I'm not sure whether this is a Windows problem or a .NET problem (i.e. whether it belongs here on on SO), but I've written a small HTTP server program in C# (using the .NET HttpListner class) which works fine for the most part, but Windows Firewall seems to be refusing to let connections through to it from anything other than localhost. I've added exceptions for TCP and UDP in the "Inbound Rules" section of the firewall settings, essentially duplicating existing rules for other HTTP-based services which work fine (e.g. foo_httpcontrol). Specifically, I've added separate rules for TCP and UDP connections covering all ports, specific to the executable I'm running.

There's no problem when Windows Firewall is disabled, but if I enable it, the connection simply times out.