Time for action – enabling the referer log

By default, there is no referer log. We can enable the referer log using the access_log directive in combination with a custom log format. To generate the referer log, first of all, we need to create a log format as shown:

logformat referer %ts.%03tu %>a %{Referer}>h %ru 

This configuration defines a new log format called referer, which contains a request timestamp, IP address of the client, the referer URL, and the request URL. Now, we need to use the access_log directive with the aforementioned constructed log format as shown:

access_log /opt/squid/var/logs/referer.log referer

Now, let's look at a few lines from the referer log file:

1284576601.898 127.0.0.1 http://en.wikipedia.org/wiki/Main_Page http://en.wikiquote.org/wiki/Main_Page

1284576607.732 127.0.0.1 http://en.wikiquote.org/wiki/Main_Page http://upload.wikimedia.org/wikiquote/en/b/bc/Wiki.png

The referer log is a bit easier to understand. The first column is the time elapsed since epoch...