Super Sparrow: Configuration: Apache on the POP X Router

Configuration: Apache on the POP X Router

Network Diagram
Running Apache
Testing
Starting on System Boot
Configuration Files
Notes on Commands

Network Diagram

Running `named`

One of attractive characteristics of The Apache HTTP Server, is its modular design. This enables a high degree of flexibility in the functionality that is provided. mod_rewrite is a module that ships with Apache that allows URLs to be matched and rewritten. The module allows the map used for rewriting URLs to be an external programme that reads keys from stdin and returns the corresponding value to stdout. By using supersparrow as the external map, Apache can be tied directly into Super Sparrow.

To do, this the configuration files /etc/httpd/conf/access.conf, /etc/httpd/conf/httpd.conf, /etc/httpd/conf/magic and /etc/httpd/conf/srm.conf are used. These configuration files were tested to work with Apache 1.3.12 and are based on those shipping with the apache-1.3.12-2 RPM from Red Hat, Inc.

Of particular note in the configuration file is:

NameVirtualHost 192.168.193.11

<VirtualHost 192.168.193.11>
ServerName www.apache-test.supersparrow
ServerAlias apache-test.supersparrow
DocumentRoot /home/httpd/html/

RewriteEngine on
RewriteLog /var/log/httpd/rewrite_log
RewriteLogLevel 9
RewriteMap ss_map prg:/usr/bin/supersparrow
RewriteRule ^/(.*) http://${ss_map:%{REMOTE_ADDR}}/$1 [R,L]
</VirtualHost>

<VirtualHost 192.168.193.11>
ServerName www.x.apache-test.supersparrow
DocumentRoot /home/httpd/html/
</VirtualHost>

This sets up two virtual services www.apache-test.supersparrow and www.x.apache-test.supersparrow. These are name based virtuals and are both bound to the IP address 192.168.193.11. The RewriteMap line names a map, ss_map that is an external programme, /usr/bin/supersparrow. The following RewriteRule line uses this map to rewrite all URLs to a corresponding URL in either www.x.apache-test.supersparrow or www.x.apache-test.supersparrow depending on the output if /usr/bin/supersparrow.

RewriteLogLevel 9 sets logging of the Rewrite Engine to maximum verbosity, the logs can be found in /var/log/httpd/rewrite_log as per the RewriteLog line. Once the configuration is verified to be working it is suggested that the debugging level be changed to 0, turning logging off. The Apache User's Guide advises against directing the logs to /dev/null as a way of suppressing unwanted messages as Apache has to do additional work to produce the logs. It is best to just turn the logs off instead.

Starting on System Boot

If an RPM was used to install Apache it may be started using its init script. Restart is used as Apache may already be running and it is important that the new configuration files are read.

$ /etc/rc.d/init.d/named start
Shutting down httpd:                       [  OK  ]
Starting httpd:                            [  OK  ]

Otherwise Apache may be stopped and started manually:

killall httpd
/usr/sbin/httpd

To ensure that Apache is started on system boot init needs to run httpd. If Apache was installed from an RPM this should be configured automatically. To verify this use chkconfig.

$ chkconfig --list httpd
httpd           0:off   1:off   2:off   3:on    4:on    5:on    6:off

If httpd is not listed as being on for run-levels 3, 4 and 5 then run the following command. The output from the previous command should then indicate that Apache will run at these run-levels:

$ /sbin/chkconfig --level 345 httpd on
$ /sbin/chkconfig --level 0126 httpd off

If Apache was not installed from an RPM, then you should edit the init scripts in /etc/rc.d/. To ensure that is is run on system boot something along the lines of the following should appear in on of the init scripts. The paths should be modified to match the installation.

if [ -x /usr/sbin/httpd -a -e /etc/httpd/conf/httpd.conf ]; then
  echo Starting httpd
  /usr/sbin/httpd
fi

Testing

To verify that Apache is running use lynx. The following should produce return the root page for your server:

$ lynx -dump http://127.0.0.1/

Configuration Files

For reference the resulting configuration files for Apache are available.

POP X Router: /etc/httpd/conf/access.conf, /etc/httpd/conf/httpd.conf, /etc/httpd/conf/magic, /etc/httpd/conf/srm.conf

A complete set of configuration files for this network setup can be found here.

References

Please see references.

Notes on Commands

Commands shown in paragraphs of preformated text are prefixed by the shell prompt $ to avoid confusion between commands and their output. An instruction to run the command echo flim is formated as:

$ echo flim
flim