Port forwarding question

[Vandergraff]

Two family members (one here and one remote) have asked I set up port forwarding so they can play an online multi-player game against each other.

It requires 3 ports to be forwarded (one UDP and two TCP) so the local family member can host a server running the game. So I have forwarded the 3 ports to local PC running game and everyone works fine - the remote family member can log in and the game runs with them both playing.

However I am concerned about the security implications of leaving the 3 ports forwarded. I ran Shields Up test on the 3 ports (when the game was not running) and was surprised to find they were reported as stealth (?) I was expecting them to be reported as open. Is it possible firewall on the local PC is 'stealth'ing these ports or is something else going on? I also ran the pentest-tools.com port tests on these ports - the TCP test sees them a stealthy and the UDP test reports no response (evidently meaning 'open, firewalled or the packet was lost on the way'). Are these ports really stealthy even though they are forwarded.

I was planning to follow Merlin's instructions 'Allow port forwarding to a service only from a specific IP' as the only person who will log in is the remote family member and it seemed this would be more secure. However they don't have a static IP address we would have to monitor in case their IP address changed (they are on Comcast so it doesn't seem to change often).

I'm confused now with these ports apparently being stealthy - are they really? Any other way of checking?

I have an RT-N66 and am running John's fork 374.43_2-11E1j9527

Sorry if its an obvious question - but I am new at this.

 

[RMerlin]

For a remote test to determine if a port is open, there must be a server actively answering connections to that port. When the server is down, there's nobody to answer connection attempts, so the test site receives no replies, and declares them as stealthy.

 

[Vandergraff]

Thanks - that makes sense with your explanation.