What ports do I open to create a server?

I know that, in order to create a server without a physical server, you need to open 3-4 ports on your router as well as your firewall. I am hesitant to open all of my ports, for security reasons, so I would like to know which 3-4ish ports I need to open. When I say “To create a server” I mean to have the “Create a server” button on Gmod’s main menu to actually work. Also, is there anything else I would need to do? I keep hearing something about using “heartbeat” and sv_lan 0, but those sound like ways to work around opening ports…

I know something similar has been asked, but the search bar yielded very few useful results. Thanks Facepunchers!

[editline]02:09AM[/editline]

Bump of shame

[editline]02:37AM[/editline]

Tried searching again, I got this:
“Sorry, this type of search is disabled until we get a nice fast slave database up and running.”
I really need your help facepunchers!

27015

Forward\open this port and type “clientport 27015” in console…

Uh, in the console? Are you guys SURE I don’t have to open any ports on my router?

You have to OPEN 27015 port, and after creating server via create server in gmod, type “clientport 27015” in gmod console…

Oh, ok, thanks!