or --enable-mssql
Required if you want to use an external database. See section 3.2 for more information.

--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.

--disable-transient-supervisors
Disable the use of Erlang/OTP supervision for transient processes.

2.4.4  Install

To install ejabberd in the destination directories, run the command: 

make install

Note that you probably need administrative privileges in the system to install ejabberd.

The files and directories created are, by default:

/etc/ejabberd/
Configuration directory:
ejabberd.cfg
ejabberd configuration file
ejabberdctl.cfg
Configuration file of the administration script
inetrc
Network DNS configuration file
/lib/ejabberd/
ebin/
Erlang binary files (*.beam)
include/
Erlang header files (*.hrl)
priv/
Additional files required at runtime
bin/
Executable programs
lib/
Binary system libraries (*.so)
msgs/
Translation files (*.msgs)
/sbin/ejabberdctl
Administration script (see section 4.1)
/share/doc/ejabberd/
Documentation of ejabberd
/var/lib/ejabberd/
Spool directory:
.erlang.cookie
Erlang cookie file (see section 5.3)
acl.DCD, ...
Mnesia database spool files (*.DCD, *.DCL, *.DAT)
/var/log/ejabberd/
Log directory (see section 7.1):
ejabberd.log
ejabberd service log
sasl.log
Erlang/OTP system log

2.4.5  Start

You can use the ejabberdctl command line administration script to start and stop ejabberd. If you provided the configure option --enable-user=USER (see 2.4.3), you can execute ejabberdctl with either that system account or root.

Usage example: 

ejabberdctl start

ejabberdctl status
The node ejabberd@localhost is started with status: started
ejabberd is running in that node

ejabberdctl stop

If ejabberd doesn’t start correctly and a crash dump is generated, there was a severe problem. You can try starting ejabberd with the command ejabberdctl live to see the error message provided by Erlang and can identify what is exactly the problem.

Please refer to the section 4.1 for details about ejabberdctl, and configurable options to fine tune the Erlang runtime system.

2.4.6  Specific Notes for BSD

The command to compile ejabberd in BSD systems is: 

gmake

2.4.7  Specific Notes for Sun Solaris

You need to have GNU install, but it isn’t included in Solaris. It can be easily installed if your Solaris system is set up for blastwave.org package repository. Make sure /opt/csw/bin is in your PATH and run: 

pkg-get -i fileutils

If that program is called ginstall, modify the ejabberd Makefile script to suit your system, for example: 

cat Makefile | sed s/install/ginstall/ > Makefile.gi

And finally install ejabberd with: 

gmake -f Makefile.gi ginstall

2.4.8  Specific Notes for Microsoft Windows

Requirements

To compile ejabberd on a Microsoft Windows system, you need:

Compilation

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

  1. Install Erlang emulator (for example, into C:\sdk\erl5.5.5).
  2. Install Expat library into C:\sdk\Expat-2.0.0 directory.

    Copy file C:\sdk\Expat-2.0.0\Libs\libexpat.dll to your Windows system directory (for example, C:\WINNT or C:\WINNT\System32)

  3. Build and install the Iconv library into the directory C:\sdk\GnuWin32.

    Copy file 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 C:\sdk\Expat-2.0.0\Libs and C:\sdk\GnuWin32\bin to the PATH environment variable.

  4. Install OpenSSL in C:\sdk\OpenSSL and add C:\sdk\OpenSSL\lib\VC to your path or copy the binaries to your system directory.
  5. Install ZLib in C:\sdk\gnuWin32. Copy C:\sdk\GnuWin32\bin\zlib1.dll to your system directory. If you change your path it should already be set after libiconv install.
  6. Make sure the you can access Erlang binaries from your path. For example: set PATH=%PATH%;"C:\sdk\erl5.6.5\bin"
  7. Depending on how you end up actually installing the library you might need to check and tweak the paths in the file configure.erl.
  8. While in the directory ejabberd\src run: 
    configure.bat
nmake -f Makefile.win32
  9. Edit the file ejabberd\src\ejabberd.cfg and run 
    werl -s ejabberd -name ejabberd

2.5  Create a Jabber Account for Administration

You need a Jabber account and grant him administrative privileges to enter the ejabberd Web Admin:

  1. Register a Jabber account on your ejabberd server, for example admin1@example.org. There are two ways to register a Jabber account:
    1. Using ejabberdctl (see section 4.1): 
      ejabberdctl register admin1 example.org FgT5bk3
    2. Using a Jabber client and In-Band Registration (see section 3.3.17).
  2. Edit the ejabberd configuration file to give administration rights to the Jabber account you created: 
    {acl, admins, {user, "admin1", "example.org"}}.
{access, configure, [{allow, admins}]}.
    You can grant administrative privileges to many Jabber accounts, and also to accounts in other Jabber servers.
  3. Restart ejabberd to load the new configuration.
  4. Open the Web Admin (http://server:port/admin/) in your favourite browser. Make sure to enter the full JID as username (in this example: admin1@example.org. The reason that you also need to enter the suffix, is because ejabberd’s virtual hosting support.

2.6  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 3  Configuring ejabberd

3.1  Basic Configuration

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 ‘%’ 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: 

override_global.
override_local.
override_acls.

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.

3.1.1  Host Names

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

Examples:

3.1.2  Virtual Hosting

Options can be defined separately for every virtual host using the host_config option. It has the following syntax: 

{host_config, <hostname>, [<option>, <option>, ...]}.

Examples:

To define specific ejabberd modules in a virtual host, you can define the global modules option with the common modules, and later add specific modules to certain virtual hosts. To accomplish that, instead of defining each option in host_config with the syntax 

{<option-name>, <option-value>}

use this syntax: 

{{add, <option-name>}, <option-value>}

In this example three virtual hosts have some similar modules, but there are also other different modules for some specific virtual hosts: 

%% 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"}]}
                   ]
  }
 ]}.

3.1.3  Listening Ports

The 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:

With the basic syntax the ports will listen on all IPv4 network addresses: 

{listen, [
          {<port-number>, <module>, [<options>]},
          {<port-number>, <module>, [<options>]},
          ...
          {<port-number>, <module>, [<options>]}
         ]}.

It is possible to specify the IP address for a port using the full syntax: 

          {{<port-number>, <ip-address>}, <module>, [<options>]}

Port Number and IP Address

The port number defines which port to listen for incoming connections. It can be a Jabber/XMPP standard port (see section 5.1) or any other valid port number.

The IP address can be represented with a string or an Erlang tuple with decimal or hexadecimal numbers. The socket will listen only in that network interface. It is possible to specify a generic address, so ejabberd will listen in all addresses. Depending in the type of the IP address, IPv4 or IPv6 will be used.

Some example values for IP address:

Listening Module

The available modules, their purpose and the options allowed by each one are:

ejabberd_c2s
Handles c2s connections.
Options: access, certfile, max_stanza_size, shaper, starttls, starttls_required, tls, zlib
ejabberd_s2s_in
Handles incoming s2s connections.
Options: max_stanza_size
ejabberd_service
Interacts with an external component (as defined in the Jabber Component Protocol (XEP-0114).
Options: access, hosts, shaper, service_check_from
ejabberd_http
Handles incoming HTTP connections.
Options: captcha, certfile, http_bind, http_poll, request_handlers, tls, web_admin

Options

This is a detailed description of each option allowed by the listening modules:

{access, <access rule>}
This option defines access to the port. The default value is all.
{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 domain_certfile.
service_check_from
This option can be used with 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 true or false. The default value is true which conforms to XEP-0114.
{hosts, [Hostnames], [HostOptions]}
The external Jabber component that connects to this ejabberd_service can serve one or more hostnames. In HostOptions you can define options for the component; currently the only allowed option is the password required to the component when attempt to connect to ejabberd: {password, Secret}. Note that you cannot define in a single ejabberd_service components of different services: add an ejabberd_service for each service, as seen in an example below.
captcha
Simple web page that allows a user to fill a CAPTCHA challenge (see section 3.1.8).
http_bind
This option enables HTTP Binding (XEP-0124 and XEP-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 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 JWChat (check the tutorials to install JWChat with ejabberd and an embedded local web server or Apache).

http_poll
This option enables HTTP Polling (XEP-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 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 JWChat.

The maximum period of time to keep a client session active without an incoming POST request can be configured with the global option http_poll_timeout. The default value is five minutes. The option can be defined in ejabberd.cfg, expressing the time in seconds: {http_poll_timeout, 300}.

{max_stanza_size, 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 {max_stanza_size, 65536}. The default value is 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.
{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 mod_foo to serve the URIs that start with /a/b/, and you also want mod_http_bind to serve the URIs /http-bind/, use this option: {request_handlers, [{["a", "b"], mod_foo}, {["http-bind"], mod_http_bind}]}
{service_check_from, true|false}
By enabling this option, ejabberd allows the component to send packets with any arbitrary domain in the ’from’ attribute. Note that XEP-0114 requires that the domain must match the hostname of the component. Only enable this option if you are completely sure you need to enable it. Default value: false.
{shaper, <access rule>}
This option defines a shaper for the port (see section 3.1.6). The default value is none.
starttls
This option specifies that STARTTLS encryption is available on connections to the port. You should also set the certfile option. You can define a certificate file for a specific domain using the global option domain_certfile.
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 certfile option. You can define a certificate file for a specific domain using the global option domain_certfile.
tls
This option specifies that traffic on the port will be encrypted using SSL immediately after connecting. This was the traditional encryption method in the early Jabber software, commonly on port 5223 for client-to-server communications. But this method is nowadays deprecated and not recommended. The preferable encryption method is STARTTLS on port 5222, as defined RFC 3920: XMPP Core, which can be enabled in ejabberd with the option starttls. If this option is set, you should also set the certfile option.
web_admin
This option enables the Web Admin for ejabberd administration which is available at 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.
zlib
This option specifies that Zlib stream compression (as defined in XEP-0138) is available on connections to the port. Client connections cannot use stream compression and stream encryption simultaneously. Hence, if you specify both starttls (or tls) and zlib, the latter option will not affect connections (there will be no stream compression).

There are some additional global options that can be specified in the ejabberd configuration file (outside listen):

{s2s_use_starttls, true|false}
This option defines whether to use STARTTLS for s2s connections.
{s2s_certfile, Path}
Full path to a file containing a SSL certificate.
{domain_certfile, Domain, Path}
Full path to the file containing the SSL certificate for a specific domain.
{outgoing_s2s_options, Methods, Timeout}
Specify which address families to try, in what order, and connect timeout in milliseconds. By default it first tries connecting with IPv4, if that fails it tries using IPv6, with a timeout of 10000 milliseconds.
{s2s_default_policy, allow|deny}
The default policy for incoming and outgoing s2s connections to other Jabber servers. The default value is allow.
{{s2s_host, Host}, allow|deny}
Defines if incoming and outgoing s2s connections with a specific remote host are allowed or denied. This allows to restrict ejabberd to only establish s2s connections with a small list of trusted servers, or to block some specific servers.
{s2s_max_retry_delay, Seconds}
The maximum allowed delay for retry to connect after a failed connection attempt. Specified in seconds. The default value is 300 seconds (5 minutes).

Examples

For example, the following simple configuration defines: 

{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, "127.0.0.1"}, 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"}.

In this example, the following configuration defines that: 

{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, {192, 168, 0, 1}}, ejabberd_c2s, [
                                            {access, c2s},
                                            ssl, {certfile, "/path/to/ssl.pem"}
                                           ]},
  {{5223, {16#fdca, 16#8ab6, 16#a243, 16#75ef, 0, 0, 0, 1}},
   ejabberd_c2s, [
                  {access, c2s},
                  ssl, {certfile, "/path/to/ssl.pem"}
                 ]},
  {5269, ejabberd_s2s_in, []},
  {{5280, {0, 0, 0, 0}}, ejabberd_http, [
                                         http_poll,
                                         web_admin
                                        ]},
  {{5233, {127, 0, 0, 1}}, ejabberd_service, [
                                              {hosts, ["aim.example.org"],
                                                 [{password, "aimsecret"}]}
                                             ]},
  {{5233, "::1"}, ejabberd_service, [
                                     {hosts, ["aim.example.org"],
                                        [{password, "aimsecret"}]}
                                    ]},
  {5234, ejabberd_service, [{hosts, ["icq.example.org", "sms.example.org"],
                             [{password, "jitsecret"}]}]},
  {5235, ejabberd_service, [{hosts, ["msn.example.org"],
                             [{password, "msnsecret"}]}]},
  {5236, ejabberd_service, [{hosts, ["yahoo.example.org"],
                             [{password, "yahoosecret"}]}]},
  {5237, ejabberd_service, [{hosts, ["gg.example.org"],
                             [{password, "ggsecret"}]}]},
  {5238, ejabberd_service, [{hosts, ["jmc.example.org"],
                             [{password, "jmcsecret"}]}]},
  {5239, ejabberd_service, [{hosts, ["custom.example.org"],
                             [{password, "customsecret"}]},
                            {service_check_from, false}]}
 ]
}.
{s2s_use_starttls, true}.
{s2s_certfile, "/path/to/ssl.pem"}.
{s2s_default_policy, deny}.
{{s2s_host,"jabber.example.org"}, allow}.
{{s2s_host,"example.com"}, allow}.

Note, that for services based in jabberd14 or WPJabber you have to make the transports log and do XDB by themselves: 

  <!--
     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 jabberd14 -->
      <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>

3.1.4  Authentication

The option auth_method defines the authentication method that is used for user authentication: 

{auth_method, [<method>]}.

The following authentication methods are supported by ejabberd:

Account creation is only supported by internal and odbc methods.

Internal

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

Examples:

SASL Anonymous and Anonymous Login

The anonymous authentication method can be configured with the following options. Remember that you can use the host_config option to set virtual host specific options (see section 3.1.2). Note that there also is a detailed tutorial regarding SASL Anonymous and anonymous login configuration.

Those options are defined for each virtual host with the host_config parameter (see section 3.1.2).

Examples:

PAM Authentication

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: 

./configure --enable-pam && make install

Options:

pam_service
This option defines the PAM service name. Default is "ejabberd". Refer to the PAM documentation of your operation system for more information.

Example: 

{auth_method, [pam]}.
{pam_service, "ejabberd"}.

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

3.1.5  Access Rules

ACL Definition

Access control in ejabberd is performed via Access Control Lists (ACLs). The declarations of ACLs in the configuration file have the following syntax: 

{acl, <aclname>, {<acltype>, ...}}.

<acltype> can be one of the following:

all
Matches all JIDs. Example: 
{acl, all, all}.
{user, <username>}
Matches the user with the name <username> at the first virtual host. Example: 
{acl, admin, {user, "yozhik"}}.
{user, <username>, <server>}
Matches the user with the JID <username>@<server> and any resource. Example: 
{acl, admin, {user, "yozhik", "example.org"}}.
{server, <server>}
Matches any JID from server <server>. Example: 
{acl, exampleorg, {server, "example.org"}}.
{resource, <resource>}
Matches any JID with a resource <resource>. Example: 
{acl, mucklres, {resource, "muckl"}}.
{shared_group, <groupname>}
Matches any member of a Shared Roster Group with name <groupname> in the virtual host. Example: 
{acl, techgroupmembers, {shared_group, "techteam"}}.
{shared_group, <groupname>, <server>}
Matches any member of a Shared Roster Group with name <groupname> in the virtual host <server>. Example: 
{acl, techgroupmembers, {shared_group, "techteam", "example.org"}}.
{user_regexp, <regexp>}
Matches any local user with a name that matches <regexp> on local virtual hosts. Example: 
{acl, tests, {user_regexp, "^test[0-9]*$"}}.
{user_regexp, <regexp>, <server>}
Matches any user with a name that matches <regexp> at server <server>. Example: 
{acl, tests, {user_regexp, "^test", "example.org"}}.
{server_regexp, <regexp>}
Matches any JID from the server that matches <regexp>. Example: 
{acl, icq, {server_regexp, "^icq\\."}}.
{resource_regexp, <regexp>}
Matches any JID with a resource that matches <regexp>. Example: 
{acl, icq, {resource_regexp, "^laptop\\."}}.
{node_regexp, <user_regexp>, <server_regexp>}
Matches any user with a name that matches <user_regexp> at any server that matches <server_regexp>. Example: 
{acl, yohzik, {node_regexp, "^yohzik$", "^example.(com|org)$"}}.
{user_glob, <glob>}
{user_glob, <glob>, <server>}
{server_glob, <glob>}
{resource_glob, <glob>}
{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:
*
matches any string including the null string.
?
matches any single character.
[...]
matches any of the enclosed characters. Character ranges are specified by a pair of characters separated by a ‘-’. If the first character after ‘[’ is a ‘!’, any character not enclosed is matched.

The following ACLs are pre-defined:

all
Matches any JID.
none
Matches no JID.

Access Rights

An entry allowing or denying access to different services looks similar to this: 

{access, <accessname>, [{allow, <aclname>},
                        {deny, <aclname>},
                        ...
                       ]}.

When a JID is checked to have access to <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 ‘deny’ is returned.

Example: 

{access, configure, [{allow, admin}]}.
{access, something, [{deny, badmans},
                     {allow, all}]}.

The following access rules are pre-defined:

all
Always returns the value ‘allow’.
none
Always returns the value ‘deny’.

Limiting Opened Sessions with ACL

The special access 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 session replaced will be sent to the disconnected session. The value for this option can be either a number, or infinity. The default value is infinity.

The syntax is: 

{access, max_user_sessions, [{<maxnumber>, <aclname>},
                             ...
                            ]}.

Examples:

Several connections to a remote Jabber server with ACL

The special access max_s2s_connections specifies how many simultaneus S2S connections can be established to a specific remote Jabber server. The default value is 1. There’s also available the access max_s2s_connections_per_node.

The syntax is: 

{access, max_s2s_connections, [{<maxnumber>, <aclname>},
                               ...
                              ]}.

Examples:

3.1.6  Shapers

Shapers enable you to limit connection traffic. The syntax of shapers is like this: 

{shaper, <shapername>, <kind>}.

Currently only one kind of shaper called maxrate is available. It has the following syntax: 

{maxrate, <rate>}

where <rate> stands for the maximum allowed incoming rate in bytes per second. When a connection exceeds this limit, ejabberd stops reading from the socket until the average rate is again below the allowed maximum.

Examples:

3.1.7  Default Language

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

For example, to set Russian as default language: 

{language, "ru"}.

Appendix A provides more details about internationalization and localization.

3.1.8  CAPTCHA

Some ejabberd modules can be configured to require a CAPTCHA challenge on certain actions. If the client does not support CAPTCHA Forms (XEP-0158), a web link is provided so the user can fill the challenge in a web browser.

An example script is provided that generates the image using ImageMagick’s Convert program.

The configurable options are:

{captcha_cmd, Path}
Full path to a script that generates the image. The default value is an empty string: ""
{captcha_host, Host}
Host part of the URL sent to the user. You can include the port number. The URL sent to the user is formed by: http://Host/captcha/ The default value is the first hostname configured.

Additionally, an ejabberd_http listener must be enabled with the captcha option. See section 3.1.3.

Example configuration: 

{hosts, ["example.org"]}.

{captcha_cmd, "/lib/ejabberd/priv/bin/captcha.sh"}.
{captcha_host, "example.org:5280"}.

{listen,
 [
  ...
  {5280, ejabberd_http, [
                         captcha,
                         ...
                        ]
  }

]}.

3.1.9  Include Additional Configuration Files

The option include_config_file in a configuration file instructs ejabberd to include other configuration files immediately.

The basic usage is: 

{include_config_file, <filename>}.

It is also possible to specify suboptions: 

{include_config_file, <filename>, [<suboption>, <suboption>, ...]}.

The filename can be indicated either as an absolute path, or relative to the main ejabberd configuration file. It isn’t possible to use wildcards. The file must exist and be readable.

The allowed suboptions are:

{disallow, [<option>, <option>, ...]}
Disallows the usage of those options in the included configuration file. The options that match this criteria are not accepted. The default value is an empty list: []
{allow_only, [<option>, <option>, ...]}
Allows only the usage of those options in the included configuration file. The options that do not match this criteria are not accepted. The default value is: all

This is a basic example: 

{include_config_file, "/etc/ejabberd/additional.cfg"}.

In this example, the included file is not allowed to contain a listen option. If such an option is present, the option will not be accepted. The file is in a subdirectory from where the main configuration file is. 

{include_config_file, "./example.org/additional_not_listen.cfg", [{disallow, [listen]}]}.

In this example, ejabberd.cfg defines some ACL and Access rules, and later includes another file with additional rules: 

{acl, admin, {user, "admin", "localhost"}}.
{access, announce, [{allow, admin}]}.
{include_config_file, "/etc/ejabberd/acl_and_access.cfg", [{allow_only, [acl, access]}]}.

and content of the file acl_and_access.cfg can be, for example: 

{acl, admin, {user, "bob", "localhost"}}.
{acl, admin, {user, "jan", "localhost"}}.

3.1.10  Option Macros in Configuration File

In the ejabberd configuration file, it is possible to define a macro for a value and later use this macro when defining an option.

A macro is defined with this syntax: 

{define_macro, '<MACRO>', <value>}.

The MACRO must be surrounded by single quotation marks, and all letters in uppercase; check the examples bellow. The value can be any valid arbitrary Erlang term.

The first definition of a macro is preserved, and additional definitions of the same macro are forgotten.

Macros are processed after additional configuration files have been included, so it is possible to use macros that are defined in configuration files included before the usage.

It isn’t possible to use a macro in the definition of another macro.

There are two ways to use a macro:

’<MACRO>’
You can put this instead of a value in an ejabberd option, and will be replaced with the value previously defined. If the macro is not defined previously, the program will crash and report an error.
{use_macro, ’<MACRO>’, <defaultvalue>}
Use a macro even if it may not be defined. If the macro is not defined previously, the provided defaultvalue is used. This usage behaves as if it were defined and used this way: 
{define_macro, '<MACRO>', <defaultvalue>}.
'<MACRO>'

This example shows the basic usage of a macro: 

{define_macro, 'LOG_LEVEL_NUMBER', 5}.
{loglevel, 'LOG_LEVEL_NUMBER'}.

The resulting option interpreted by ejabberd is: {loglevel, 5}.

This example shows that values can be any arbitrary Erlang term: 

{define_macro, 'USERBOB', {user, "bob", "localhost"}}.
{acl, admin, 'USERBOB'}.

The resulting option interpreted by ejabberd is: {acl, admin, {user, "bob", "localhost"}}.

This complex example: 

{define_macro, 'NUMBER_PORT_C2S', 5222}.
{define_macro, 'PORT_S2S_IN', {5269, ejabberd_s2s_in, []}}.
{listen,
 [
  {'NUMBER_PORT_C2S', ejabberd_c2s, []},
  'PORT_S2S_IN',
  {{use_macro, 'NUMBER_PORT_HTTP', 5280}, ejabberd_http, []}
 ]
}.

produces this result after being interpreted: 

{listen,
 [
  {5222, ejabberd_c2s, []},
  {5269, ejabberd_s2s_in, []},
  {5280, ejabberd_http, []}
 ]
}.

3.2  Database and LDAP Configuration

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:

The following LDAP servers are tested with ejabberd:

Important note about virtual hosting: if you define several domains in ejabberd.cfg (see section 3.1.1), you probably want that each virtual host uses a different configuration of database, authentication and storage, so that usernames do not conflict and mix between different virtual hosts. For that purpose, the options described in the next sections must be set inside a host_config for each vhost (see section 3.1.2). For example: 

{host_config, "public.example.org", [
  {odbc_server, {pgsql, "localhost", "database-public-example-org", "ejabberd", "password"}},
  {auth_method, [odbc]}
]}.

3.2.1  MySQL

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 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.

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.

  1. First, install the 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.
  2. 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: 
    ./configure --enable-odbc && make install

Database Connection

The actual database access is defined in the option 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: 

{mysql, "Server", "Database", "Username", "Password"}

mysql is a keyword that should be kept as is. For example: 

{odbc_server, {mysql, "localhost", "test", "root", "password"}}.

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 mysql parameter can thus take the following form: 

{mysql, "Server", Port, "Database", "Username", "Password"}

The Port value should be an integer, without quotes. For example: 

{odbc_server, {mysql, "localhost", Port, "test", "root", "password"}}.

By default ejabberd opens 10 connections to the database for each virtual host. Use this option to modify the value: 

{odbc_pool_size, 10}.

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. 

{odbc_keepalive_interval, undefined}.

If the connection to the database fails, ejabberd waits 30 seconds before retrying. You can modify this interval with this option: 

{odbc_start_interval, 30}.

Authentication

The option value name may be misleading, as the 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 auth_method. For example: 

{auth_method, [odbc]}.

Storage

MySQL also can be used to store information into from several ejabberd modules. See section 3.3.1 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!

3.2.2  Microsoft SQL Server

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 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.

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: 

./configure --enable-odbc --enable-mssql && make install

Database Connection

By default ejabberd opens 10 connections to the database for each virtual host. Use this option to modify the value: 

{odbc_pool_size, 10}.

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. 

{odbc_keepalive_interval, undefined}.

Authentication

The configuration of Microsoft SQL Server is the same as the configuration of ODBC compatible servers (see section 3.2.4).

Storage

Microsoft SQL Server also can be used to store information into from several ejabberd modules. See section 3.3.1 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!

3.2.3  PostgreSQL

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 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.

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.

  1. First, install the Erlang pgsql library from 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.
  2. 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: 
    ./configure --enable-odbc && make install

Database Connection

The actual database access is defined in the option 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: 

{pgsql, "Server", "Database", "Username", "Password"}

pgsql is a keyword that should be kept as is. For example: 

{odbc_server, {pgsql, "localhost", "database", "ejabberd", "password"}}.

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 pgsql parameter can thus take the following form: 

{pgsql, "Server", Port, "Database", "Username", "Password"}

The Port value should be an integer, without quotes. For example: 

{odbc_server, {pgsql, "localhost", 5432, "database", "ejabberd", "password"}}.

By default ejabberd opens 10 connections to the database for each virtual host. Use this option to modify the value: 

{odbc_pool_size, 10}.

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. 

{odbc_keepalive_interval, undefined}.

Authentication

The option value name may be misleading, as the 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 auth_method. For example: 

{auth_method, [odbc]}.

Storage

PostgreSQL also can be used to store information into from several ejabberd modules. See section 3.3.1 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!

3.2.4  ODBC Compatible

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 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.

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.

  1. First, install the 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.
  2. Then, configure, compile and install ejabberd with ODBC support enabled. This can be done, by using next commands: 
    ./configure --enable-odbc && make install

Database Connection

The actual database access is defined in the option 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 odbc_server parameter. For example: 

{odbc_server, "DSN=database;UID=ejabberd;PWD=password"}.

By default ejabberd opens 10 connections to the database for each virtual host. Use this option to modify the value: 

{odbc_pool_size, 10}.

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. 

{odbc_keepalive_interval, undefined}.

Authentication

The first configuration step is to define the odbc auth_method. For example: 

{auth_method, [odbc]}.

Storage

An ODBC compatible database also can be used to store information into from several ejabberd modules. See section 3.3.1 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!

3.2.5  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.

Note that ejabberd treats LDAP as a read-only storage: it is possible to consult data, but not possible to create accounts, change password or edit vCard that is stored in LDAP.

Connection

Parameters:

ldap_servers
List of IP addresses or DNS names of your LDAP servers. This option is required.
ldap_encrypt
Type of connection encryption to the LDAP server. Allowed values are: none, tls. Note that STARTTLS is not supported. The default value is: none.
ldap_port
Port to connect to your LDAP server. The default port is 389 if encryption is disabled; and 636 if encryption is enabled. 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 port.
ldap_rootdn
Bind DN. The default value is "" which means ‘anonymous connection’.
ldap_password
Bind password. The default value is "".

Example: 

{auth_method, ldap}.
{ldap_servers, ["ldap.example.org"]}.
{ldap_port, 389}.
{ldap_rootdn, "cn=Manager,dc=domain,dc=org"}.
{ldap_password, "secret"}.

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

Authentication

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

ldap_base
LDAP base directory which stores users accounts. This option is required.
ldap_uids
LDAP attribute which holds a list of attributes to use as alternatives for getting the JID. The value is of the form: [{ldap_uidattr}] or [{ldap_uidattr, ldap_uidattr_format}]. You can use as many comma separated tuples {ldap_uidattr, ldap_uidattr_format} that is needed. The default value is [{"uid", "%u"}]. The defaut ldap_uidattr_format is "%u". The values for ldap_uidattr and ldap_uidattr_format are described as follow:
ldap_uidattr
LDAP attribute which holds the user’s part of a JID. The default value is "uid".
ldap_uidattr_format
Format of the ldap_uidattr variable. The format must contain one and only one pattern variable "%u" which will be replaced by the user’s part of a JID. For example, "%u@example.org". The default value is "%u".
ldap_filter
RFC 2254 LDAP filter. The default is none. Example: "(&(objectClass=shadowAccount)(memberOf=Jabber Users))". Please, do not forget to close brackets and do not use superfluous whitespaces. Also you must not use ldap_uidattr attribute in filter because this attribute will be substituted in LDAP filter automatically.
ldap_local_filter
If you can’t use ldap_filter due to performance reasons (the LDAP server has many users registered), you can use this local filter. The local filter checks an attribute in ejabberd, not in LDAP, so this limits the load on the LDAP directory. The default filter is: undefined. Example values: 
{ldap_local_filter, {notequal, {"accountStatus",["disabled"]}}}.
{ldap_local_filter, {equal, {"accountStatus",["enabled"]}}}.
{ldap_local_filter, undefined}.

Examples

Common example

Let’s say ldap.example.org is the name of our LDAP server. We have users with their passwords in "ou=Users,dc=example,dc=org" directory. Also we have addressbook, which contains users emails and their additional infos in "ou=AddressBook,dc=example,dc=org" directory. The connection to the LDAP server is encrypted using TLS, and using the custom port 6123. Corresponding authentication section should looks like this:

%% 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"}.
{ldap_encrypt, tls}.
{ldap_port, 6123}.
%% 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)"}.

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

{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"}]}
  ]},
  ...
 ]}.

Note that mod_vcard_ldap module checks for the existence of the user before searching in his information in LDAP.

Active Directory

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

{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"}]}
  ]},
  ...
 ]}.

3.3  Modules Configuration

The option 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:

3.3.1  Modules Overview

The following table lists all modules included in ejabberd.

ModuleFeatureDependencies
mod_adhocAd-Hoc Commands (XEP-0050) 
mod_announceManage announcementsrecommends mod_adhoc
mod_capsEntity Capabilities (XEP-0115) 
mod_configureServer configuration using Ad-Hocmod_adhoc
mod_discoService Discovery (XEP-0030) 
mod_echoEchoes Jabber packets 
mod_ircIRC transport 
mod_lastLast Activity (XEP-0012) 
mod_last_odbcLast Activity (XEP-0012)supported DB (*)
mod_mucMulti-User Chat (XEP-0045) 
mod_muc_logMulti-User Chat room loggingmod_muc
mod_offlineOffline message storage (XEP-0160) 
mod_offline_odbcOffline message storage (XEP-0160)supported DB (*)
mod_privacyBlocking Communication (XMPP IM) 
mod_privacy_odbcBlocking Communication (XMPP IM)supported DB (*)
mod_privatePrivate XML Storage (XEP-0049) 
mod_private_odbcPrivate XML Storage (XEP-0049)supported DB (*)
mod_proxy65SOCKS5 Bytestreams (XEP-0065) 
mod_pubsubPub-Sub (XEP-0060), PEP (XEP-0163)mod_caps
mod_registerIn-Band Registration (XEP-0077) 
mod_rosterRoster management (XMPP IM) 
mod_roster_odbcRoster management (XMPP IM)supported DB (*)
mod_service_logCopy user messages to logger service 
mod_shared_rosterShared roster managementmod_roster or
  mod_roster_odbc
mod_statsStatistics Gathering (XEP-0039) 
mod_timeEntity Time (XEP-0202) 
mod_vcardvcard-temp (XEP-0054) 
mod_vcard_ldapvcard-temp (XEP-0054)LDAP server
mod_vcard_odbcvcard-temp (XEP-0054)supported DB (*)
mod_versionSoftware Version (XEP-0092) 

You can see which database backend each module needs by looking at the suffix:

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 _odbc suffix in ejabberd config file. You can use a relational database for the following data:

You can find more 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!

3.3.2  Common Options

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

iqdisc

Many modules define handlers for processing IQ queries of different namespaces to this server or to a user (e. g. to example.org or to user@example.org). This option defines processing discipline for these queries. Possible values are:

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.
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.
{queues, N}
N separate queues are created to process the queries. The queries are thus process in parallel, but in a controlled way.
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).

Example: 

{modules,
 [
  ...
  {mod_time, [{iqdisc, no_queue}]},
  ...
 ]}.

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 echo module to provide its echoing service in the Jabber ID mirror.example.org: 

{modules,
 [
  ...
  {mod_echo, [{host, "mirror.example.org"}]},
  ...
 ]}.

However, if there are several virtual hosts and this module is enabled in all of them, the "@HOST@" keyword must be used: 

{modules,
 [
  ...
  {mod_echo, [{host, "mirror.@HOST@"}]},
  ...
 ]}.

3.3.3  mod_announce

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, mod_adhoc 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 example.org, while the JID between brackets will apply to all virtual hosts in ejabberd.

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 offline storage (see section 3.3.12) is enabled.
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.
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 announce/online).
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 not sent to any currently connected user.
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).

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).

Examples:

Note that mod_announce 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.

3.3.4  mod_disco

This module adds support for Service Discovery (XEP-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 (XEP-0011) and Agent Information (XEP-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:

iqdisc
This specifies the processing discipline for Service Discovery (http://jabber.org/protocol/disco#items and http://jabber.org/protocol/disco#info) IQ queries (see section 3.3.2).
{extra_domains, [ Domain ]}
With this option, you can specify a list of extra domains that are added to the Service Discovery item list.
{server_info, [ {Modules, Field, [Value]} ]}
Specify additional information about the server, as described in Contact Addresses for XMPP Services (XEP-0157). Modules can be the keyword ‘all’, in which case the information is reported in all the services; or a list of ejabberd modules, in which case the information is only specified for the services provided by those modules. Any arbitrary Field and Value can be specified, not only contact addresses.

Examples:

3.3.5  mod_echo

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

Options:

host
This option defines the Jabber ID of the service. If the host option is not specified, the Jabber ID will be the hostname of the virtual host with the prefix ‘echo.’. The keyword "@HOST@" is replaced at start time with the real virtual host name.

Example: Mirror, mirror, on the wall, who is the most beautiful of them all? 

{modules,
 [
  ...
  {mod_echo, [{host, "mirror.example.org"}]},
  ...
 ]}.

3.3.6  mod_http_bind

This module implements XMPP over Bosh (formerly known as HTTP Binding) as defined in XEP-0124 and XEP-0206. It extends ejabberd’s built in HTTP service with a configurable resource at which this service will be hosted.

To use HTTP-Binding, enable the module: 

{modules,
 [
  ...
  {mod_http_bind, []},
  ...
]}.

and add http_bind in the HTTP service. For example: 

{listen, 
 [
  ...
  {5280, ejabberd_http, [
                         http_bind,
                         http_poll,
                         web_admin
                        ]
  },
  ...
]}.

With this configuration, the module will serve the requests sent to http://example.org:5280/http-bind/ Remember that this page is not designed to be used by web browsers, it is used by Jabber clients that support XMPP over Bosh.

If you want to set the service in a different URI path or use a different module, you can configure it manually using the option request_handlers. For example: 

{listen, 
 [
  ...
  {5280, ejabberd_http, [
                         {request_handlers, [{["http-bind"], mod_http_bind}]},
                         http_poll,
                         web_admin
                        ]
  },
  ...
]}.

The maximum inactivity period is by default 30 seconds. This can be configured with the module option max_inactivity. For example, to set 50 seconds: 

{modules,
 [
  ...
  {mod_http_bind, [ {max_inactivity, 50} ]},
  ...
]}.

3.3.7  mod_http_fileserver

This simple module serves files from the local disk over HTTP.

Options:

docroot
Directory to serve the files.
accesslog
File to log accesses using an Apache-like format. No log will be recorded if this option is not specified.
directory_indices
Indicate one or more directory index files, similarly to Apache’s DirectoryIndex variable. When a web request hits a directory instead of a regular file, those directory indices are looked in order, and the first one found is returned.
content_types
Specify a mapping of extensions to content types. There are several content types already defined, with this option you can add new definitions, modify or delete existing ones. To delete an existing definition, simply define it with a value: ‘undefined’.
default_content_type
Specify the content type to use for unknown extensions. Default value is ‘application/octet-stream’.

This example configuration will serve the files from the local directory /var/www in the address http://example.org:5280/pub/archive/. In this example a new content type ogg is defined, png is redefined, and jpg definition is deleted. To use this module you must enable it: 

{modules,
 [
  ...
  {mod_http_fileserver, [
                         {docroot, "/var/www"}, 
                         {accesslog, "/var/log/ejabberd/access.log"},
                         {directory_indices, ["index.html", "main.htm"]},
                         {content_types, [{".ogg", "audio/ogg"},
                                          {".png", "image/png"},
                                          {".jpg", undefined}
                                         ]},
                         {default_content_type, "text/html"}
                        ]
  },
  ...
]}.

And define it as a handler in the HTTP service: 

{listen, 
 [
  ...
  {5280, ejabberd_http, [
                         ...
                         {request_handlers, [
                                             ...
                                             {["pub", "archive"], mod_http_fileserver},
                                             ...
                                            ]
                         },
                         ...
                        ]
  },
  ...
]}.

3.3.8  mod_irc

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

End user information:

Options:

host
This option defines the Jabber ID of the service. If the host option is not specified, the Jabber ID will be the hostname of the virtual host with the prefix ‘irc.’. The keyword "@HOST@" is replaced at start time with the real virtual host name.
access
This option can be used to specify who may use the IRC transport (default value: all).
default_encoding
Set the default IRC encoding (default value: "koi8-r").

Examples:

3.3.9  mod_last

This module adds support for Last Activity (XEP-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:

iqdisc
This specifies the processing discipline for Last activity (jabber:iq:last) IQ queries (see section 3.3.2).

3.3.10  mod_muc

This module provides a Multi-User Chat (XEP-0045) service. Users can discover existing rooms, join or create them. Occupants of a room can chat in public or have private chats.

Some of the features of Multi-User Chat:

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.

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 rooms 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.

Module options:

host
This option defines the Jabber ID of the service. If the host option is not specified, the Jabber ID will be the hostname of the virtual host with the prefix ‘conference.’. The keyword "@HOST@" is replaced at start time with the real virtual host name.
access
You can specify who is allowed to use the Multi-User Chat service. By default everyone is allowed to use it.
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.
access_persistent
To configure who is allowed to modify the ’persistent’ room option. By default everybody is allowed to modify that option.
access_admin
This option specifies who is allowed to administrate the Multi-User Chat service. The default value is none, which means that only the room creator can administer his room. The administrators can send a normal message to the service JID, and it will be shown in all active rooms as a service message. The administrators can send a groupchat message to the JID of an active room, and the message will be shown in the room as a service message.
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 0 disables the history feature and, as a result, nothing is kept in memory. The default value is 20. This value is global and thus affects all rooms on the service.
max_users
This option defines at the service level, the maximum number of users allowed per room. It can be lowered in each room configuration but cannot be increased in individual room configuration. The default value is 200.
max_users_admin_threshold
This option defines the number of service admins or room owners allowed to enter the room when the maximum number of allowed occupants was reached. The default limit is 5.
max_user_conferences
This option defines the maximum number of rooms that any given user can join. The default value is 10. This option is used to prevent possible abuses. Note that this is a soft limit: some users can sometimes join more conferences in cluster configurations.
max_room_id
This option defines the maximum number of characters that Room ID can have when creating a new room. The default value is to not limit: infinite.
max_room_name
This option defines the maximum number of characters that Room Name can have when configuring the room. The default value is to not limit: infinite.
max_room_desc
This option defines the maximum number of characters that Room Description can have when configuring the room. The default value is to not limit: infinite.
min_message_interval
This option defines the minimum interval between two messages send by an occupant in seconds. This option is global and valid for all 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 occupant 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 an occupant tries to send messages faster, an error is send back explaining that the message has been discarded and describing the reason why the message is not acceptable.
min_presence_interval
This option defines the minimum of time between presence changes coming from a given occupant in seconds. This option is global and valid for all 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 occupants abuses. If an occupant 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 occupants in the room after expiration of the interval delay. Intermediate presence packets are silently discarded. A good value for this option is 4 seconds.
default_room_options
This module option allows to define the desired default room options. Note that the creator of a room can modify the options of his room at any time using a Jabber client with MUC capability. The available room options and the default values are:
{allow_change_subj, true}
Allow occupants to change the subject.
{allow_private_messages, true}
Occupants can send private messages to other occupants.
{allow_query_users, true}
Occupants can send IQ queries to other occupants.
{allow_user_invites, false}
Allow occupants to send invitations.
{allow_visitor_nickchange, true}
Allow visitors to change nickname.
{allow_visitor_status, true}
Allow visitors to send status text in presence updates. If disallowed, the status text is stripped before broadcasting the presence update to all the room occupants.
{anonymous, true}
The room is anonymous: occupants don’t see the real JIDs of other occupants. Note that the room moderators can always see the real JIDs of the occupants.
{logging, false}
The public messages are logged using mod_muc_log.
{max_users, 200}
Maximum number of occupants in the room.
{members_by_default, true}
The occupants that enter the room are participants by default, so they have ’voice’.
{members_only, false}
Only members of the room can enter.
{moderated, true}
Only occupants with ’voice’ can send public messages.
{password, ""}
Password of the room. You may want to enable the next option too.
{password_protected, false}
The password is required to enter the room.
{persistent, false}
The room persists even if the last participant leaves.
{public, true}
The room is public in the list of the MUC service, so it can be discovered.
{public_list, true}
The list of participants is public, without requiring to enter the room.
{title, ""}
A human-readable title of the room.
All of those room options can be set to true or false, except password and title which are strings, and max_users that is integer.

Examples:

3.3.11  mod_muc_log

This module enables optional logging of Multi-User Chat (MUC) public conversations to HTML. Once you enable this module, users can join a room 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 room logging.

Features:

Options:

access_log
This option restricts which occupants are allowed to enable or disable room logging. The default value is muc_admin. Note for this default setting you need to have an access rule for muc_admin in order to take effect.
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 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 false.
dirname
Allows to configure the name of the room directory. Allowed values are room_jid and room_name. With the first value, the room directory name will be the full room JID. With the latter, the room directory name will be only the room name, not including the MUC service name. The default value is room_jid.
dirtype
The type of the created directories can be specified with this option. Allowed values are subdirs and 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 subdirs.
file_format
Define the format of the log files: html stores in HTML format, plaintext stores in plain text. The default value is html.
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 "www/muc".
spam_prevention
To prevent spam, the spam_prevention option adds a special attribute to links that prevent their indexation by search engines. The default value is true, which mean that nofollow attributes will be added to user submitted links.
timezone
The time zone for the logs is configurable with this option. Allowed values are local and 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 local.
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 {"URL", "Text"}. The default value is {"/", "Home"}.

Examples:

3.3.12  mod_offline

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 ejabberdctl has a command to delete expired messages (see section 4.1).

access_max_user_messages
This option defines which access rule will be enforced to limit the maximum number of offline messages that a user can have (quota). When a user has too many offline messages, any new messages that he receive are discarded, and a resource-constraint error is returned to the sender. The default value is max_user_offline_messages. Then you can define an access rule with a syntax similar to max_user_sessions (see 3.1.5).

This example allows power users to have as much as 5000 offline messages, administrators up to 2000, and all the other users up to 100. 

{acl, admin, {user, "admin1", "localhost"}}.
{acl, admin, {user, "admin2", "example.org"}}.
{acl, poweruser, {user, "bob", "example.org"}}.
{acl, poweruser, {user, "jane", "example.org"}}.

{access, max_user_offline_messages, [ {5000, poweruser}, {2000, admin}, {100, all} ]}.

{modules,
 [
  ...
  {mod_offline,  [ {access_max_user_messages, max_user_offline_messages} ]},
  ...
 ]}.

3.3.13  mod_privacy

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:

(from http://www.xmpp.org/specs/rfc3921.html#privacy)

Options:

iqdisc
This specifies the processing discipline for Blocking Communication (jabber:iq:privacy) IQ queries (see section 3.3.2).

3.3.14  mod_private

This module adds support for Private XML Storage (XEP-0049):

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 (XEP-0048).

Options:

iqdisc
This specifies the processing discipline for Private XML Storage (jabber:iq:private) IQ queries (see section 3.3.2).

3.3.15  mod_proxy65

This module implements SOCKS5 Bytestreams (XEP-0065). It allows ejabberd to act as a file transfer proxy between two XMPP clients.

Options:

host
This option defines the hostname of the service. If this option is not set, the prefix ‘proxy.’ is added to ejabberd hostname.
name
Defines Service Discovery name of the service. Default is "SOCKS5 Bytestreams".
ip
This option specifies which network interface to listen for. Default is an IP address of the service’s DNS name, or, if fails, {127,0,0,1}.
port
This option defines port to listen for incoming connections. Default is 7777.
auth_type
SOCKS5 authentication type. Possible values are anonymous and plain. Default is anonymous.
access
Defines ACL for file transfer initiators. Default is all.
max_connections
Maximum number of active connections per file transfer initiator. No limit by default.
shaper
This option defines shaper for the file transfer peers. Shaper with the maximum bandwidth will be selected. Default is none.

Examples:

3.3.16  mod_pubsub

This module offers a Publish-Subscribe Service (XEP-0060). The functionality in mod_pubsub can be extended using plugins. The plugin that implements PEP (Personal Eventing via Pubsub) (XEP-0163) is enabled in the default ejabberd configuration file, and it requires mod_caps.

Options:

host
This option defines the Jabber ID of the service. If the host option is not specified, the Jabber ID will be the hostname of the virtual host with the prefix ‘pubsub.’. The keyword "@HOST@" is replaced at start time with the real virtual host name.
access_createnode
This option restricts which users are allowed to create pubsub nodes using ACL and ACCESS. The default value is pubsub_createnode.
plugins
To specify which pubsub node plugins to use. If not defined, the default pubsub plugin is always used.
nodetree
To specify which nodetree to use. If not defined, the default pubsub nodetree is used. Only one nodetree can be used per host, and is shared by all node plugins.
pep_sendlast_offline
To specify whether or not we should get last published PEP items from users in our roster which are offline when we connect. Value is true or false. If not defined, pubsub assumes false so we only get last items of online contacts.
last_item_cache
To specify whether or not pubsub should cache last items. Value is true or false. If not defined, pubsub do not cache last items. On systems with not so many nodes, caching last items speeds up pubsub and allows to raise user connection rate. The cost is memory usage, as every item is stored in memory.
pep_mapping
This allow to define a Key-Value list to choose defined node plugins on given PEP namespace. The following example will use node_tune instead of node_pep for every PEP node with tune namespace: 
  {mod_pubsub, [{pep_mapping, [{"http://jabber.org/protocol/tune", "tune"}]}]}

Example: 

{modules,
 [
  ...
  {mod_pubsub, [
                {access_createnode, pubsub_createnode},
                {plugins, ["default", "pep"]}
               ]}
  ...
 ]}.

3.3.17  mod_register

This module adds support for In-Band Registration (XEP-0077). This protocol enables end users to use a Jabber client to:

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).
welcome_message
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. In the body you can set a newline with the characters: \n
registration_watchers
This option defines a list of JIDs which will be notified each time a new account is registered.
iqdisc
This specifies the processing discipline for In-Band Registration (jabber:iq:register) IQ queries (see section 3.3.2).

This module reads also another option defined globally for the server: {registration_timeout, Timeout}. This option limits the frequency of registration from a given IP or username. So, a user can’t register a new account from the same IP address or JID during this number of seconds after previous registration. Timeout is expressed in seconds, and must be an integer. To disable this limitation, instead of an integer put a word like: infinity. Default value: 600 seconds.

Examples:

3.3.18  mod_roster

This module implements roster management as defined in RFC 3921: XMPP IM.

Options:

iqdisc
This specifies the processing discipline for Roster Management (jabber:iq:roster) IQ queries (see section 3.3.2).

3.3.19  mod_service_log

This module adds support for logging end user packets via a Jabber message auditing service such as Bandersnatch. All user packets are encapsulated in a <route/> element and sent to the specified service(s).

Options:

loggers
With this option a (list of) service(s) that will receive the packets can be specified.

Examples:

3.3.20  mod_shared_roster

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 only via the Web Admin. Each group has a unique identification and the following parameters:

Name
The name of the group, which will be displayed in the roster.
Description
The description of the group. This parameter does not affect anything.
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.
Displayed groups
A list of groups that will be in the rosters of this group’s members.

Examples:

3.3.21  mod_stats

This module adds support for Statistics Gathering (XEP-0039). This protocol allows you to retrieve next statistics from your ejabberd deployment:

Options:

iqdisc
This specifies the processing discipline for Statistics Gathering (http://jabber.org/protocol/stats) IQ queries (see section 3.3.2).

As there are only a small amount of clients (for example 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:

3.3.22  mod_time

This module features support for Entity Time (XEP-0202). By using this XEP, you are able to discover the time at another entity’s location.

Options:

iqdisc
This specifies the processing discipline for Entity Time (jabber:iq:time) IQ queries (see section 3.3.2).

3.3.23  mod_vcard

This module allows end users to store and retrieve their vCard, and to retrieve other users vCards, as defined in vcard-temp (XEP-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:

host
This option defines the Jabber ID of the service. If the host option is not specified, the Jabber ID will be the hostname of the virtual host with the prefix ‘vjud.’. The keyword "@HOST@" is replaced at start time with the real virtual host name.
iqdisc
This specifies the processing discipline for vcard-temp IQ queries (see section 3.3.2).
search
This option specifies whether the search functionality is enabled (value: true) or disabled (value: false). If disabled, the option host will be ignored and the Jabber User Directory service will not appear in the Service Discovery item list. The default value is true.
matches
With this option, the number of reported search results can be limited. If the option’s value is set to infinity, all search results are reported. The default value is 30.
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 false.
search_all_hosts
If this option is set to true, search operations will apply to all virtual hosts. Otherwise only the current host will be searched. The default value is true. This option is available in mod_vcard, but not available in mod_vcard_odbc.

Examples:

3.3.24  mod_vcard_ldap

ejabberd can map LDAP attributes to vCard fields. This behaviour is implemented in the mod_vcard_ldap module. This module does not depend on the authentication method (see 3.2.5).

Note that ejabberd treats LDAP as a read-only storage: it is possible to consult data, but not possible to create accounts, change password or edit vCard that is stored in LDAP.

The mod_vcard_ldap 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: ldap_servers, ldap_port, ldap_rootdn, ldap_password, ldap_base, ldap_uids, and ldap_filter. See section 3.2.5 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 mod_vcard_ldap-specific options:

host
This option defines the Jabber ID of the service. If the host option is not specified, the Jabber ID will be the hostname of the virtual host with the prefix ‘vjud.’. The keyword "@HOST@" is replaced at start time with the real virtual host name.
iqdisc
This specifies the processing discipline for vcard-temp IQ queries (see section 3.3.2).
search
This option specifies whether the search functionality is enabled (value: true) or disabled (value: false). If disabled, the option host will be ignored and the Jabber User Directory service will not appear in the Service Discovery item list. The default value is true.
matches
With this option, the number of reported search results can be limited. If the option’s value is set to infinity, all search results are reported. The default value is 30.
ldap_vcard_map
With this option you can set the table that maps LDAP attributes to vCard fields. The format is: [Name_of_vCard_field, Pattern, List_of_LDAP_attributes, ...]. Name_of_vcard_field is the type name of the vCard as defined in RFC 2426. Pattern is a string which contains pattern variables "%u", "%d" or "%s". List_of_LDAP_attributes is the list containing LDAP attributes. The pattern variables "%s" will be sequentially replaced with the values of LDAP attributes from List_of_LDAP_attributes, "%u" will be replaced with the user part of a JID, and "%d" will be replaced with the domain part of a JID. The default is: 
[{"NICKNAME", "%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"]}]
ldap_search_fields
This option defines the search form and the LDAP attributes to search within. The format is: [Name, Attribute, ...]. Name is the name of a search form field which will be automatically translated by using the translation files (see msgs/*.msg for available words). Attribute is the LDAP attribute or the pattern "%u". The default is: 
[{"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"}]
ldap_search_reported
This option defines which search fields should be reported. The format is: [Name, vCard_Name, ...]. Name is the name of a search form field which will be automatically translated by using the translation files (see msgs/*.msg for available words). vCard_Name is the vCard field name defined in the ldap_vcard_map option. The default is: 
[{"Full Name", "FN"},
 {"Given Name", "FIRST"},
 {"Middle Name", "MIDDLE"},
 {"Family Name", "LAST"},
 {"Nickname", "NICKNAME"},
 {"Birthday", "BDAY"},
 {"Country", "CTRY"},
 {"City", "LOCALITY"},
 {"Email", "EMAIL"},
 {"Organization Name", "ORGNAME"},
 {"Organization Unit", "ORGUNIT"}]

Examples:

3.3.25  mod_version

This module implements Software Version (XEP-0092). Consequently, it answers ejabberd’s version when queried.

Options:

show_os
Should the operating system be revealed or not. The default value is true.
iqdisc
This specifies the processing discipline for Software Version (jabber:iq:version) IQ queries (see section 3.3.2).

Chapter 4  Managing an ejabberd Server

4.1  ejabberdctl

With the ejabberdctl command line administration script you can execute ejabberdctl commands (described in the next section, 4.1.1) and also many general ejabberd commands (described in section 4.2). This means you can start, stop and perform many other administrative tasks in a local or remote ejabberd server (by providing the argument --node NODENAME).

The ejabberdctl script can be configured in the file ejabberdctl.cfg. This file includes detailed information about each configurable option. See section 4.1.2.

The ejabberdctl script returns a numerical status code. Success is represented by 0, error is represented by 1, and other codes may be used for specific results. This can be used by other scripts to determine automatically if a command succeeded or failed, for example using: echo $?

4.1.1  ejabberdctl Commands

When ejabberdctl is executed without any parameter, it displays the available options. If there isn’t an ejabberd server running, the available parameters are:

start
Start ejabberd in background mode. This is the default method.
debug
Attach an Erlang shell to an already existing ejabberd server. This allows to execute commands interactively in the ejabberd server.
live
Start ejabberd in live mode: the shell keeps attached to the started server, showing log messages and allowing to execute interactive commands.

If there is an ejabberd server running in the system, ejabberdctl shows the ejabberdctl commands described bellow and all the ejabberd commands available in that server (see 4.2.1).

The ejabberdctl commands are:

help
Get help about ejabberdctl or any available command. Try ejabberdctl help help.
status
Check the status of the ejabberd server.
stop
Stop the ejabberd server.
restart
Restart the ejabberd server.
mnesia
Get information about the Mnesia database.

The ejabberdctl script can be restricted to require authentication and execute some ejabberd commands; see 4.2.2. Add the option to the file ejabberd.cfg. In this example there is no restriction: 

{ejabberdctl_access_commands, []}.

If account robot1@example.org is registered in ejabberd with password abcdef (which MD5 is E8B501798950FC58AAD83C8C14978E), and ejabberd.cfg contains this setting: 

{hosts, ["example.org"]}.
{acl, bots, {user, "robot1", "example.org"}}.
{access, ctlaccess, [{allow, bots}]}.
{ejabberdctl_access_commands, [ {ctlaccess, [registered_users, register], []} ]}.

then you can do this in the shell: 

$ ejabberdctl registered_users example.org
Error: no_auth_provided
$ ejabberdctl --auth robot1 example.org E8B501798950FC58AAD83C8C14978E registered_users example.org
robot1
testuser1
testuser2

4.1.2  Erlang Runtime System

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 ejabberdctl administration script uses many of those possibilities. You can configure some of them with the file 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:

EJABBERD_CONFIG_PATH
Path to the ejabberd configuration file.
EJABBERD_MSGS_PATH
Path to the directory with translated strings.
EJABBERD_LOG_PATH
Path to the ejabberd service log file.
EJABBERD_SO_PATH
Path to the directory with binary system libraries.
EJABBERD_DOC_PATH
Path to the directory with ejabberd documentation.
HOME
Path to the directory that is considered ejabberd’s home. This path is used to read the file .erlang.cookie.
ERL_CRASH_DUMP
Path to the file where crash reports will be dumped.
ERL_INETRC
Indicates which IP name resolution to use. If using -sname, specify either this option or -kernel inetrc filepath.
ERL_MAX_PORTS
Maximum number of simultaneously open Erlang ports.
ERL_MAX_ETS_TABLES
Maximum number of ETS and Mnesia tables.

The command line parameters:

-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.
-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.
-kernel inetrc "/etc/ejabberd/inetrc"
Indicates which IP name resolution to use. If using -sname, specify either this option or ERL_INETRC.
-kernel inet_dist_listen_min 4200 inet_dist_listen_min 4210
Define the first and last ports that epmd (section 5.2) can listen to.
-detached
Starts the Erlang system detached from the system console. Useful for running daemons and backgrounds processes.
-noinput
Ensures that the Erlang system never tries to read any input. Useful for running daemons and backgrounds processes.
-pa /var/lib/ejabberd/ebin
Specify the directory where Erlang binary files (*.beam) are located.
-s ejabberd
Tell Erlang runtime system to start the ejabberd application.
-mnesia dir "/var/lib/ejabberd/"
Specify the Mnesia database directory.
-sasl sasl_error_logger {file, "/var/log/ejabberd/sasl.log"}
Path to the Erlang/OTP system log file.
+K [true|false]
Kernel polling.
-smp [auto|enable|disable]
SMP support.
+P 250000
Maximum number of Erlang processes.
-remsh ejabberd@localhost
Open an Erlang shell in a remote Erlang node.
-hidden
The connections to other nodes are hidden (not published). The result is that this node is not considered part of the cluster. This is important when starting a temporary ctl or debug node.

Note that some characters need to be escaped when used in shell scripts, for instance " and {}. You can find other options in the Erlang manual page (erl -man erl).

4.2  ejabberd Commands

An ejabberd command is an abstract function identified by a name, with a defined number and type of calling arguments and type of result that is registered in the ejabberd_commands service. Those commands can be defined in any Erlang module and executed using any valid frontend.

ejabberd includes a frontend to execute ejabberd commands: the script ejabberdctl. Other known frontends that can be installed to execute ejabberd commands in different ways are: ejabberd_xmlrpc (XML-RPC service), mod_rest (HTTP POST service), mod_shcommands (ejabberd WebAdmin page).

4.2.1  List of ejabberd Commands

ejabberd includes a few ejabberd Commands by default. When more modules are installed, new commands may be available in the frontends.

The easiest way to get a list of the available commands, and get help for them is to use the ejabberdctl script: 

$ ejabberdctl help
Usage: ejabberdctl [--node nodename] [--auth user host password] command [options]

Available commands in this ejabberd node:
  backup file                  Store the database to backup file
  connected_users              List all established sessions
  connected_users_number       Get the number of established sessions
  delete_expired_messages      Delete expired offline messages from database
  delete_old_messages days     Delete offline messages older than DAYS
  ...

The more interesting ones are:

reopen-log
Reopen the log files after they were renamed. If the old files were not renamed before calling this command, they are automatically renamed to "*-old.log". See section 7.1.
backup ejabberd.backup
Store internal Mnesia database to a binary backup file.
restore ejabberd.backup
Restore immediately from a binary backup file the internal Mnesia database. This will consume quite some memory for big servers.
install-fallback ejabberd.backup
The binary backup file is installed as fallback: it will be used to restore the database at the next ejabberd start. Similar to restore, but requires less memory.
dump ejabberd.dump
Dump internal Mnesia database to a text file dump.
load ejabberd.dump
Restore immediately from a text file dump. This is not recommended for big databases, as it will consume much time, memory and processor. In that case it’s preferable to use backup and install-fallback.
import-file, import-dir
These options can be used to migrate from other Jabber/XMPP servers. There exist tutorials to migrate from other software to ejabberd.
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.

4.2.2  Restrict Execution with AccessCommands

The frontends can be configured to restrict access to certain commands. In that case, authentication information must be provided. In each frontend the AccessCommands option is defined in a different place. But in all cases the option syntax is the same: 

AccessCommands = [ {Access, CommandNames, Arguments} ]
Access = atom()
CommandNames = all | [CommandName]
CommandName = atom()
Arguments = [{ArgumentName, ArgumentValue}]
ArgumentName = atom()
ArgumentValue = any()

The default value is to not define any restriction: []. If at least one restriction is defined, then the frontend expects that authentication information is provided when executing a command. The authentication information is Username, Hostname and Password of a local Jabber account that has permission to execute the corresponding command. This means that the account must be registered in the local ejabberd, because the information will be verified. It is possible to provide the plaintext password or its MD5 sum.

When one or several access restrictions are defined and the authentication information is provided, each restriction is verified until one matches completely: the account matches the Access rule, the command name is listed in CommandNames, and the provided arguments do not contradict Arguments.

As an example to understand the syntax, let’s suppose those options: 

{hosts, ["example.org"]}.
{acl, bots, {user, "robot1", "example.org"}}.
{access, commaccess, [{allow, bots}]}.

This list of access restrictions allows only robot1@example.org to execute all commands: 

[{commaccess, all, []}]

See another list of restrictions (the corresponding ACL and ACCESS are not shown): 

[
 %% This bot can execute all commands:
 {bot, all, []},
 %% This bot can only execute the command 'dump'. No argument restriction:
 {bot_backups, [dump], []}
 %% This bot can execute all commands,
 %% but if a 'host' argument is provided, it must be "example.org":
 {bot_all_example, all, [{host, "example.org"}]},
 %% This bot can only execute the command 'register',
 %% and if argument 'host' is provided, it must be "example.org":
 {bot_reg_example, [register], [{host, "example.org"}]},
 %% This bot can execute the commands 'register' and 'unregister',
 %% if argument host is provided, it must be "test.org":
 {_bot_reg_test, [register, unregister], [{host, "test.org"}]}
]

4.3  Web Admin

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

This feature is enabled by default: a ejabberd_http listener with the option web_admin (see section 3.1.3) is included in the listening ports. Then you can open http://server:port/admin/ in your favourite web browser. You will be asked to enter the username (the full Jabber ID) and password of an ejabberd user with administrator rights. After authentication you will see a page similar to figure 4.1.

webadmmain.png
Figure 4.1: Top page from the Web Admin

Here you can edit access restrictions, manage users, create backups, manage the database, enable/disable ports listened for, view server statistics,…

Examples:

Certain pages in the ejabberd Web Admin contain a link to a related section in the ejabberd Installation and Operation Guide. In order to view such links, a copy in HTML format of the Guide must be installed in the system. The file is searched by default in "/share/doc/ejabberd/guide.html". The directory of the documentation can be specified in the environment variable EJABBERD_DOC_PATH. See section 4.1.2.

4.4  Ad-hoc Commands

If you enable mod_configure and mod_adhoc, you can perform several administrative tasks in ejabberd with a Jabber client. The client must support Ad-Hoc Commands (XEP-0050), and you must login in the Jabber server with an account with proper privileges.

4.5  Change Computer Hostname

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 (see section 5.4). 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.

You have two ways to use the old Mnesia database in an ejabberd with new node name: put the old node name in ejabberdctl.cfg, or convert the database to the new node name.

Those example steps will backup, convert and load the Mnesia database. You need to have either the old Mnesia spool dir or a backup of Mnesia. If you already have a backup file of the old database, you can go directly to step 5. You also need to know the old node name and the new node name. If you don’t know them, look for them by executing ejabberdctl or in the ejabberd log files.

Before starting, setup some variables: 

OLDNODE=ejabberd@oldmachine
NEWNODE=ejabberd@newmachine
OLDFILE=/tmp/old.backup
NEWFILE=/tmp/new.backup
  1. Start ejabberd enforcing the old node name: 
    ejabberdctl --node $OLDNODE start
  2. Generate a backup file: 
    ejabberdctl --node $OLDNODE backup $OLDFILE
  3. Stop the old node: 
    ejabberdctl --node $OLDNODE stop
  4. Make sure there aren’t files in the Mnesia spool dir. For example: 
    mkdir /var/lib/ejabberd/oldfiles
mv /var/lib/ejabberd/*.* /var/lib/ejabberd/oldfiles/
  5. Start ejabberd. There isn’t any need to specify the node name anymore: 
    ejabberdctl start
  6. Convert the backup to new node name: 
    ejabberdctl mnesia_change_nodename $OLDNODE $NEWNODE $OLDFILE $NEWFILE
  7. Import the new backup: 
    ejabberdctl restore $NEWFILE
  8. Check that the information of the old database is available: accounts, rosters... After you finish, remember to delete the temporary backup files from public directories.

Chapter 5  Securing ejabberd

5.1  Firewall Settings

You need to take the following TCP ports in mind when configuring your firewall:

PortDescription
5222Standard port for Jabber/XMPP client connections, plain or STARTTLS.
5223Standard port for Jabber client connections using the old SSL method.
5269Standard port for Jabber/XMPP server connections.
4369EPMD (section 5.2) listens for Erlang node name requests.
port rangeUsed for connections between Erlang nodes. This range is configurable (see section 5.2).

5.2  epmd

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 epmd to use 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 epmd if you want.

ejabberd runs inside an Erlang node. To communicate with ejabberd, the script ejabberdctl starts a new Erlang node and connects to the Erlang node that holds ejabberd. In order for this communication to work, epmd must be running and listening for name requests in the port 4369. You should block the port 4369 in the firewall in such a way that 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 by default are random, but can be configured in the file ejabberdctl.cfg. The Erlang command-line parameter used internally is, for example: 

erl ... -kernel inet_dist_listen_min 4370 inet_dist_listen_max 4375

5.3  Erlang Cookie

The Erlang cookie is a string with numbers and letters. An Erlang node reads the cookie at startup from the command-line parameter -setcookie. If not indicated, the cookie is read from the cookie file $HOME/.erlang.cookie. If this file does not exist, it is created immediately with a random cookie. 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.

5.4  Erlang Node Name

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

Using the option -sname instead of -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 epmd. The recommended way to secure the Erlang node is to block the port 4369.

5.5  Securing Sensible Files

ejabberd stores sensible data in the file system either in plain text or binary files. The file system permissions should be set to only allow the proper user to read, write and execute those files and directories.

ejabberd configuration file: /etc/ejabberd/ejabberd.cfg
Contains the JID of administrators and passwords of external components. The backup files probably contain also this information, so it is preferable to secure the whole /etc/ejabberd/ directory.
ejabberd service log: /var/log/ejabberd/ejabberd.log
Contains IP addresses of clients. If the loglevel is set to 5, it contains whole conversations and passwords. If a logrotate system is used, there may be several log files with similar information, so it is preferable to secure the whole /var/log/ejabberd/ directory.
Mnesia database spool files in /var/lib/ejabberd/
The files store binary data, but some parts are still readable. The files are generated by Mnesia and their permissions cannot be set directly, so it is preferable to secure the whole /var/lib/ejabberd/ directory.
Erlang cookie file: /var/lib/ejabberd/.erlang.cookie
See section 5.3.

Chapter 6  Clustering

6.1  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 ~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…

Each ejabberd node has the following modules:

6.1.1  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.

6.1.2  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.

6.1.3  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.

6.1.4  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.

6.2  Clustering Setup

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

  1. Copy ~ejabberd/.erlang.cookie file from first to second.

    (alt) You can also add ‘-cookie content_of_.erlang.cookie’ option to all ‘erl’ commands below.

  2. On second run the following command as the ejabberd daemon user, in the working directory of ejabberd:
    erl -sname ejabberd \
    -mnesia dir "/var/lib/ejabberd/" \
    -mnesia extra_db_nodes "['ejabberd@first']" \
    -s mnesia

    This will start Mnesia serving the same database as ejabberd@first. You can check this by running the command ‘mnesia:info().’. You should see a lot of remote tables and a line like the following:

    Note: the Mnesia directory may be different in your system. To know where does ejabberd expect Mnesia to be installed by default, call 4.1 without options and it will show some help, including the Mnesia database spool dir.

    running db nodes   = [ejabberd@first, ejabberd@second]
  3. Now run the following in the same ‘erl’ session:
    mnesia:change_table_copy_type(schema, node(), disc_copies).

    This will create local disc storage for the database.

    (alt) Change storage type of the scheme table to ‘RAM and disc copy’ on the second node via the Web Admin.

  4. Now you can add replicas of various tables to this node with ‘mnesia:add_table_copy’ or ‘mnesia:change_table_copy_type’ as above (just replace ‘schema’ with another table name and ‘disc_copies’ can be replaced with ‘ram_copies’ or ‘disc_only_copies’).

    Which tables to replicate is very dependant on your needs, you can get some hints from the command ‘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 section 5.3 (Table Fragmentation) of Mnesia User’s Guide can be helpful.

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

  5. Run ‘init:stop().’ or just ‘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 first.
  6. Now run ejabberd on second with a configuration similar as on first: you probably do not need to duplicate ‘acl’ and ‘access’ options because they will be taken from first; and mod_irc should be enabled only on one machine in the cluster.

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

6.3  Service Load-Balancing

6.3.1  Components Load-Balancing

6.3.2  Domain Load-Balancing Algorithm

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 domain_balancing. The syntax of the option is the following:

{domain_balancing, "component.example.com", <balancing_criterium>}.

Several balancing criteria are available:

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

6.3.3  Load-Balancing Buckets

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 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: 

{domain_balancing_component_number, "component.example.com", N}

Chapter 7  Debugging

7.1  Log Files

An ejabberd node writes two log files:

ejabberd.log
is the ejabberd service log, with the messages reported by ejabberd code
sasl.log
is the Erlang/OTP system log, with the messages reported by Erlang/OTP using SASL (System Architecture Support Libraries)

The option loglevel modifies the verbosity of the file ejabberd.log. The possible levels are:

0
No ejabberd log at all (not recommended)
1
Critical
2
Error
3
Warning
4
Info
5
Debug

For example, the default configuration is: 

{loglevel, 4}.

The log files grow continually, so it is recommended to rotate them periodically. To rotate the log files, rename the files and then reopen them. The ejabberdctl command reopen-log (please refer to section 4.1.1) reopens the log files, and also renames the old ones if you didn’t rename them.

7.2  Debug Console

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 Interconnecting Erlang Nodes

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

7.3  Watchdog Alerts

ejabberd includes a watchdog mechanism that may be useful to developers when troubleshooting a problem related to memory usage. If a process in the ejabberd server consumes more memory than the configured threshold, a message is sent to the Jabber accounts defined with the option watchdog_admins in the ejabberd configuration file.

The memory consumed is measured in words: a word on 32-bit architecture is 4 bytes, and a word on 64-bit architecture is 8 bytes. The threshold by default is 1000000 words. This value can be configured with the option watchdog_large_heap, or in a conversation with the watchdog alert bot.

Example configuration: 

{watchdog_admins, ["admin2@localhost", "admin2@example.org"]}.
{watchdog_large_heap, 30000000}.

To remove watchdog admins, remove them in the option. To remove all watchdog admins, set the option with an empty list: 

{watchdog_admins, []}.

Appendix A  Internationalization and Localization

The source code of ejabberd supports localization. The translators can edit the gettext .po files using any capable program (KBabel, Lokalize, Poedit...) or a simple text editor.

Then gettext is used to extract, update and export those .po files to the .msg format read by ejabberd. To perform those management tasks, in the src/ directory execute make translations. The translatable strings are extracted from source code to generate the file ejabberd.pot. This file is merged with each .po file to produce updated .po files. Finally those .po files are exported to .msg files, that have a format easily readable by ejabberd.

All built-in modules support the xml:lang attribute inside IQ queries. Figure A.1, for example, shows the reply to the following query: 

<iq id='5'
    to='example.org'
    type='get'
    xml:lang='ru'>
  <query xmlns='http://jabber.org/protocol/disco#items'/>
</iq>
discorus.png
Figure A.1: Service Discovery when xml:lang=’ru’

The Web Admin also supports the Accept-Language HTTP header.

webadmmainru.png
Figure A.2: Web Admin showing a virtual host when the web browser provides the HTTP header ‘Accept-Language: ru’

Appendix B  Release Notes

Release notes are available from ejabberd Home Page

Appendix C  Acknowledgements

Thanks to all people who contributed to this guide:

Appendix D  Copyright Information

Ejabberd Installation and Operation Guide.
Copyright © 2003 — 2009 ProcessOne

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.

This document was translated from LATEX by HEVEA.