IPCop is a great firewall distro that you can have up and running within minutes, but there are a few really useful bits missing. No sysadmin's day is complete without the words "why is the internet so slow" being uttered by one of the flock - now you can answer with a smile and find the bugger who is slowing it all down...
iftop gives a real-time view of what is crossing your ipcop's nic (default eth0) - and to get it all you need to do is update to the latest version. Enable ssh access, and log in as root on port 222, then just run iftop (you can run iftop -i ethX for a different nic as well). This shows a nice real time summary of what is going on, with the big spenders at the top, including traffic source, destination and direction. A nice quick way of seeing if there is anything big going through your gateway.
