VLF Group compute cluster – Logging in

Logging in

Only nansen is accessible on the network, and only through SSH. Reasons:

Logging in

Only nansen is accessible on the network, and only through SSH. Reasons:

  • Technical: The cluster nodes are connected via an infiniband fabric to the head node. This is a fundamentally different network layer than ethernet, and thus we can’t use bridging, only IP routing. Maintaining our own subnet and router and arranging this with Stanford people is not what we want to be doing.
  • Security: Not using a firewall on the cluster nodes makes MPI, RPC, and general usability a lot easier. Nansen is firewalled externally.
  • Usability: A single point of login helps ensure we all play nicely.

Logging in using X11 forwarding

First install an X server on your machine if you don’t already have one. Ensure your DISPLAY variable is set, and then log in via ssh. From the command line:

  ssh -X username@nansen.stanford.edu

From Putty, you can do the same thing. Run your X server, then under Connection->SSH->X11, check Enable X11 forwarding and set the display location to localhost:0 or localhost:0.0.

Running VNC through an SSH tunnel

First, log in normally through ssh. Then run vncserver:

  [username@nansen torque]$ vncserver
  New 'nansen:3 (username)' desktop is nansen:3
  Starting applications specified in /home/username/.vnc/xstartup
  Log file is /home/username/.vnc/nansen:3.log

You may be prompted to choose a password. Make note of the number (in this case it is 3). Now, we’ll tunnel via ssh:

  ssh -L 5900:nansen:5903 username@nansen

This says that we want to forward connections to the local host at port 5900 to nansen at port 5903 (this is 5900 plus the number 3 above). By convention, VNC connections start at 5900 and are numbered sequentially by their display number, i.e., 0,1,2,…

Now start up a VNC client and connect to localhost:5900, or alternatively localhost at display #0.