You may have iptables activated. The default FC3 iptables firewall allows inbound SSH and not much more. The fact that you can get in to the box from the Net shows your routing is OK.
command and see if iptables is running. If the result is anything other than "iptables stopped", then it's running.Code:# service iptables status
You can do some basic modifications to iptables using the lokkit utility. For a more comprehensive iptables tutorial check this link
Hope this helps.