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Installing the Jabber Server

This chapter explains what you have to do to obtain, install, configure, and start up a Jabber server of your own with the minimum of fuss.

It's certainly possible to learn about the Jabber protocols and technology and develop solutions using someone else's Jabber server, but for real understanding and control, it's definitely worth setting up one of your own. By installing and configuring a Jabber server, you will gain a valuable insight into how it and its components work together. Understanding how components are controlled and configured allows us to build Jabber solutions in the context of the "big picture."

Installations of earlier versions (1.0, 1.2) of the Jabber server were often complex affairs, and while the installation process has become much more straightforward, some people still shrink back from installing and configuring their own. This chapter shows how straightforward it is.

If you already have a server set up, you might want to skip this chapter and go on to Chapter 4, where the configuration and system architecture are explained in more detail.

Although the Jabber development platform is Linux, the Jabber server will compile and run on many flavors of Unix, including FreeBSD, Solaris, AIX, and IRIX.^[1] Versions of the C compiler and make utility from the GNU project (at http://www.gnu.org) are recommended if you don't already have them installed.

The examples shown in this and other chapters are taken from Linux platforms (various Slackware and Red Hat distributions with 2.2 and 2.4 kernel versions); consult your local documentation for equivalent commands on your Unix OS.

The incarnation of the Jabber server at the time of writing is Version 1.4, more specifically 1.4.1. Version 1.4 represents a major advance in the server code and brings increases in performance and reliability over earlier versions. Jabber server Version 1.4.1 is the one we will obtain and install here, and this will be used as the server for the recipes in the rest of this book.

Downloading the Jabber Server

The Jabber server package can be obtained from the Jabber project site, http://www.jabber.org; the 1.4.1 version is available in the downloads area:

http://download.jabber.org/dists/1.4/final/jabber-1.4.1.tar. gz

you need to get a Jabber server up and running.^[2] Previous versions of the Jabber server came in multiple packages; it was necessary to separately obtain and install GNU's portable threads library (pth) and the asynchronous DNS package (ADNS), as well as obtaining and installing various Jabber-specific libraries such as libxode, libjabber, and libetherx. Now some of these libraries and packages have become obsolete as far as the Jabber server is concerned (ADNS and libetherx) and others have been combined into the main Jabber server tarball.

If you don't want to compile the server yourself, you can also download prebuilt binaries for some of the platforms already mentioned, from http://download.jabber.org.

Installing the Server

Once you have downloaded the Jabber server tarball, you need to unpack it, configure the build environment, and compile the server. The general idea is that the Jabber server will be compiled and run from wherever you decide to unpack it; that is, there is no separate "install" step.

For this reason, and because it's also often useful to be able to install and start up a different version of the Jabber server for testing and comparisons, create a generic jabber directory somewhere central but local, for example in /usr/local/:

| yak:/usr/local# mkdir jabber

The Jabber server does not need to be and should not be run as root; so create a new user jabber (group jabber) to be used as the Jabber server administrator and make that user the owner of the generic Jabber server directory:

| yak:/usr/local# groupadd jabber yak:/usr/local# useradd -g jabber -d /usr/local/jabber jabber yak:/usr/local# passwd jabber Changing password for jabber Enter the new password (minimum of 5, maximum of 127 characters) Please use a combination of upper and lower case letters and numbers. New password: ******** Re-enter new password: ******** Password changed. yak:/usr/local# chown jabber:jabber jabber yak:/usr/local#

Once you've created the generic Jabber server directory, switch to the new Jabber server administration user jabber, unpack the tarball you downloaded, and enter the resulting directory:

| yak:/usr/local# su - jabber yak:~$ tar xzf jabber-1.4.1.tar.gz yak:~$ cd jabber-1.4.1/ yak:~/jabber-1.4.1$

Running the Configure Server

Examining the contents of the jabber-1.4.1 directory, we see the following files:

• configure (the configuration script)
  
• jabber.xml (the server configuration file)
  
• Makefile (for compiling the Jabber server)
  
• README (some basic instructions)
  
• UPGRADE (information on upgrading from an earlier server version) as well as a number of directories that contain the source code.
  

The first step is to run the configure script:

| yak:~/jabber-1.4.1$ ./configure

to determine your platform's compiler settings.

If you want SSL support in the Jabber server, run the script with the --enable-ssl switch:

| yak:~/jabber-1.4.1$ ./configure --enable-ssl

If you specified the --enable-ssl switch, the configure script looks for your SSL installation and adds the appropriate compiler flags. If it doesn't find your SSL installation, it says so and your Jabber server is compiled without SSL support.

Next, it will try to determine whether you have pth installed and if so will use the pth-config command to glean the extra compiler options for building the Jabber server. pth is required, so if it isn't already installed, it will be set up within your current jabber-1.4.1 directory tree (as pth is included in the jabber-1.4.1.tar.gz tarball) and the appropriate compiler options added.

If pth is set up during the course of running configure, you may see a message: "Now please type 'make' to compile. Good luck.", which comes at the end of the pth configure procedure; you can ignore this because there is only one make step, for the Jabber server, that must be carried out as we are merely preparing the pth build environment for binding into the Jabber Server build.

Finally, after extra platform-specific compiler settings are determined, a shell script to set the build environment variables is created with the name platform-settings. This is used in the next step.

Example 3-1 shows typical output from the configure script.

Typical output from configure

| Running Jabber Configure ========================

Getting pth settings... Done. Setting Build Parameters... Done. Generating Settings Script... Done.

You may now type 'make' to build your new Jabber system.

Running make

Once the platform settings have been determined by the configure script, we are ready to build the Jabber server with make:

| yak:~/jabber-1.4.1$ make

Example 3-2 shows abbreviated typical output from the make command.

Typical output from make

| Making all in pthsock make[1]: Entering directory `/usr/local/jabber/jabber-1.4.1/pthsock' gcc -g -Wall -fPIC -I. -I.. -I/usr/local/include -I../jabberd/ -c client.c -o client.o gcc -g -Wall -fPIC -I. -I.. -I/usr/local/include -I../jabberd/ -shared -o pthsoc k_client.so client.o -L/usr/local/lib -lpth -ldl -lresolv make[1]: Leaving directory `/usr/local/jabber/jabber-1.4.1/pthsock' Making all in xdb_file make[1]: Entering directory `/usr/local/jabber/jabber-1.4.1/xdb_file' gcc -g -Wall -fPIC -I. -I.. -I/usr/local/include -I../jabberd -c xdb_file.c -o xdb_file.o

...

gcc -g -Wall -fPIC -I. -I.. -I/usr/local/include -DHOME="\"/usr/local/jabber/jab ber-1.4.1\"" -DCONFIGXML="\"jabber.xml\"" -o jabberd config.o mio.o mio_raw.o mi o_xml.o mio_ssl.o deliver.o heartbeat.o jabberd.o load.o xdb.o mtq.o static.o lo g.o lib/expat.o lib/genhash.o lib/hashtable.o lib/jid.o lib/jpacket.o lib/jutil. o lib/karma.o lib/pool.o lib/pproxy.o lib/rate.o lib/sha.o lib/snprintf.o lib/so cket.o lib/str.o lib/xmlnode.o lib/xmlparse.o lib/xmlrole.o lib/xmltok.o lib/xst ream.o lib/xhash.o base/base_connect.o base/base_dynamic.o base/base_exec.o base /base_stdout.o base/base_accept.o base/base_file.o base/base_format.o /base/base_ stderr.o base/base_to.o -Wl,--export-dynamic -L/usr/local/lib -lpth -ldl -lresol v make[2]: Leaving directory `/usr/local/jabber/jabber-1.4.1/jabberd' make[1]: Leaving directory `/usr/local/jabber/jabber-1.4.1/jabberd' make[1]: Entering directory `/usr/local/jabber/jabber-1.4.1' make[1]: Nothing to be done for `all-local'. make[1]: Leaving directory `/usr/local/jabber/jabber-1.4.1'

Configuring the Jabber Server

The nature and behavior of a Jabber server is controlled by the contents of a configuration file (with a default name of jabber.xml), which you will find in the jabber-1.4.1 directory. As you can probably guess from the filename's extension, the configuration is formatted in XML, which offers a very powerful way of expressing the nature and features of your Jabber server and associated services and components.

Details on how to navigate, interpret, and edit this configuration file are given in Chapter 4; here we will just look at the basic settings that can be modified before you start up the Jabber server.

For an experimental Jabber server (such as for the purposes of this book), there isn't actually anything you need to change in the configuration. The out-of-the-box configuration settings are pretty much what we need in order to experiment with our recipes later in the book; nevertheless, let's look at some of the settings you may wish to change right now:

Server hostname

The <host/> parameter specifies the Jabber server's

hostname. As delivered, the jabber.xml configuration has this set to

localhost: :

|<host><jabberd:cmdline flag="h">localhost</jabberd:cmdline></host>

You can change this to the name of your server hostname; in the case

of our examples, this would be yak. : The localhost setting occurs

elsewhere in the configuration too—as a literal in the welcome message

that is sent to users after a successful registration with the server.

You may wish to replace this occurrence of localhost; furthermore, you

will find other occurrences, but they are within sections of the

configuration that are commented out in the standard delivered version

of jabber.xml (specifically, administration JIDs and definitions for

various add-on agents and transports; we will cover these in the next

chapter). : One other place that localhost occurs is in the

<update/> section, which is explained next.

Server software update notification mechanism

The Jabber server development team offers a facility for servers to

check for updated versions of the Jabber server software. The facility

is addressed with this configuration setting: :

|<update><jabberd:cmdline flag="h">localhost</jabberd:cmdline></update>

which causes a versioning module, mod_version, in the Jabber Session

Manager (JSM), to send a <presence/> packet (which

carries the server version—in our case, 1.4.1) from the server to the

Jabber ID jsm@update.jabber.org when the Jabber server starts up.

 : If your server is purely internal, and/or behind a firewall, it

makes no sense to have this facility switched on (you can check for

updates to the server on the http://www.jabber.org web site) as the

<presence/> packet will never reach its intended

destination. You can comment it out like this: :

|<!-- <update><jabberd:cmdline flag="h">localhost</jabberd:cmdline></update> -->

Automatic user directory update

The configuration as delivered contains a directive: :

|<vcard2jud/>

which means that any vCard data—a vCard is a virtual "business card"

containing contact information and so on—that is maintained by a

Jabber client will be automatically passed on to the central user

directory (the Jabber User Directory, or JUD), defined elsewhere in

the jabber.xml as the one at jabber.org, users.jabber.org. :

If you've commented out the update notification mechanism because

you're not going to be able to (or want to) reach the servers at

jabber.org, then you might as well comment this out to avoid error

messages being sent to Jabber clients when vCard data is modified:  :

|<!-- <vcard2jud/> -->

Alternatively, instead of commenting out the

<vcard2jud/>, you could comment out the definition of

the JUD service in the <browse/> section: :

|<!-- <service type="jud" jid="users.jabber.org" name="Jabber User Directory"> <ns>jabber:iq:search</ns> <ns>jabber:iq:register</ns> </service> -->

because the mechanism looks in the <browse/> section

for a reference to a JUD service; if there isn't one there, no vCard

update will be sent.

You may have noticed that the values for each of these two settings (<host/> and <update/>) were wrapped in another tag:

|<jabberd:cmdline flag="h">...</jabberd:cmdline>

This means that you can override the setting with a command-line switch (or "flag"), in this case -h. So, in fact, you don't even need to modify the jabber.xml configuration at all, if you specify your hostname when you start the server up (the welcome message will not be changed, of course).

Starting and Stopping the Jabber Server

At this stage, we have a Jabber server with enough basic configuration to be able to start it up and have it do something useful (like accept client connections). If you're curious about the rest of the configuration you encountered while editing the jabber.xml file, you can jump to Chapter 4. Otherwise, let's start it up!

Starting the Server

The basic invocation looks like this:

| yak:~/jabber-1.4.1$ ./jabberd/jabberd

but if you haven't bothered to change localhost anywhere in the configuration (as described earlier), you can use the -h switch to specify the hostname:

| yak:~/jabber-1.4.1$ ./jabberd/jabberd -h yak

As it stands, there's a directive in the standard jabber.xml configuration file that specifies that any server error messages are to be written out to STDERR:

|<log id='elogger'> <host/> <logtype/> <format>%d: [%t] (%h): %s</format> <file>error.log</file> <stderr/> </log>

So either comment the directive out:

|<!-- <stderr/> -->

Or redirect STDERR to /dev/null:

| yak:~/jabber-1.4.1$ ./jabberd/jabberd -h yak 2>/dev/null

You won't lose the error messages—as you can see they're also written to the error.log file.

Assuming you wish to free up the terminal session after starting the server, you can send it to the background:

| yak:~/jabber-1.4.1$ ./jabberd/jabberd -h yak 2>/dev/null &

Connecting a Client

Once the server is started, you're ready to start up a client and make a connection. The thing to remember at this point, when specifying which server to connect to, is to use the same hostname as you specified in the <host/> part of the configuration, described earlier in Section 3.3.

Stopping the Server

To stop the server, just kill the processes, and it will shut down:

| yak:~/jabber-1.4.1$ killall jabberd

or:

| yak:~/jabber-1.4.1$ kill `cat jabber.pid`

jabberd Command-Line Switches

We've seen the -h switch to specify the host when starting the server up. There are other switches available on the command line, too; they are listed in Table 3-1.

Starting the Jabber server with any unrecognized switches will cause it to show you a list of valid switches:

| [yak: ~/jabber-1.4.1]$ ./jabberd/jabberd -badswitch Usage: jabberd & Optional Parameters: -c configuration file -D enable debug output -H location of home folder -v server version -V server version

Yes, the list that it shows isn't complete. If the common switch -h were present in the list, we could almost consider the unlisted switches as undocumented, but it isn't present, so we won't.

Monitoring and Troubleshooting the Server

We've already seen a glimpse of the configuration relating to logging of messages in the previous section. As standard, the Jabber server configuration describes two types of logging record and a recipient file for each type:

Error logging

Error log records are written to error.log in the current directory,

as determined thus: :

|<log id='elogger'> <host/> <logtype/> <format>%d: [%t] (%h): %s</format> <file>error.log</file> <stderr/> </log>

Statistical logging

Statistical log records used for tracking purposes are written to

record.log in the current directory, as determined thus: :

|<log id='rlogger'> <host/> <logtype>record</logtype> <format>%d %h %s</format> <file>record.log</file> </log>

Log records of this type are written when a client connects to the

server and when a client disconnects. Furthermore, we can use the

debugging switch (-D) when we start the server and have debugging and

trace output written to STDERR.

If Your Server Doesn't Start

A number of likely candidates might have prevented your server from starting.

Bad XML configuration

It is not difficult to make errors (typographical or otherwise) in the

server configuration. The first line of defense is to be careful when

editing your jabber.xml file. After that, the Jabber server isn't

going to be too forthcoming with information if you have broken the

well-formedness of the XML: :

| yak:~/jabber-1.4.1$ ./jabberd/jabberd -h yak Configuration parsing using jabber.xml failed

Help is at hand in the shape of Perl and the XML::Parser

module, which is a wrapper around the XML parser, expat. : Providing

you have Perl and the XML::Parser module installed, you can

get expat to give you a clue where the XML is broken: :

|yak:~/jabber-1.4.1$ perl -MXML::Parser -e 'XML::Parser->new->parsefile("jabber.xml", ErrorContext => 3)'

not well-formed (invalid token) at line 47, column 35, byte 1750: be on one line, the server doesn't like it otherwise! :) -->

   <host><jabberd:cmdline
   flag="h"yak</jabberd:cmdline></host>
   ==================================^

   <!-- This is the custom configuration section for the at
   /usr/local/lib/perl5/site_perl/5.6.0/i586-linux/XML/Parser.pm line
   185 yak:~/jabber-1.4.1$

This shows us exactly where the problem is.^[4] In this case, the

close-tag symbol (>) had been inadvertently removed when replacing

localhost with yak.

Unable to listen on port(s)

Taking the standard jabber.xml configuration, the Jabber server tries

to bind to and listen on two ports: 5222 (for client connections) and

5269 (for server-to-server connections). If other processes are

listening to these ports, then the Jabber server can't start and

you'll see something like this in the error log: :

| 20010407T12:11:06: [alert] (-internal): io_select unable to listen on 5222 [(null)] 20010406T12:11:06: [alert] (-internal): io_select unable to listen on 5269 [(null)]}}

 LISTEN

If you see entries like this, it means that processes have been bound

to these ports on all IP addresses.^[5] For example, if 0.0.0.0:5222 is being

listened to then you may have another instance of a Jabber server

already running. : On some BSD systems, you cannot bind to the

"default" null address; the same error messages will be issued as if

the ports were already bound. In the standard jabber.xml configuration

file, a bind to the null address is specified for each port as

standard; you must change this and specify an explicit IP address for

each of the ports in the configuration. That is, instead of: :

|<ip port="5222"/>

do something like this: :

|<ip port="5222">127.0.0.1</ip>