Ejabberd Installation and Operation Guide

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

January 26, 2003

1 Introduction

ejabberd is a Free and Open Source distributed fault-tolerant Jabber server. It writen mostly in Erlang.

TBD

2 Installation

2.1 Installation Requirements

To compile ejabberd, you need following packages:

GNU Make;
GCC;
libexpat 1.95 or later;
Erlang/OTP R8B or later.

2.2 Obtaining

Currently no stable version released.

Latest alpha version can be retrieved via CVS. Do following steps:

export CVSROOT=:pserver:cvs@www.jabber.ru:/var/spool/cvs
cvs login
Enter empty password
cvs -z3 co ejabberd

2.3 Compilation

3 Configuration

3.1 Initial Configuration

Configuration file is loaded after first start of ejabberd. It consists of sequence of Erlang terms. Parts of lines after `%' sign are ignored. Each term is tuple, where first element is name of option, and other are option values.

3.1.1 Host Name

Option hostname defines name of Jabber domain that ejabberd serves. E. g. to use jabber.org domain add following line in config:

{host, "jabber.org"}.

3.1.2 Listened Sockets

Option listen defines list of listened sockets and what services runned on them. Each element of list is a tuple with following elements:

Port number;
Module that serves this port;
Function in this module that starts connection (likely will be removed);
Options to this module.

Currently three modules implemented:

ejabberd_c2s: serves C2S connections;
ejabberd_s2s_in: serves incoming S2S connections;
ejabberd_service: serves connections to Jabber services (i. e. that use jabber:component:accept namespace).

For example, following configuration defines that C2S connections listened on port 5222, S2S on port 5269 and that service conference.jabber.org must be connected to port 8888 with password ``secret''.

{listen, [{5222, ejabberd_c2s,     start, []},
          {5269, ejabberd_s2s_in,  start, []},
          {8888, ejabberd_service, start, ["conference.jabber.org", "secret"]}
         ]}.

3.1.3 Access Rules

Access control in ejabberd is done via Access Control Lists (ACL). In config file they looks like this:

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

<acltype> can be one of following:

all

Matches all JIDs. Example:

{acl, all, all}.

{user, <username>}

Matches local user with name <username>. Example:

{acl, admin, {user, "aleksey"}}.

{user, <username>, <server>}

Matches user with JID <username>@<server>. Example:

{acl, admin, {user, "aleksey", "jabber.ru"}}.

{server, <server>}

Matches any JID from server <server>. Example:

{acl, jabberorg, {server, "jabber.org"}}.

Allowing or denying of different services is like this:

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

When JID is checked to have access to <accessname>, server sequentially checks if this JID in one of the ACLs that are second elements in eache tuple in list. If one of them matched, then returned first element of matched tuple. Else returned ``deny''.

Example:

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

3.1.4 Modules

Option modules defines list of modules that will be loaded after ejabberd startup. Each list element is a tuple where first element is a name of module and second is list of options to this module. See section 5 for detailed information on each module.

Example:

{modules, [
           {mod_register,  []},
           {mod_roster,    []},
           {mod_configure, []},
           {mod_disco,     []},
           {mod_stats,     []},
           {mod_vcard,     []},
           {mod_offline,   []},
           {mod_echo,      [{host, "echo.localhost"}]},
           {mod_private,   []},
           {mod_time,      [{iqdisc, no_queue}]},
           {mod_version,   []}
          ]}.

3.2 Online Configuration

To use facility of online reconfiguration of ejabberd needed to have mod_configure loaded (see section 5.4). Also highly recommended to load mod_disco (see section 5.5), because mod_configure highly integrates with it. Also recommended to use disco- and xdata-capable client.

TBD

4 Distribution

4.1 How it works

Jabber domain is served by one or more ejabberd nodes. This nodes can be runned on different computers that can be connected via network. They all must have access to connect to port 4369 of all another nodes, and must have same magic cookie (see Erlang/OTP documentation, in short file ejabberd/.erlang.cookie must be the same on all nodes). This is needed because all nodes exchange information about connected users, S2S connection ,registered services, etc...

Each ejabberd node run following modules:

router;
local router.
session manager;
S2S manager;

4.1.1 Router

This module is the main router of Jabber packets on each node. It route them based on their destanations domains. It have two tables: local and global routes. First, domain of packet destination searched in local table, and if it finded, then packet routed to appropriate process. If no, then it searched in global table, and routed to appropriate ejabberd node or process. If it not exists in both tables, then it sended to S2S manager.

4.1.2 Local Router

This module route packets which have destination domain equal to this server name. If destination JID have node, then it routed to session manager, else it processed depending on it content.

4.1.3 Session Manager

This module route packets to local users. It search to what user resource packet must be sended via presence table. If this reseouce connected to this node, it routed to C2S process, if it connected via another node, then packet sended to session manager on it.

4.1.4 S2S Manager

This module route packets to another Jabber servers. First, it check if to domain of packet destination from domain of source already opened S2S connection. If it opened on another node, then it routed to S2S manager on that node, if it opened on this node, then it routed to process that serve this connection, and if this connection not exists, then it opened and registered.

5 Built-in Modules

5.1 Common Options

Following options used by many modules, so they described in separate section.

5.1.1 Option `iqdisc`

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

no_queue: All queries of namespace with this processing discipline processed immediately. This also means that no other packets can be processed until finished this. Hence this discipline is not recommended if processing of query can take relative many time.
one_queue: In this case created separate queue for processing IQ queries of namespace with this discipline, and processing of this queue done in parallel with processing of other packets. This discipline is most recommended.
parallel: In this case for all packets of namespace with this discipline spawned separate Erlang process, so all this packets processed in parallel. Although spawning of Erlang process have relative low cost, this can broke server normal work, because Erlang have limit of 32000 processes.

Example:

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

5.1.2 Option `host`

Some modules may act as services, and wants to have different domain name. This option explicitly defines this name.

Example:

{modules, [
           ...
           {mod_echo,      [{host, "echo.myjabber.org"}]},
           ...
          ]}.

5.2 `mod_register`

5.3 `mod_roster`

5.4 `mod_configure`

5.5 `mod_disco`

5.6 `mod_stats`

This module adds support of JEP-0039 (Statistics Gathering).

Options:

iqdisc: http://jabber.org/protocol/stats IQ queries processing discipline.

TBD about access.

5.7 `mod_vcard`

5.8 `mod_offline`

5.9 `mod_echo`

5.10 `mod_private`

This module adds support of JEP-0049 (Private XML Storage).

Options:

iqdisc: jabber:iq:private IQ queries processing discipline.

5.11 `mod_time`

This module answers UTC time on jabber:iq:time queries.

Options:

iqdisc: jabber:iq:time IQ queries processing discipline.

5.12 `mod_version`

This module answers ejabberd version on jabber:iq:version queries.

Options:

iqdisc: jabber:iq:version IQ queries processing discipline.

This document was translated from L^AT_EX by H^EV^EA.