Identifying what's opening a port

[Radiator]

Just installed Win7 and noticed that the machine IP opens a UDP port on my router and I was wondering how to find out which program is doing it.

 

[jdabbs]

Netstat -b will display the process associated with a connection on your PC, but you must still correlate it with what is shown on the router.

Edit: Oh yeah, UDP: no connection. I'd work backwards, googling the port number for a list of candidate programs (there is often just one), then check the PC for a match.

 

[stevech]

On your router, disable universal plug-n-play and PCs will not be able to alter router settings automatically. You can close the UDP port using the router's admin.

I cannot think of a reason a PC needs to open a UDP port. And with UDP, there must be a corresponding port-forwarding setting to route incoming UDP packets to a specific LAN IP address which, if DHCP, will change anyway.

A game might setup port-triggering. A VoIP ATA device might want a port opened. An IP camera might need such.

Normally, routers don't block outgoing UDP, only incoming, unless there's a port-forwarding rule for UDP on a given port number for a certain LAN IP address.