how to open TCP/UDP ports through NT firewall in .NET 3.5

Another way to do this is to use the netsh command. You would launch it as a process using Process.Start. This works on XP and Windows 7 (I assume Vista also because it works on 7).

 For example, if you wanted to open UDP port 20502, the netsh command would be:

 netsh firewall add portopening UDP 20502 UserFriendlyName ENABLE ALL

 And, if you wanted to close the port:

netsh firewall delete portopening UDP 20502 ALL

If you want to add a program exception to the firewall:

netsh firewall add allowedprogram "c:\program files\your folder\your.exe" UserFriendlyName

If you want to remove a program exception from the firewall: 

netsh firewall delete allowedprogram "c:\program files\your folder\your.exe"