How to open TCP port in connection to ip-address?

[Growmore]

How do i open a TCP port in connection to specific IP-adresses?
Is this done differently depending on the firewall?

A friend asked me to help him and i'm not sure of what firewall he has(he didn't know xD), but i'll post it when i find out.

Thanks

 

[scaye]

Probably the firewall in the router. Normally you just would use *port forwarding* to allow a certain IP access to a certain port.