Here is the situation. I run all my internet through a vpn service, but I have one program that needs a forwarded port. Port forwarding is possible with my vpn but it is a pain because it needs to be reset every hour and the port changes every time.
So I came up with this idea and wanted to see if it would work. Have the ethernet port on my MB run the vpn and all my internet as usual. Shove an old ethernet card I have in and set it up without the vpn. Will that work?
The program is run from the command line and runs constantly. How would I get it to use the second connection (ETH1 I'm guessing). Would it be easier to run it as another user with only that connection enabled? Will switching to TTY1 (ctrl-alt-F1), starting it up as another user, and switching back work? does switching back and forth suspend the other or do they continue in the background?

I know its a unusual situation, but I'm hoping someone here will be able to help.