Ejabberd 0.9.9-alpha Installation and Operation Guide

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




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

Table of Contents

1  Introduction

ejabberd is a free (GPL) distributed fault-tolerant Jabber/XMPP server and is mainly written in Erlang.

ejabberd is designed to be a stable and feature rich Jabber/XMPP server.

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

1.1  Key Features

ejabberd is:

1.2  Additional Features

Besides common Jabber server features, ejabberd comes with a wide range of other 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:

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 can't 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  Configuration

3.1  Initial 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.

3.1.1  Host Names

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

Examples:

3.1.2  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 for the option language is "en". In order to take effect there must be a translation file <language>.msg in ejabberd's msgs directory.

Examples:

3.1.3  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 ``deny'' is returned.

Example: 
  {access, configure, [{allow, admin}]}.
  {access, something, [{deny, badmans},
                       {allow, all}]}.
The following access rules are pre-defined:
all
Always returns ``allow''
none
Always returns ``deny''

3.1.4  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:

3.1.5  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, shaper, ssl, tls, starttls,
    starttls_required
ejabberd_s2s_in Description Handles incoming s2s connections.
  Options inet6, ip
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}}.
{shaper, <access rule>}
This option defines a shaper for the port (see section 3.1.4). 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.
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.
Also the following global 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 the SSL certificate.
{domain_certfile, Domain, Path}
Path to a file containing the SSL certificate for 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>

3.1.6  Modules

The option modules defines the list of modules that will be loaded after ejabberd 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. Read section A for detailed information about each module.

Example: 
  {modules,
   [{mod_register,  []},
    {mod_roster,    []},
    {mod_privacy,   []},
    {mod_configure, []},
    {mod_disco,     []},
    {mod_stats,     []},
    {mod_vcard,     []},
    {mod_offline,   []},
    {mod_announce,  [{access, announce}]},
    {mod_echo,      [{hosts, ["echo.example.org"]}]},
    {mod_private,   []},
    {mod_irc,       []},
    {mod_muc,       []},
    {mod_pubsub,    []},
    {mod_time,      [{iqdisc, no_queue}]},
    {mod_last,      []},
    {mod_version,   []}
   ]}.

3.1.7  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:

3.2  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 3.3.2): 
      % ejabberdctl node@host register admin example.org password
    2. Using In-Band Registration (see section A.12): 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.

3.3  Online Configuration and Monitoring

3.3.1  Web Interface

To perform online configuration of ejabberd you need to enable the ejabberd_http listener with the option web_admin (see section 3.1.5). 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.

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:

3.3.2  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 jabberd 1.4 and to migrate from jabberd2.
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  Firewall Settings

You need to take the following 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 6).
port range Only for clustring (see 6). This range is configurable (see 2.4).

5  SRV Records

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 as the `ejabberd' user in the directory where ejabberd will work later the following command: 
    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 `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 don't 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  Built-in Modules

A.1  Common Options

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

A.1.1  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}]},
    ...
   ]}.

A.1.2  hosts

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

Examples:

A.2  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 A.8) 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:

A.3  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 A.1.1).
extra_domains
With this option, extra domains can be added to the Service Discovery item list.
Examples:

A.4  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 A.1.2). If neither hosts nor the old host is present, the prefix ``echo.'' is added to all ejabberd hostnames.
Examples:

A.5  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 A.1.2). 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:

A.6  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 A.1.1).

A.7  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 A.1.2). 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).
Examples:

A.8  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 3.3.2).

A.9  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 A.1.1).

A.10  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 A.1.1).

A.11  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 A.1.2). 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.
Example: 
  {modules,
   [
    ...
    {mod_pubsub, [{served_hosts, ["example.com",
                                  "example.org"]}]}
    ...
   ]}.

A.12  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 A.1.1).
Examples:

A.13  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 A.1.1).

A.14  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:

A.15  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 doesn't 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:

A.16  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 A.1.1).
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:

A.17  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 A.1.1).

A.18  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 A.1.2). 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 A.1.1).
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:

A.19  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 A.1.1).

B  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>

Figure 2: Service Discovery when xml:lang='ru'

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

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

C  Release Notes

C.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.

C.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.

C.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

D  Acknowledgements

Thanks to all people who contributed to this guide:
This document was translated from LATEX by HEVEA.