1. First make sure the X11 app is installed on your Mac. Locate the X11 app using Finder -> Applications -> Utilities -> X11.app , and launch it. If it is the first time, it will install the X11 framework on your MacOS. Once installed, it will simply start the X11 application. If it is started, locate the “X” icon on the taskbar, and quit it.
2. If you need to VPN/FRAC etc. into any remote network, do that first. Any change in IP address later will cause the X11 framework to be confused (without being too technical).
3. ssh into the remote server using the command below. Note, the -C -o CompressionLevel=9 will cause the data to be compressed before shipping it across the network. This will help for slow data connections, but hurt if the remote or local machines are not fast enough.
ssh -Y -C -o CompressionLevel=9 -l <username> <remote_ip_address>
4. Once logged in the remote server, execute the command “xlogo” to launch a light X application that would just display a “Xlogo” on your computer. When you launch this, it should automatically start the X11 (or XQuartz) application on your MacOS, before displaying the window. If you see the window, it means all is working well. If not, then check your DISPLAY variable. It should be set to something like “localhost:nn.0″ – where nn is some number.