View source for Testing firewall rules with netcat

It's quite easy to test to see if a firewall will allow traffic on a specific port if you have control of the server behind the firewall.  Example:

On the remote side, listen to a port:
<geshi lang="bash">
echo 'OMG!' | nc -l -p 5152
</geshi>

On the local side, use telnet or nc to connect to the remote.

<geshi lang="bash">
telnet remote 5152
Trying 10.136.2.242...
Connected to remote.
Escape character is '^]'.
OMG!
</geshi>

[[Category:Unix]]