I use IP Manager to manage the IP numbers. It’s a very useful program for managing multiple network connections but it is payware. I'm pretty sure they have a trial version you can download. If you want to give it a try and have trouble figuring any aspects out, let me know.
I’ve recently seen reference to the freeware program Mr Plow mentioned,
Pocket Hosts available from the
Handango web site. I haven’t tried it but it does look like it will do what you originally were asking about.