Full-featured traffic analyzers for Linux systems such as ntop and vnstat are widely available, but sometimes you just want a simple program that gives you fast, basic information about the amount of traffic going in and out of the hosts on your network. Darkstat, a packet sniffer that runs as a background process, fills that role. It gathers statistics about network usage and displays them over HTTP.
I tested the latest version (darkstat-3.0.707.tar.bz2) on CentOS 5 and Fedora 7 systems. You can untar this file with
tar-xvjf darkstat-3.0.707.tar.bz2, then install it with the usual
./configure; make; make install. To invoke darkstat, enter: