Play With a Friend on Garry's Mod?

I was wondering if I could play with a friend on GMod without joining the same server or making a lan server. If I could set up a server on GMod and let my friend join that would be cool, but I can’t. Thanks in advance :smiley:

http://dailydigitaldeals.info/wp-content/uploads/2012/01/11/35/smile.gif

You could use Hamachi or forward port 27015 on your router.