Specifications

B
Proxy Server: Squid
proxy in the browser. To allow all users to access Squid and thus the In-
ternet, change the entry in the configuration file /etc/squid.conf from
http_access deny all to http_access allow all. However, in doing
so, consider that Squid is made completely accessible to anyone by this ac-
tion. Therefore, you should, in any case, define ACLs to control access to the
proxy. More on this is available in Section B on page 176.
If you have made changes in the configuration file /etc/squid.
conf, instruct Squid to load the changed file. Do this by entering
rcsquid reload or restart Squid with rcsquid restart. Also, the com-
mand rcsquid status is important. With it, determine whether the proxy
is running. With rcsquid stop, halt Squid. The latter can take a while,
since Squid waits up to half a minute (shutdown_lifetime) before drop-
ping the connections to the clients then will write its data to the disk. If
Squid is halted with kill or killall, this can lead to the destruction of
the cache, which will then have to be fully removed to restart Squid.
If Squid dies after a short period of time, although it has seemingly been
started successfully, it can be the result of a faulty name server entry or a
missing /etc/resolv.conf file. The cause of the start failure would then
be logged by Squid in the /var/squid/logs/cache.log file.
If Squid should be loaded automatically when the system boots, reset the en-
try START_SQUID=no to START_SQUID=yes in the /etc/rc.config file.
An uninstall of Squid will neither remove the cache or the log files. Manually
delete the /var/squid directory.
The Configuration File /etc/squid.conf
All Squid proxy server settings are made in the /etc/squid.conf file. To
start Squid for the first time, no changes will be necessary in this file, but
external clients will initially be denied access. The proxy needs to be made
available for the localhost, usually with 3128 as port. The options are ex-
tensive and therefore provided with ample documentation and examples in
the preinstalled /etc/squid.conf file. Nearly all entries begin with a ‘#
’ sign (the lines are commented out) and the relevant specifications can be
found at the end of the file. The given values almost always correlate with
the default values, so removing the comment signs without changing any
of the parameters actually has little effect in most cases. It is better to leave
the sample as it is and reinsert the options along with the modified parame-
ters in the line below. In this way, easily interpret the default values and the
changes.
173SuSE Linux – Firewall on CD2