Not sure why the other recent thread about Source 2007 was locked, but I was trying to set up a server on Linux and couldn't get it to connect to the Steam servers. Eventually figured out that you need to have a Steam client open while launching the server for it to connect, but it needs to be the Windows version of Steam installed and launched with Wine. You also need to be using the Windows version of the Source 2007 Dedicated Server with Wine as well. After that it would connect every time.

Probably not too many people hosting games for Source 2007 anymore but just wanted to post it here in case anyone else ends up having the same problem.