Port Forward

[Gaz_]

So i'm familiar with port forwarding, and generally have no real issues, however ive run into one where a certain port is not open. Its under the same rule in a BT HH3 with another 5 which are all open. Its a UDP port.

Does the address i forward to have to be "listening" for this port to show open? ie does something have to be behind this open port to show its open? Its something ive always wondered but never known...

Its a remote site and telent shows it closed

 

[DannyR]

Try canyouseeme.org and see if you can see it?

The address your forwarding too will be listening as such so will always be able to see traffic coming in that port.

 

[mgd]

If it's udp port you will not get a response via telnet, nmap will help you test if it's open or not.

 

[Gaz_]

so just nmap bang in the address use the -sU command?
What range does it scan? I'm looking for quite high numbers, but cant see where i can filter the search?

fecking udp, pain in the hoop!

Basically got a site that was all fine on a HH3, then the router locked up/crashed about 4 months later. reboot, all seemed well. tcp ports showing open, but For some reason this UDP port is still closed (cant connect audio to the unit on site) yet the rules are as before.