Server Ports

Hello. I have looked through alot of the Posts and I didn’t find anything on how to change your server’s Port. I only want it set to a certain one that I chose. does it have to be 27015 or w/e. I really would like to change it. And I really would not like to have to go into my port forwarding and change it… I am only allowed one port to be open. -.-

Start srcds and add “-port $desired port #” to the start line.
srcds.exe -console -game garrysmod -maxplayers 8 -port 27020 +map gm_construct

Thanks