To be exact – how to monitor web browsing usage.

Answer: use squid + sarg
You can see its sample reports here. Quite nice indeed.

I’m delighted to found that it’s very easy to setup in FC3. Just follow these steps:

• Install Squid: yum install squid
• Download sarg: wget http://www.mack.ro/linux/sarg/sarg-2.0.9-2.fc3.mack.i386.rpm
• Install sarg: rpm -ihv sarg-2.0.9-2.fc3.mack.i386.rpm
• Configure squid.
  At minimum, here’s what you’ll need to do:
  1. Edit /etc/squid/squid.conf
  2. Find http_access allow localhost
  3. Replace that line with these:
     
     acl our_networks src 192.168.10.0/24 localhost
     http_access allow our_networks
     
  4. Put this line: visible_hostname [your_server’s_hostname]
     (your server’s hostname can be found out by typing hostname)
  5. I’m quite sure that’s the minimum that you need to do before you can run squid, but I’m typing this from my memory, so please feel free to correct any mistake.
• Set squid to be automatically run everytime the server starts: chkconfig squid on
• Run squid now: service squid start
• Now set the users’ browser to use squid. Point its proxy server setting to squid server’s IP address, and port 3128.
• After a while, the data will start to accumulate in squid’s logs. To process them, type: sarg
  This takes a while, because the reports it produces are quite comprehensive.
• To view the report from the server where sarg was run, type: links /var/www/sarg/ONE-SHOT/index.html
  (or substitute links with lynx if that’s what you got)

Enjoy.