Hmm, I suspect the HttpListener class works different on different systems. On my Linux it listens on all interfaces, that may be a Mono bug though. I did look at that code before, but writing your own http server when there is one included in the runtime is just silly and a waste of time in my opinion. What Telemacus does is it lets the connection be configured by an external configuration file. There is a configuration system for plugins in KSP already. There are several other places I have just put arbitrary numbers that should be configurable.