Netcat echo mode

[ml at bortal.de]

Hello,

i would like to send some data from a netcat client to a netcat server.
Can you set up the netcat server so that it echos what he recieves?

Background: I would like to test my firewall setup if all my open ports
(tcp and udp) work. So i want to send some data and check if the same
data comes back.

Can netcat do that? (no i dont want to use nmap :) )

Thanks, Mario