I've found the simple enclosed perl script useful to use mrtg to graph
traffic through our IP-Filter firewall.  The script may need some
fiddling with the regular expressions to graph what you need at your
site; our if-filter configuration blocks everything on the WAN
interface by default and allows specific protocols in with `pass in
quick' and `block in quick' rules on groups from 100-190; hence the
simple regular expressions.

The usage in mrtg.cfg here is:

# firewall

Target[firewall]: `./fw.pl`

Options[firewall]: growright, noinfo, perhour

MaxBytes[firewall]: 50000

Title[firewall]: IP-Filter

PageTop[firewall]: <center>
		   <h1><font color=red>Firewall Traffic Analysis</font></h1>
                   <h3>Syn/Ack Packets Passed (Connections) on le1 (24.7.4.75)</h3>
		   </center>

YLegend[firewall]: Packets per Hour
ShortLegend[firewall]: pkts/hr
Legend1[firewall]: Inbound connections per hour
Legend2[firewall]: Outbound connections per hour

--

Ronald Florence			http://members.home.net/18james