Firewall detects local Port access, but Port hasn't been forwarded by Router

[iceman]

Hi,

I recently got some good help in these groups regarding switch to NAT / Port
Forwarding.

I've setup some Port Forwards for a couple of local services.

However, what I've noticed is that if I watch my Firewall logs (ZoneAlarm),
I can see ZA blocking connection attempts on a UDP port that I haven't
forwarded from my Netgear Router.

My question is, why is this connection attempt being forwarded by the Router
to the laptop behind the router (and on a 192.168 address)? I understood
that attempts to connect to ports that AREN'T forwarded would just be
filtered out by the Router. This looks like it's being passed through to my
laptop.

Am I misunderstanding NAT / Port Forwarding?

Cheers

iceman

 

[Dom]

Please provide more information concerning the nature of the traffic,
especially destination and source IPs and ports.

 

[iceman]

I think it's to do with Azureus. I have configured port forwarding for a
number of Azureus ports (6881 - 6889 UDP).

However, if I watch Zone Alarm alerts and logs, a number of attempts are
made to connect to port 2081 UDP on my 192.168... laptop. I haven't
forwarded 2081 in my Router. There's a variety of source IPs, some using
port 6881.

I can't understand why if the port has not been forwarded from the router,
Zone Alarm can detect connections being made.

The only other port forwarding I've got is a web/ftp server, and netmeeting.

iceman

 

[Dom]

This sounds like response traffic to your own outbound traffic. Do a
netstat -a to see if the laptop is listening for udp on 2081.

 

[iceman]

Thanks for that Dom - I've done an uninstall/reinstall/reboot, and somehow
I'm not getting traffic on this port know.

But I'll keep netstat in mind for the future for other diagnostics.

Thanks again.

iceman