firewall on ubuntu 9.04

[alin19]

hello again;

i'm trying to run some programs that uses a connection
if i try to initiate from my computer the connection, it works, but if somebody from another location try to connect to my computer it can't

i think it has something about the firewall , how can i set what aplications to be able to recive connection from the internet?

thanks


L.E.

i have find out about ufw and how to add rules to allow connections but how can i find out on with port the aplication is trying to connect?