GNU/Linux Desktop Survival Guide
by Graham Williams
Useful tools include ethereal which is a graphical interface to the same output you might get from tcpdump. A typical usage of tcpdump is:
# tcpdump -l -i eth0
-lwill ensure each newly generated line will be output immediately (rather than cached). The
-iidentifies the interface to monitor.
The pktstat package provides terminal top-like view of
network connections. This is useful to provide an instantaneous
summary of network conenctions. The
-F option will expand
hostnames, rather than listing just the first part of a hostname
(without the domain name).