Access to Linux and macOS systems from outside

X-Window graphics with Linux or macOS

If you are a Linux or macOS user at home and want to use graphical X applications (e.g. Mathematica or Matlab) on a computer in the HZB intranet, you have little trouble. Both systems use the X Window System directly. For macOS you have to install the X server once from the appstore (package XQuartz).

Your own X-Server on your computer is connected to the application (the X-Client) via a tunnel through the access computer display.helmholtz-berlin.de.

To do this, log on to the access computer from your PC in a terminal window with ssh:

ssh -X xyz@display.helmholtz-berlin.de

xyz is your HZB identification with the external password.

With the command ssh you can now go to the HPC cluster computer dirac-meister. The DISPLAY variable in your shell is automatically set correctly, please do not change it. The X in -X is capitalized and tells ssh to forward X automatically.

ssh -X dirac-meister

Now start an X-application, e.g. xterm  and you will see the output on your PC:

xterm

To copy files from the home directory in HZB to the Linux PC at home, the first ssh connection is modified:

ssh -X -L 2222:dinux4:22 xyz@display.helmholtz-berlin.de

You can choose the port number 2222 in the range 1024-65535.
After that you can call in a local shell on your home PC

scp -P 2222 localhost:a.txt

to fetch the file a.txt from the home directory. scp will ask you the first time if you want to accept localhost:2222