Ejabberd 1.1.2 Installation and Operation Guide

Alexey Shchepin
mailto:alexey@sevcom.net
xmpp:aleksey@jabber.ru


logo.png

I can thoroughly recommend ejabberd for ease of setup — Kevin Smith, Current maintainer of the Psi project

Contents

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:

2  Installation from Source

2.1  Installation Requirements

2.1.1  `Unix-like' operating systems

To compile ejabberd on a `Unix-like' operating system, you need:

2.1.2  Windows

To compile ejabberd on a Windows flavour, you need:

2.2  Obtaining ejabberd

Released versions of ejabberd can be obtained from
http://www.process-one.net/en/projects/ejabberd/download.html.

The latest development version can be retrieved from the Subversion repository. 
  svn co http://svn.process-one.net/ejabberd/trunk ejabberd

2.3  Compilation

2.3.1  `Unix-like' operating systems

Compile ejabberd on a `Unix-like' operating system by executing: 
  ./configure
  make
  su
  make install
These commands will: Note: if you want to use an external database, you need to execute the configure script with the option(s) –enable-odbc or –enable-odbc –enable-mssql. See section 4 for more information.

2.3.2  Windows

2.4  Starting

Execute the following command to start ejabberd: 
  erl -pa /var/lib/ejabberd/ebin -name ejabberd -s ejabberd
or 
  erl -pa /var/lib/ejabberd/ebin -sname ejabberd -s ejabberd
In the latter case 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.

Note that when using the above command, ejabberd will search for the configuration file in the current directory and will use the current directory for storing its user database and for logging.

To specify the path to the configuration file, the log files and the Mnesia database directory, you may use the following command: 
  erl -pa /var/lib/ejabberd/ebin \
      -sname ejabberd \
      -s ejabberd \
      -ejabberd config \"/etc/ejabberd/ejabberd.cfg\" \
                log_path \"/var/log/ejabberd/ejabberd.log\" \
      -sasl sasl_error_logger \{file,\"/var/log/ejabberd/sasl.log\"\} \
      -mnesia dir \"/var/lib/ejabberd/spool\"
You can find other useful options in the Erlang manual page (erl -man erl).

To use more than 1024 connections, you should set the environment variable ERL_MAX_PORTS: 
  export ERL_MAX_PORTS=32000
Note that with this value, ejabberd will use more memory (approximately 6 MB more).

To reduce memory usage, you may set the environment variable ERL_FULLSWEEP_AFTER: 
  export ERL_FULLSWEEP_AFTER=0
But in this case ejabberd can start to work slower.

3  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 a 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. 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, local options and ACLs will be removed before new ones are added.

3.1  Host Names

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

Examples:

3.2  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:

3.3  Listened Sockets

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: Currently next modules are implemented:
ejabberd_c2s Description Handles c2s connections.
  Options access, certfile, inet6, ip, max_stanza_size, shaper, ssl, tls, starttls, starttls_required, zlib
ejabberd_s2s_in Description Handles incoming s2s connections.
  Options inet6, ip, max_stanza_size
ejabberd_service Description Interacts with external components (*).
  Options access, hosts, inet6, ip, shaper
ejabberd_http Description Handles incoming HTTP connections.
  Options certfile, http_poll, inet6, ip, tls, web_admin
(*) The mechanism for external components is defined in Jabber Component Protocol (JEP-0114).

The following options are available:
{access, <access rule>}
This option defines access to the port. The default value is all.
{certfile, Path}
Path to a file containing the SSL certificate.
{hosts, [Hostnames], [HostOptions]}
This option defines one or more hostnames of connected services and enables you to specify additional options including {password, Secret}.
http_poll
This option enables HTTP Polling (JEP-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 (there is a tutorial to install JWChat with instructions for ejabberd).
inet6
Set up the socket for IPv6.
{ip, IPAddress}
This option specifies which network interface to listen for. For example {ip, {192, 168, 1, 1}}.
{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.
{shaper, <access rule>}
This option defines a shaper for the port (see section 3.6). The default value is none.
ssl
This option specifies that traffic on the port will be encrypted using SSL. You should also set the certfile option. It is recommended to use the tls option instead.
starttls
This option specifies that STARTTLS encryption is available on connections to the port. You should also set the certfile option.
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.
tls
This option specifies that traffic on the port will be encrypted using SSL immediately after connecting. You should also set the certfile option.
zlib
This option specifies that Zlib stream compression (as defined in JEP-0138) is available on connections to the port. Client connections cannot use stream compression and stream encryption simultaneously. Hence, if you specify both tls (or ssl) and zlib, the latter option will not affect connections (there will be no stream compression).
web_admin
This option enables the web interface 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.
In addition, the following options are available for s2s connections:
{s2s_use_starttls, true|false}
This option defines whether to use STARTTLS for s2s connections.
{s2s_certfile, Path}
Path to a file containing a SSL certificate.
{domain_certfile, Domain, Path}
Path to the file containing the SSL certificate for the specified domain.
For instance, 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, ejabberd_c2s,     [{access, c2s},
                              ssl, {certfile, "/path/to/ssl.pem"}]},
    {5269, ejabberd_s2s_in,  []},
    {5280, ejabberd_http,    [http_poll, web_admin]},
    {5233, ejabberd_service, [{host, "aim.example.org",
                               [{password, "aimsecret"}]}]},
    {5234, ejabberd_service, [{hosts, ["icq.example.org", "sms.example.org"],
                               [{password, "jitsecret"}]}]},
    {5235, ejabberd_service, [{host, "msn.example.org",
                               [{password, "msnsecret"}]}]},
    {5236, ejabberd_service, [{host, "yahoo.example.org",
                               [{password, "yahoosecret"}]}]},
    {5237, ejabberd_service, [{host, "gg.example.org",
                               [{password, "ggsecret"}]}]},
    {5238, ejabberd_service, [{host, "jmc.example.org",
                               [{password, "jmcsecret"}]}]}
   ]
  }.
  {s2s_use_starttls, true}.
  {s2s_certfile, "/path/to/ssl.pem"}.
Note, that for jabberd 1.4- or WPJabber-based services 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 jabberd -->
      <xdb_file>/usr/lib/jabber/xdb_file.so</xdb_file>
      </load>
    <xdb_file xmlns="jabber:config:xdb_file">
      <spool><jabberd:cmdline flag='s'>/var/spool/jabber</jabberd:cmdline></spool>
    </xdb_file>
  </xdb>

3.4  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:

3.4.1  Internal

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

3.4.2  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 3.2). 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 3.2).

Examples:

3.5  Access Rules

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"}}.
{user_regexp, <regexp>}
Matches any local user with a name that matches <regexp> at the first virtual host. Example: 
{acl, tests, {user, "^test[0-9]*$"}}.
{user_regexp, <regexp>, <server>}
Matches any user with a name that matches <regexp> at server <server>. Example: 
{acl, tests, {user, "^test", "example.org"}}.
{server_regexp, <regexp>}
Matches any JID from the server that matches <regexp>. Example: 
{acl, icq, {server, "^icq\\."}}.
{node_regexp, <user_regexp>, <server_regexp>}
Matches any user with a name that matches <user_regexp> at any server that matches <server_regexp>. Example: 
{acl, yohzik, {node_regexp, "^yohzik$", "^example.(com|org)$"}}.
{user_glob, <glob>}
{user_glob, <glob>, <server>}
{server_glob, <glob>}
{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.
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 mathes 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'.

3.6  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 incomig rate in bytes per second.

Examples:

3.7  Limiting Opened Sessions

This option 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 10.

Examples:

3.8  Default Language

The option language defines the default language of server strings that can be seen by Jabber clients. If a Jabber client do 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.

Examples:

4  Database Configuration

ejabberd uses its internal Mnesia database by default. However, it is possible to use a relational database or an LDAP server to store persistant, 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:

4.1  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.

4.1.1  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

4.1.2  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: 
{host_config, "public.example.org", [{auth_method, [odbc]}]}.
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"}}.

4.1.3  Storage

MySQL also can be used to store information into from several ejabberd modules. See section 5.1 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!

4.2  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.

4.2.1  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

4.2.2  Authentication

The configuration of Microsoft SQL Server is the same as the configuration of ODBC compatible serers (see section 4.4.2).

4.2.3  Storage

Microsoft SQL Server also can be used to store information into from several ejabberd modules. See section 5.1 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!

4.3  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.

4.3.1  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 Jungerl. 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

4.3.2  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: 
{host_config, "public.example.org", [{auth_method, [odbc]}]}.
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"}}.

4.3.3  Storage

PostgreSQL also can be used to store information into from several ejabberd modules. See section 5.1 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!

4.4  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.

4.4.1  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

4.4.2  Authentication

The first configuration step is to define the odbc auth_method. For example: 
{host_config, "public.example.org", [{auth_method, [odbc]}]}.
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"}.

4.4.3  Storage

An ODBC compatible database also can be used to store information into from several ejabberd modules. See section 5.1 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!

4.5  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.

4.5.1  Connection

Parameters:
ldap_server
IP address or dns name of your LDAP server. This option is required.
ldap_port
Port to connect to your LDAP server. The default value is 389.
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.

4.5.2  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.

4.5.3  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. 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"}.
  %% 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 showed 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=*)"}.
  
  {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"}]}
   ]
  }.

5  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:

5.1  Overview

The following table lists all modules available in the official ejabberd distribution. 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!

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:
Module Feature Dependencies Needed for XMPP?
mod_adhoc Ad-Hoc Commands (JEP-0050)   No
mod_announce Manage announcements mod_adhoc No
mod_configure Support for online mod_adhoc No
  configuration of ejabberd    
mod_disco Service Discovery (JEP-0030)   No
mod_echo Echoes Jabber packets   No
mod_irc IRC transport   No
mod_last Last Activity (JEP-0012)   No
mod_last_odbc Last Activity (JEP-0012) supported database (*) No
mod_muc Multi-User Chat (JEP-0045)   No
mod_muc_log Multi-User Chat room logging mod_muc No
mod_offline Offline message storage   No
mod_offline_odbc Offline message storage supported database (*) No
mod_privacy Blocking Communication   Yes
mod_private Private XML Storage (JEP-0049)   No
mod_proxy65 SOCKS5 Bytestreams (JEP-0065)   No
mod_pubsub Publish-Subscribe (JEP-0060)   No
mod_register In-Band Registration (JEP-0077)   No
mod_roster Roster management   Yes (**)
mod_roster_odbc Roster management supported database (*) Yes (**)
mod_service_log Copy user messages to logger service   No
mod_shared_roster Shared roster management mod_roster or No
    mod_roster_odbc  
mod_stats Statistics Gathering (JEP-0039)   No
mod_time Entity Time (JEP-0090)   No
mod_vcard vcard-temp (JEP-0054)   No
mod_vcard_ldap vcard-temp (JEP-0054) LDAP server No
mod_vcard_odbc vcard-temp (JEP-0054) supported database (*) No
mod_version Software Version (JEP-0092)   No

5.2  Common Options

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

5.2.1  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.
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}]},
    ...
   ]}.

5.2.2  hosts

A module acting as a service can have one or more hostnames. These hostnames can be defined with the hosts option.

Examples:

5.3  mod_announce

This module enables configured users to broadcast announcements and to set the message of the day (MOTD). Configured users can do these actions with their Jabber client by sending messages to specific JIDs. These JIDs are listed in next paragraph. The first JID in each entry will apply only to the virtual host example.org, while the JID between brackets will apply to all virtual hosts:
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 5.10) 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:

5.4  mod_disco

This module adds support for Service Discovery (JEP-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 (JEP-0011) and Agent Information (JEP-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 5.2.1).
extra_domains
With this option, extra domains can be added to the Service Discovery item list.
Examples:

5.5  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:
hosts
This option defines the hostnames of the service (see section 5.2.2). If neither hosts nor the old host is present, the prefix `echo.' is added to all ejabberd hostnames.
Examples:

5.6  mod_irc

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

End user information: Options:
hosts
This option defines the hostnames of the service (see section 5.2.2). If neither hosts nor the old host is present, the prefix `irc.' is added to all ejabberd hostnames.
access
This option can be used to specify who may use the IRC transport (default value: all).
Examples:

5.7  mod_last

This module adds support for Last Activity (JEP-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 5.2.1).

5.8  mod_muc

With this module enabled, your server will support Multi-User Chat (JEP-0045). End users will be able to join text conferences. Notice that this module is not (yet) clusterable.

Some of the features of Multi-User Chat: Options:
hosts
This option defines the hostnames of the service (see section 5.2.2). If neither hosts nor the old host is present, the prefix `conference.' is added to all ejabberd hostnames.
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_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). By sending a message to the service JID, administrators can send service messages that will be displayed in every active room.
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 server.
Examples:

5.9  mod_muc_log

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

Features: Options:
access_log
This option restricts which users are allowed to enable or disable chatroom 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.
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.
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".
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:

5.10  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 7.2).

5.11  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 5.2.1).

5.12  mod_private

This module adds support for Private XML Storage (JEP-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 (JEP-0048).
Options:
iqdisc
This specifies the processing discipline for Private XML Storage (jabber:iq:private) IQ queries (see section 5.2.1).

5.13  mod_proxy65

This module implements SOCKS5 Bytestreams (JEP-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:

5.14  mod_pubsub

This module offers a Publish-Subscribe Service (JEP-0060). Publish-Subscribe can be used to develop (examples are taken from the JEP):
Another example is J-EAI. This is an XMPP-based Enterprise Application Integration (EAI) platform (also known as ESB, the Enterprise Service Bus). The J-EAI project builts upon ejabberd's codebase and has contributed several features to mod_pubsub.

Options:
hosts
This option defines the hostnames of the service (see section 5.2.2). If neither hosts nor the old host is present, the prefix `pubsub.' is added to all ejabberd hostnames.
served_hosts
To specify which hosts needs to be served, you can use this option. If absent, only the main ejabberd host is served.
access_createnode
This option restricts which users are allowed to create pubsub nodes using ACL and ACCESS. The default value is pubsub_createnode.
Example: 
  {modules,
   [
    ...
    {mod_pubsub, [{served_hosts, ["example.com",
                                  "example.org"]},
                  {access_createnode, pubsub_createnode}]}
    ...
   ]}.

5.15  mod_register

This module adds support for In-Band Registration (JEP-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 dennied. (there are no restrictions by default).
iqdisc
This specifies the processing discipline for In-Band Registration (jabber:iq:register) IQ queries (see section 5.2.1).
Examples:

5.16  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 5.2.1).

5.17  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:

5.18  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.

Shared roster groups can be edited only via the web interface. 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 interface.
Displayed groups
A list of groups that will be in the rosters of this group's members.
Examples:

5.19  mod_stats

This module adds support for Statistics Gathering (JEP-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 5.2.1).
As there are only a small amount of clients (for example Tkabber) and software libraries with support for this JEP, a few examples are given of the XML you need to send in order to get the statistics. Here they are:

5.20  mod_time

This module features support for Entity Time (JEP-0090). By using this JEP, 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 5.2.1).

5.21  mod_vcard

This module allows end users to store and retrieve their vCard, and to retrieve other users vCards, as defined in vcard-temp (JEP-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:
hosts
This option defines the hostnames of the service (see section 5.2.2). If neither hosts nor the old host is present, the prefix `vjud.' is added to all ejabberd hostnames.
iqdisc
This specifies the processing discipline for vcard-temp IQ queries (see section 5.2.1).
search
This option specifies whether the search functionality is enabled (value: true) or disabled (value: false). If disabled, the option hosts 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.
Examples:

5.22  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 4.5.2). 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 4.5.2 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:
hosts
This option defines the hostnames of the service (see section 5.2.2). If neither hosts nor the old host is present, the prefix `vjud.' is added to all ejabberd hostnames.
iqdisc
This specifies the processing discipline for vcard-temp IQ queries (see section 5.2.1).
search
This option specifies whether the search functionality is enabled (value: true) or disabled (value: false). If disabled, the option hosts will be ignored and the Jabber User Directory service will not appear in the Service Discovery item list. The default value is true.
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"]},
   {"FAMILY", "%s", ["sn"]},
   {"GIVEN", "%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", "GIVEN"},
   {"Middle Name", "MIDDLE"},
   {"Family Name", "FAMILY"},
   {"Nickname", "NICKNAME"},
   {"Birthday", "BDAY"},
   {"Country", "CTRY"},
   {"City", "LOCALITY"},
   {"Email", "EMAIL"},
   {"Organization Name", "ORGNAME"},
   {"Organization Unit", "ORGUNIT"}]
Examples:

5.23  mod_version

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

Options:
iqdisc
This specifies the processing discipline for Software Version (jabber:iq:version) IQ queries (see section 5.2.1).

6  Creating an Initial Administrator

Before the web interface can be entered to perform administration tasks, an account with administrator rights is needed on your ejabberd deployment.

Instructions to create an initial administrator account:
  1. Register an account on your ejabberd deployment. An account can be created in two ways:
    1. Using the tool ejabberdctl (see section 7.2): 
      % ejabberdctl node@host register admin example.org password
    2. Using In-Band Registration (see section 5.15): you can use a Jabber client to register an account.
  2. Edit the configuration file to promote the account created in the previous step to an account with administrator rights. Note that if you want to add more administrators, a seperate acl entry is needed for each administrator. 
      {acl, admins, {user, "admin", "example.org"}}.
  {access, configure, [{allow, admins}]}.
  3. Restart ejabberd to load the new configuration.
  4. Open the web interface (http://server:port/admin/) in your favourite browser. Make sure to enter the full JID as username (in this example: admin@example.org. The reason that you also need to enter the suffix, is because ejabberd's virtual hosting support.

7  Online Configuration and Monitoring

7.1  Web Interface

To perform online configuration of ejabberd you need to enable the ejabberd_http listener with the option web_admin (see section 3.3). 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 1.
webadmmain.png

Figure 1: Top page from the web interface


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

Examples:

7.2  ejabberdctl

It is possible to do some administration operations using the command line tool ejabberdctl. You can list all available options by running ejabberdctl without arguments: 
% ejabberdctl
Usage: ejabberdctl node command

Available commands:
  status                        get ejabberd status
  stop                          stop ejabberd
  restart                       restart ejabberd
  reopen-log                    reopen log file
  register user server password register a user
  unregister user server        unregister a user
  backup file                   store a database backup to file
  restore file                  restore a database backup from file
  install-fallback file         install a database fallback from file
  dump file                     dump a database to a text file
  load file                     restore a database from a text file
  import-file file              import user data from jabberd 1.4 spool file
  import-dir dir                import user data from jabberd 1.4 spool directory
  registered-users              list all registered users
  delete-expired-messages       delete expired offline messages from database

Example:
  ejabberdctl ejabberd@host restart
Additional information:
reopen-log
If you use a tool to rotate logs, you have to configure it so that this command is executed after each rotation.
backup, restore, install-fallback, dump, load
You can use these commands to create and restore backups.
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.

8  Firewall Settings

You need to take the following TCP ports in mind when configuring your firewall:
Port Description
5222 SASL and unencrypted c2s connections.
5223 Obsolete SSL c2s connections.
5269 s2s connections.
4369 Only for clustering (see 10).
port range Only for clustring (see 10). This range is configurable (see 2.4).

9  SRV Records

10  Clustering

10.1  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:

10.1.1  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.

10.1.2  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.

10.1.3  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.

10.1.4  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.

10.2  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 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: 
    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 interface.

  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 almost the same config as on first (you probably do not need to duplicate `acl' and `access' options — they will be taken from first, and mod_muc 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.

A  Internationalization and Localization

All built-in modules support the xml:lang attribute inside IQ queries. Figure 2, 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 2: Service Discovery when xml:lang='ru'


The web interface also supports the Accept-Language HTTP header (compare figure 3 with figure 1)
webadmmainru.png

Figure 3: Top page from the web interface with HTTP header `Accept-Language: ru'


B  Release Notes

B.1  ejabberd 0.9

       Release notes
        ejabberd 0.9

    This document describes the major new features of and changes to
    ejabberd 0.9, compared to latest public release ejabber 0.7.5.

    For more detailed information, please refer to ejabberd User
    Guide.


Virtual Hosting

    ejabberd now can host several domain on the same instance.
    This option is enabled by using:

      {hosts, ["erlang-projects.org", "erlang-fr.org"]}.

    instead of the previous host directive.

    Note that you are now using a list of hosts. The main one should
    be the first listed. See migration section further in this release
    note for details.
      

Shared Roster

    Shared roster is a new feature that allow the ejabberd
    administrator to add jabber user that will be present in the
    roster of every users on the server.
    Shared roster are enabled by adding:

            {mod_shared_roster, []}

    at the end of your module list in your ejabberd.cfg file.


PostgreSQL (ODBC) support

    This feature is experimental and not yet properly documented. This
    feature is released for testing purpose.

    You need to have Erlang/OTP R10 to compile with ODBC on various
    flavour of *nix. You should use Erlang/OTP R10B-4, as this task
    has became easier with this release. It comes already build in
    Erlang/OTP Microsoft Windows binary.

    PostgreSQL support is enabled by using the following module in
    ejabberd.cfg instead of their standard counterpart:

     mod_last_odbc.erl
     mod_offline_odbc.erl
     mod_roster_odbc.erl

    The database schema is located in the src/odbc/pq.sql file.

    Look at the src/ejabberd.cfg.example file for more information on
    how to configure ejabberd with odbc support. You can get support
    on how to configure ejabberd with a relational database.


Migration from ejabberd 0.7.5

    Migration is pretty straightforward as Mnesia database schema
    conversions is handled automatically. Remember however that you
    must backup your ejabberd database before migration.

    Here are the following steps to proceed:

    1. Stop your instance of ejabberd.

    2. In ejabberd.cfg, define the host lists. Change the host
    directive to the hosts one:
    Before:
      {host, "erlang-projects.org"}.
    After:
      {hosts, ["erlang-projects.org", "erlang-fr.org"]}.
    Note that when you restart the server the existing users will be
    affected to the first virtual host, so the order is important. You
    should keep the previous hostname as the first virtual host.

    3. Restart ejabberd.


Bugfixes

    This release contains several bugfixes and architectural changes.
    Please refer to the Changelog file supplied with this release for
    details of all improvements in the ejabberd code.

B.2  ejabberd 0.9.1

       Release notes
       ejabberd 0.9.1

   This document describes the main changes from [25]ejabberd 0.9.

   The code can be downloaded from the [26]download page.

   For more detailed information, please refer to ejabberd [27]User Guide.


Groupchat (Multi-user chat and IRC) improvements

   The multi-user chat code has been improved to comply with the latest version
   of Jabber Enhancement Proposal 0045.

   The IRC (Internet Relay Chat) features now support WHOIS and USERINFO
   requests.


Web interface

   ejabberd modules management features have been added to the web interface.
   They now allow to start or stop extension module without restarting the
   ejabberd server.


Publish and subscribe

   It is now possible to a subscribe node with a JabberID that includes a
   resource.


Translations

   A new script has been included to help translate ejabberd into new languages
   and maintain existing translations.

   As a result, ejabberd is now translating into 10 languages:
     * Dutch
     * English
     * French
     * German
     * Polish
     * Portuguese
     * Russian
     * Spanish
     * Swedish
     * Ukrainian


Migration

   No changes have been made to the database. No particular conversion steps
   are needed. However, you should backup your database before upgrading to a
   new ejabberd version.


Bugfixes

   This release contains several bugfixes and architectural changes. Please
   refer to the Changelog file supplied with this release for details of all
   improvements in the ejabberd code.

B.3  ejabberd 0.9.8

       Release notes
       ejabberd 0.9.8
         2005-08-01

   This document describes the main changes in ejabberd 0.9.8. This
   version prepares the way for the release of ejabberd 1.0, which 
   is due later this year.

   The code can be downloaded from the Process-one website:
   http://www.process-one.net/en/projects/ejabberd/

   For more detailed information, please refer to ejabberd User Guide
   on the Process-one website:
   http://www.process-one.net/en/projects/ejabberd/docs.html


   Recent changes include....


Enhanced virtual hosting

   Virtual hosting applies to many more setting options and
   features and is transparent. Virtual hosting accepts different
   parameters for different virtual hosts regarding the following
   features: authentication method, access control lists and access
   rules, users management, statistics, and shared roster. The web
   interface gives access to each virtual host's parameters.


Enhanced Publish-Subscribe module

   ejabberd's Publish-Subscribe module integrates enhancements
   coming from J-EAI, an XMPP-based integration server built on
   ejabberd. ejabberd thus supports Publish-Subscribe node
   configuration. It is possible to define nodes that should be
   persistent, and the number of items to persist. Besides that, it
   is also possible to define various notification parameters, such
   as the delivery of the payload with the notifications, and the
   notification of subscribers when some changes occur on items.
   Other examples are: the maximum size of the items payload, the
   subscription approvers, the limitation of the notification to
   online users only, etc.


Code reorganisation and update

   - The mod_register module has been cleaned up.
   - ODBC support has been updated and several bugs have been fixed.


Development API

   To ease the work of Jabber/XMPP developers, a filter_packet hook
   has been added. As a result it is possible to develop plugins to
   filter or modify packets flowing through ejabberd.


Translations

   - Translations have been updated to support the new Publish-Subscribe features.
   - A new Brazilian Portuguese translation has been contributed.


Web interface

   - The CSS stylesheet from the web interface is W3C compliant.


Installers

   Installers are provided for Microsoft Windows and Linux/x86. The
   Linux installer includes Erlang ASN.1 modules for LDAP
   authentication support.


Bugfixes

   - This release contains several bugfixes and architectural
     changes. Among other bugfixes include improvements in LDAP
     authentication. Please refer to the ChangeLog file supplied 
     with this release regarding all improvements in ejabberd.


References

   The ejabberd feature sheet helps comparing with other Jabber/XMPP 
   servers:
   http://www.process-one.net/en/projects/ejabberd/docs/features.pdf

   Contributed tutorials of interest are:
   - Migration from Jabberd1.4 to ejabberd:
     http://ejabberd.jabber.ru/jabberd1-to-ejabberd
   - Migration from Jabberd2 to ejabberd:
     http://ejabberd.jabber.ru/jabberd2-to-ejabberd
   - Transport configuration for connecting to other networks:
     http://ejabberd.jabber.ru/tutorials-transports

END

B.4  ejabberd 1.0.0

       Release Notes
       ejabberd 1.0.0
       14 December 2005

   This document describes the main changes in ejabberd 1.0.0. Unique in this
   version is the compliancy with the XMPP (eXtensible Messaging and Presence
   Protocol) standard. ejabberd is the first Open Source Jabber server claiming
   to fully comply to the XMPP standard.

   ejabberd can be downloaded from the Process-one website:
   http://www.process-one.net/en/projects/ejabberd/

   Detailed information can be found in the ejabberd Feature Sheet and User
   Guide which are available on the Process-one website:
   http://www.process-one.net/en/projects/ejabberd/docs.html


   Recent changes include:


Server-to-server Encryption for Enhanced Security

  - Support for STARTTLS and SASL EXTERNAL to secure server-to-server traffic
    has been added.
  - Also, STARTTLS and Dialback has been implemented for server-to-server (s2s)
    connections. Detailed information about these new features can be found on
    http://ejabberd.jabber.ru/s2s-encryption
  - commonName and dNSName fields matching were introduced to ease the process
    of retrieving certificates.
  - Different certificates can be defined for each virtual host.

ODBC Support

  - ODBC support has been improved to allow production use of ejabberd with
    relational databases.
  - Support for vCard storage in ODBC has been added.
  - ejd2odbc.erl is a tool to convert an installation from Erlang's database
    Mnesia to an ODBC compatible relational database.

Native PostgreSQL Support

  - Native PostgreSQL support gives you a better performance when you use
    PostgreSQL.

Shared Roster groups

  - Shared Roster groups support has been enhanced. New is the ability to add
    all registered users to everyone's roster. Detailed information about this
    new feature can be found on http://ejabberd.jabber.ru/shared-roster-all

Web Interface

   - The web interface internal code has been modified for better integration
     and compliancy with J-EAI, an ejabberd-based Enterprise Application
     Integration platform.
   - More XHTML 1.0 Transitional compliancy work was done.

Transports

   - A transport workaround can be enabled during compilation. To do this, you
     can pass the "--enable-roster-gateway-workaround" option to the configure
     script. (./configure --enable-roster-gateway-workaround)
     This option allows transports to add items with subscription "to" in the
     roster by sending <presence type='subscribed'/> stanza to user. This option
     is only needed for JIT ICQ transport.
     Warning: by enabling this option, ejabberd will not be fully XMPP compliant
              anymore.

Documentation and Internationalization

   - Documentation has been extended to cover more topics.
   - Translations have been updated.

Bugfixes

   - This release contains several bugfixes.
   - Among other bugfixes include improvements to the client-to-server (c2s)
     connection management module.
   - Please refer to the ChangeLog file supplied
     with this release regarding all improvements in ejabberd.


   Installation Notes


Supported Erlang Version

   - You need at least Erlang/OTP R9C to run ejabberd 1.0.0.

Installation

   Installers are provided for Microsoft Windows and Linux/x86.
   Installers can be retrieved from:
   http://www.process-one.net/en/projects/ejabberd/download.html

Migration Notes

   - Before any migration, ejabberd system and database must be properly
     backed up.
   - When upgrading an ODBC-based installation, you will need to change the
     relational database schema. The following SQL commands must be run on the
     database:
       CREATE SEQUENCE spool_seq_seq;
       ALTER TABLE spool ADD COLUMN seq integer;
       ALTER TABLE spool ALTER COLUMN seq SET DEFAULT nextval('spool_seq_seq');
       UPDATE spool SET seq = DEFAULT;
       ALTER TABLE spool ALTER COLUMN seq SET NOT NULL;

References

   Contributed tutorials of interest are:
   - Migration from Jabberd1.4 to ejabberd:
     http://ejabberd.jabber.ru/jabberd1-to-ejabberd
   - Migration from Jabberd2 to ejabberd:
     http://ejabberd.jabber.ru/jabberd2-to-ejabberd
   - Transport configuration for connecting to other networks:
     http://ejabberd.jabber.ru/tutorials-transports

END

B.5  ejabberd 1.1.0

    Release Notes
    ejabberd 1.1.0
    24 April 2006

   This document describes the main changes in ejabberd 1.1.0. This version
   introduce new features including support for new Jabber Enhancement
   Proposals and several performance improvements enabling deployments on an
   even larger scale than already possible.

   ejabberd can be downloaded from the Process-one website:
   http://www.process-one.net/en/projects/ejabberd/

   Detailed information can be found in the ejabberd Feature Sheet and User
   Guide which are available on the Process-one website:
   http://www.process-one.net/en/projects/ejabberd/docs.html

   A complete list of changes is available from:
   http://support.process-one.net/secure/ReleaseNote.jspa?projectId=10011&styleName=Html&version=10025


   Recent changes include:


New Jabber Enhancement Proposal support:

  - JEP-0050: Ad-Hoc Commands.
  - JEP-0138: Stream Compression.
  - JEP-0175: SASL anonymous.

Anonymous login

  - SASL anonymous.
  - Anonymous login for clients that do not yet support SASL Anonymous.
  
Relational database Support

  - MySQL is now fully supported through ODBC and in native mode.
  - Various improvements to the native database interfaces.
  - The migration tool can use relational databases.

Multi-User Chat improvements

  - Logging of room discussion to text file is now supported.
  - Better reconfiguration support.
  - Security oriented fixes.
  - Several improvements and updates to latest JEP-0045.

Performance scalability improvements for large clusters

  - Improved session synchronisation management between cluster nodes.
  - Internal architecture has been reworked to use generalize Erlang/OTP
    framework usage.
  - Speed improvement on logger.
  - TCP/IP packet reception change for better network throttling and
    regulation.
  As a result, these improvements will reduce load on large scale deployments.

XMPP Protocol related improvements

  - XML stanza size can be limited.
  - Messages are send to all resources with the same highest priority.

Documentation and Internationalization

   - Documentation has been extended to cover more topics.
   - Translations have been updated.

Web interface

   - XHTML 1.0 compliance.

Bugfixes

   - This release contains many bugfixes on various areas such as Publish-Subscribe, build
     chain, installers, IRC gateway, ejabberdctl, amongst others.
   - Please refer to the ChangeLog file supplied with this release regarding
     all improvements in ejabberd.



   Installation Notes

Supported Erlang Version

   - You need at least Erlang/OTP R9C-2 to run ejabberd 1.1.0.

Installation

   Installers are provided for Microsoft Windows, Linux/x86 and MacOSX/PPC.
   Installers can be retrieved from:
   http://www.process-one.net/en/projects/ejabberd/download.html

Migration Notes

   - Before any migration, ejabberd system and database must be properly
     backed up.
   - The database schema has not been changed comparing to version 1.0.0 and
     consequently it does not require any migration.


References

   Contributed tutorials and documents of interest are:
   - Migration from Jabberd1.4, Jabberd2 and WPJabber to ejabberd:
     http://ejabberd.jabber.ru/migrate-to-ejabberd     
   - Transport configuration for connecting to other networks:
     http://ejabberd.jabber.ru/tutorials-transports
   - Using ejabberd with MySQL native driver:
     http://support.process-one.net/doc/display/MESSENGER/Using+ejabberd+with+MySQL+native+driver
   - Anonymous User Support:
     http://support.process-one.net/doc/display/MESSENGER/Anonymous+users+support
   - Frequently Asked Questions:
     http://ejabberd.jabber.ru/faq

END

B.6  ejabberd 1.1.1

    Release Notes
    ejabberd 1.1.1 
    28 April 2006

   This document describes the main changes in ejabberd 1.1.x. This version
   introduce new features including support for new Jabber Enhancement
   Proposals and several performance improvements enabling deployments on an
   even larger scale than already possible.

   This release fix a security issue introduced in ejabberd 1.1.0. In SASL
   mode, anonymous login was enabled as a default. Upgrading ejabberd 1.1.0 to
   ejabberd 1.1.1 is highly recommended.

   ejabberd can be downloaded from the Process-one website:
   http://www.process-one.net/en/projects/ejabberd/

   Detailed information can be found in the ejabberd Feature Sheet and User
   Guide which are available on the Process-one website:
   http://www.process-one.net/en/projects/ejabberd/docs.html

   A complete list of changes is available from:
   http://support.process-one.net/secure/ReleaseNote.jspa?projectId=10011&styleName=Html&version=10025


   Recent changes include:


New Jabber Enhancement Proposal support:

  - JEP-0050: Ad-Hoc Commands.
  - JEP-0138: Stream Compression.
  - JEP-0175: SASL anonymous.

Anonymous login

  - SASL anonymous.
  - Anonymous login for clients that do not yet support SASL Anonymous.
  
Relational database Support

  - MySQL is now fully supported through ODBC and in native mode.
  - Various improvements to the native database interfaces.
  - The migration tool can use relational databases.

Multi-User Chat improvements

  - Logging of room discussion to text file is now supported.
  - Better reconfiguration support.
  - Security oriented fixes.
  - Several improvements and updates to latest JEP-0045.

Performance scalability improvements for large clusters

  - Improved session synchronisation management between cluster nodes.
  - Internal architecture has been reworked to use generalize Erlang/OTP
    framework usage.
  - Speed improvement on logger.
  - TCP/IP packet reception change for better network throttling and
    regulation.
  As a result, these improvements will reduce load on large scale deployments.

XMPP Protocol related improvements

  - XML stanza size can be limited.
  - Messages are send to all resources with the same highest priority.

Documentation and Internationalization

   - Documentation has been extended to cover more topics.
   - Translations have been updated.

Web interface

   - XHTML 1.0 compliance.

Bugfixes

   - This release contains many bugfixes on various areas such as Publish-Subscribe, build
     chain, installers, IRC gateway, ejabberdctl, amongst others.
   - Please refer to the ChangeLog file supplied with this release regarding
     all improvements in ejabberd.



   Installation Notes

Supported Erlang Version

   - You need at least Erlang/OTP R9C-2 to run ejabberd 1.1.0.

Installation

   Installers are provided for Microsoft Windows, Linux/x86 and MacOSX/PPC.
   Installers can be retrieved from:
   http://www.process-one.net/en/projects/ejabberd/download.html

Migration Notes

   - Before any migration, ejabberd system and database must be properly
     backed up.
   - The database schema has not been changed comparing to version 1.0.0 and
     consequently it does not require any migration.


References

   Contributed tutorials and documents of interest are:
   - Migration from Jabberd1.4, Jabberd2 and WPJabber to ejabberd:
     http://ejabberd.jabber.ru/migrate-to-ejabberd     
   - Transport configuration for connecting to other networks:
     http://ejabberd.jabber.ru/tutorials-transports
   - Using ejabberd with MySQL native driver:
     http://support.process-one.net/doc/display/MESSENGER/Using+ejabberd+with+MySQL+native+driver
   - Anonymous User Support:
     http://support.process-one.net/doc/display/MESSENGER/Anonymous+users+support
   - Frequently Asked Questions:
     http://ejabberd.jabber.ru/faq

END

B.7  ejabberd 1.1.2

    Release Notes
    ejabberd 1.1.2
         27 September 2006

   This document describes the main changes in ejabberd 1.1.2.

   This version is a major improvement over ejabberd 1.1.1, improving the
   overall behaviour of the server in many areas. Users of ejabberd 1.1.1
   should upgrade to this new release for improved robustness and compliance.

   ejabberd can be downloaded from the Process-one website:
   http://www.process-one.net/en/projects/ejabberd/

   Detailed information can be found in the Feature Sheet and in the
   Installation and Operation Guide which are both available on the
   Process-one website:
   http://www.process-one.net/en/projects/ejabberd/docs.html

   ejabberd includes 44 improvements. A complete list of changes can be
   retrieved from:
   http://redir.process-one.net/ejabberd-1.1.2


   Recent changes include:

LDAP Improvements

  - Major improvements have been made on the LDAP module. It is now more
    flexible and more robust.

HTTP Polling Fixes

  - The HTTP polling modules have been fixed and improved: the connections are
    closed properly and polled messages cannot be lost anymore.

Roster Management Improvement

  - Roster management improvements increase reliability, especially in cases
  where users are on different servers.
  - Shared rosters are more reliable.

Improved Robustness

  - It is now possible to limit the number of opened connections for a single
  user.

Relational databases

  - Database support: Microsoft SQL Server is now officially supported in ODBC
  mode.

Publish-Subscribe Improvement

  - Restricting node creation with a dedicated ACL rule is now possible.

Localization

  - A Czech translation has been added.
  - Translations have been updated.

Binary Installer

  - New binary installer for Windows including all requirements.
  - Improved installers for Linux and MacOSX (PowerPC)

XMPP Compliancy

  - Some protocol compliance fix have been added, after the Portland XMPP
    Interop Meeting in July.

Miscelanous

  - MUC have been improved (logging rendering).
  - The command line tool ejabberdctl has been improved.
  - The build chain has been improved, including MacOSX support.
  - The documentation has been improved and updated to describe the new
    features.

Bugfixes

   - Anonymous login bugfixes.
   - Please refer to the ChangeLog file supplied with this release regarding
     all improvements in ejabberd.


   Installation Notes

Supported Erlang Version

   - You need at least Erlang/OTP R9C-2 to run ejabberd 1.1.2.
   - The recommanded version is Erlang/OTP R10B-10.
   - Erlang/OTP R11B has not yet been fully certified for ejabberd.

Installation

   Installers are provided for Microsoft Windows, Linux/x86 and MacOSX/PPC.
   They can be retrieved from:
   http://www.process-one.net/en/projects/ejabberd/download.html

Migration Notes

   - Before any migration, ejabberd system and database must be properly
   backed up.
   - The relational database schema has changed between version 1.1.1 and
   1.1.2. An "askmessage" column needs to be added in the "rosterusers" table
   to perform the migration.


References

   Contributed tutorials and documents of interest are:
   - Migration from other XMPP servers to ejabberd:
     http://ejabberd.jabber.ru/migrate-to-ejabberd     
   - Transport configuration for connecting to other networks:
     http://ejabberd.jabber.ru/tutorials-transports
   - Frequently Asked Questions:
     http://ejabberd.jabber.ru/faq

END

C  Acknowledgements

Thanks to all people who contributed to this guide:

D  Copyright Information

Ejabberd Installation and Operation Guide.
Copyright © January 23, 2003 — Alexey Shchepin

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.