Netstat syntax

tekmann33 · 03-06-2008, 01:55 PM

I understand how netstat can be used to show used ports on a particular machine, but how would one use it to show used ports for an entire network?

To be more specific, I am configuring a proxy server and I want to use a port that is not used by the network, so I need a list of ports that are already in use.

Tinkster · 03-06-2008, 02:23 PM

In brief: you can't.

Netstat will only display port/ip pairs for a) listening processes on
the machine it's invoked on or b) for established connections to the
machine it's invoked on.

To find all ports in use (unless of course stealthed by some firewall
product) you want to use nmap or some other port-scanner. Before you
do so make sure you're not in violation of any corporate policy.

Cheers,
Tink