Monday, August 06, 2007

How to Set Up a Jabber Server

By Suramya Tomar

1.0 Introduction:

Unless you have been living under a rock for the past few years, you must have heard about instant messaging and how it has changed the world of communications over the Internet. According to http://www.webopedia.com, Instant Messaging (IM) is a service that alerts users when their friends or colleagues are on line and allows them to communicate in real time through private online chat areas. Two of the most popular IM services are AOL Instant Messenger (AIM) and MSN Messenger. Unfortunately, most of the publicly available servers use proprietary protocols that only allow you to communicate with users on the same system. These systems are not compatible with each other and can't be accessed from other clients.
Jabber is an open source implementation of the IM server that aims to change this. It uses streaming XML protocols that are free, open, and public. These protocols have been formalized by the Internet Engineering Task Force (IETF) as the approved instant messaging and presence technology under the name of XMPP. The first Jabber technologies were developed in 1998 by Jeremie Miller and is now used on thousands of servers world-wide to enable millions of users to communicate with each other.
The biggest advantage of the Jabber server when compared with commercial IM servers is that, since it is open source, anyone can run a Jabber server and it can be restricted to a specific community like a company work force or a group of friends. In this article, I will document the steps I took to set up a Jabber server and how I managed to overcome the difficulties I faced. Hopefully this will make it easier for you to set up your own Jabber server.

2.0 Pre-Configuration

Before we compile the server, we need to make some changes to the system on which we'll be installing the server to make it more secure. The first thing we have to do is create a new user so the Jabberd server process is not run as root. This is highly recommended, since running server processes as root is a pretty bad idea.
Now, you might be wondering why that's the case. Right? Well, imagine this scenario: a buffer overflow flaw is discovered in the Jabberd server code and before a fix for it has been written a script-kiddy who has hated you since you stole his place in the 5th grade cafeteria finds out that you are running a version of the server that is vulnerable to the attack and decides to hack you. Now, if you are running the server as root, he would have you at his mercy, as he would have full control of the server and he could do whatever he wanted with it. On the other hand, if you were running it as another user, he would still have to jump through a lot of hoops to get root access and hopefully he would set off some kind of alarm before he gets it, allowing you to catch him. Convinced yet? No? Well it's your funeral...
To add a user to the server, run the following command as root: adduser jabber. Then, choose a password for the account by running the following command: passwd jabber.
After changing the password, we need to create a directory where the jabberd process will store its logs and pids. You do it by running the following commands:

mkdir -p /usr/local/var/jabberd/pid/
mkdir -p /usr/local/var/jabberd/log/
Once the directories are created, we need to change the ownership of the directories so that the user jabber can write to them. We do this by running the following commands:

chown -R jabber:jabber /usr/local/var/jabberd/pid/
chown -R jabber:jabber /usr/local/var/jabberd/log

2.1 Getting the Jabber Server

Since Jabber is an Open Source project, there are multiple implementations of the Jabber server. A list of some of the servers is available at: http://www.jabber.org/software/servers.shtml. I decided to use the Jabberd 2.x implementation of the server as I already had the source for the server on my computer. Also, it wasn't possible to download another server source due to the recent hack of the Jabber Studio servers and the subsequent shutdown of the download section of the site while they figured out what was going on.
Hopefully, by the time you read this, their machines should be back to normal and you will be able to download the latest version of Jabberd from their site.

2.2 Configuring and Installing Jabber

First thing we have to do after we download the source is to uncompress it by issuing the following command: tar -zxf jabberd-2.0s2.tar.gz. Then we change our current working directory to the jabberd source directory by issuing the following command: cd jabberd-2.0s2
The jabberd server has a lot of configuration options that can be set during the initial configuration. To see a list of all the options available run the following command: ./configure --help. I decided to go with the default settings so I used the following command to configure the install process: ./configure
Once the configure script has finished running without giving any errors, we can go ahead and compile the program by issuing the following command: make. Once this is done, we install the server by running: make install as root.
By default, jabberd uses MySQL to store the user data, so we'll need to setup a new MySQL database that jabberd can access. There is a script in the 'tools' subdirectory of the jabberd source that makes this really easy to do. To run the script issue the following command:
mysql -u root -p  < tools/db-setup.mysql
Enter the MySQL root password when you are prompted for it. This script creates a new database and populates it with tables that the jabberd server requires. Once the script finishes running, we need to create a user called jabberd2 in MySQL to allow jabberd to manipulate the database. This is done by issuing the following command:
mysql -u root -p.
Now enter the root password when you are prompted for it and you will get the MySQL command prompt. At this prompt enter the following command:
GRANT select,insert,delete,update ON jabberd2.* to jabberd2 at localhost IDENTIFIED by 'examplepassword';
replacing "examplepassword" with a password of your choice. Once you run this command type exit to exit the program. This finishes the installation of the jabberd server. Now we need to customize the server for our use.

2.3 Customizing the jabberd server install

To customize the server, we first need to change to the jabberd directory by running the following command: cd /usr/local/etc/jabberd/. Then we want to edit the sm.xml file so we follow the following steps as root:
  • Open sm.xml in your favorite text editor
  • Change the ID on the network from localhost to jabber.yoursite.com (Make sure that jabber.yoursite.com resolves)
  • Scroll down to the User Options and uncomment the <auto-create/> tag. This allows users that are not registered on the server to register themselves.
  • If you want to have a predefined userlist to populate all new users, scroll to the the end of the file and uncomment <roster>/usr/local/etc/jabberd/templates/roster.xml</roster>. We will cover the contents of the roster.xml in a few minutes.
Once we are done editing, save sm.xml and exit the editor. Now we need to customize c2s.xml, so follow these steps as root:
  • Open c2s.xml in your favorite text editor
  • Scroll to the 'Local network configuration' section and change the <id> from localhost to jabber.yoursite.com
  • Save and exit
This completes the configuration of the jabberd server. This gives us a basic jabber server that allows users to register themselves and chat with each other. However, if we want to have the ability to create chat rooms, we need to install some additional software called mu-conference. We will cover the installation of mu-conference momentarily.

2.4 Creating a default buddy list for new users

jabberd gives us the ability to create a template buddy list so that each new user has a default buddy list. This is very useful in environments where the administrator wants to make sure each user has all the important people in their buddy list without spending a lot of time adding each user manually.
The template file is located in the templates subdirectory and is called roster.xml. The file has the following format:
<query xmlns='jabber:iq:roster'>
<!--
<item name='Buddy Name' jid='JID@Host.domain' subscription='both'>
<group>BuddyGroup</group>
</item>
-->
</query>
To add new users we need to uncomment the <item name> tag and add a new line for each user. For example if you wanted to add me to the default roster and my JID (Jabber ID) was suramya@jabber.suramya.com the entry for my name would look like this:
<item name='Suramya'  jid='suramya@jabber.suramya.com' subscription='both'>
<group>Support</group>
</item>
The group field tells the client the group under which the entry is supposed to be stored. In this case Suramya is being stored under the Support group. All entries need to be enclosed within the <query> </query> tag, so the complete file with one user would look something like:
<query xmlns='jabber:iq:roster'>
<item name='Suramya' jid='suramya@jabber.suramya.com' subscription='both'>
<group>Support</group>
</item>
</query>

2.5 Install mu-conference server

Before we can install mu-server we need to install the Jabber Component Runtime(JCR) which is available for download at: http://jabber.terrapin.com/JCR/jcr-0.1.2.tar.gz. To download and install JCR follow these steps:
  • Download the source using: wget http://jabber.terrapin.com/JCR/jcr-0.1.2.tar.gz
  • Uncompress the archive using: tar -zxf jcr-0.1.2.tar.gz
  • Change to the jcr source directory using: cd jcr-0.1.2
  • Compile jcr by running: make
Once jcr finishes compiling we can proceed with the installation of mu-conference by following these steps:
  • Download the mu-conference source in the jcr directory from here
  • Uncompress the archive using: tar -zxf mu-conference-0.6.0.tar.gz
  • Copy main.c to the src directory using the following command: cp src/main.c mu-conference-0.6.0/src
  • Copy jcomp.mk to the src directory using the following command: cp src/jcomp.mk mu-conference-0.6.0/src
  • Change to the mu-conference source directory using: cd mu-conference-0.6.0/src
  • Compile mu-conference using: make -f jcomp.m
  • Copy the mu-conference executable created to the jabberd folder using: cp mu-conference /usr/local/bin
  • Copy the Configuration file to jabberd configuration folder using: cp ../muc-jcr.xml /usr/local/etc/jabberd/
Now we have to customize mu-conference by editing muc-jcr.xml. To customize the conference follow these steps:
  • Open muc-jcr.xml in your favorite text editor
  • Change the name and host fields to conference.yoursite.com
  • Add <user>jabberd</user> before the 'secret' line
  • Change the spool, logdir and pidfile lines to:
    • /usr/local/var/jabberd/spool
    • /usr/local/var/jabberd/log
    • usr/local/var/jabberd/pid
  • Create the spool directory using: mkdir -p /usr/local/var/jabberd/spool/
This finishes the configuration of the mu-conference server and we are now ready to run it.

2.5 Running the Jabberd server

To run the server run the following commands:
  • Switch to the jabber user using: su jabber
  • Start the jabberd server process using: /usr/local/bin/jabberd &
  • Start the mu-conference server using: /usr/local/bin/mu-conference -c /etc/jabberd/muc-jcr.xml &

3.0 Conclusion

By now I have hopefully saved you a lot of trouble by telling you how to setup a jabber server quickly and easily. If you think this document helped you or you have some comments or questions about this please feel free to contact me and let me know. However I must warn you that I am a somewhat lazy person who might take a little while before replying to your emails.
Thanks for your time -
Suramya Tomar

4.0 Document Information/History

Created by: Suramya Tomar
Last updated: 14th February 2005

4.1 Copyright

This document is Copyright © 14th July 2005, Suramya Tomar.
It is released to the public under the Creative Commons Attribution-ShareAlike 1.0 License

4.2 Credits

In this section I have the pleasure of acknowledging the following people without whose input this would have never seen the light of the day:
  • The creators and maintainers of http://www.jabber.com from where I compiled most of this information
  • Alf Eaton for posting the steps he took to get the Jabber conference feature working
  • Renny Koshy for letting me try setting up a Jabber server on his machine
  • Matt Hoskins and Kevin Walsh, for getting me interested in Linux in the first place.
  • My friends and family, for bearing with me when I was compiling this document


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