How to use Web Based Services on HLRS Compute Platforms

This guide shows you accessing web-based services on HLRS Compute Platforms over SOCKS proxy.

This guide assumes:

• You have access to the Vulcan or Hawk cluster.

Warning: For security reasons;

• Don't start a service on the login nodes, but use services on the compute nodes.
• Only use 127.0.0.1 as the hostname for starting Web based services.
• Otherwise, your service will be accessible by everyone.

Modify your ssh config file

You can use the DynamicForward option with your SSH config (-D parameter if you do not use an SSH config). This will allow you to access local services running on the compute nodes over SOCKS proxy.

• Warning: Exercise caution with wildcards, as they may impact other hosts. Ensure there are no conflicts.

Host vulcan
    Hostname vulcan.hww.hlrs.de
Host n*
    Hostname %h
    ProxyJump vulcan
    SendEnv PBS_JOBID
    DynamicForward 8080
Host hawk
    Hostname hawk.hww.hlrs.de
Host r*
    Hostname %h
    ProxyJump hawk
    SendEnv PBS_JOBID
    DynamicForward 8080
Host hawk-ai*
    Hostname %h
    ProxyJump hawk
    SendEnv PBS_JOBID
    DynamicForward 8080

Create a new Firefox profile

We recommend using Firefox and creating a new profile for accessing the web services running on the compute nodes:

• Open about:profiles, create and launch a new profile.
• In the new profile open about:preferences and search for proxy
• Enter following settings (as shown below):
  • Manual proxy configuration
  • SOCKS Host: 127.0.0.1
  • SOCKS Port: 8080
  • SOCKS v5
  • No proxy for - leave the field empty
  • Proxy DNS

Starting from Firefox v67, you have to do this as well:

• Open about:config
• Find network.proxy.allow_hijacking_localhost and set it to true (Do NOT do this in your default Firefox profile! This may cause security issues when using proxies!)

Firefox proxy settings

Access the web-based service

To use the web-based service, first connect to the compute node running your job from your local computer.

On the login node:

qstat -anw # get the job id and the hostname

On your local computer:

export PBS_JOBID=JOB_ID # e.g., 2316419.hawk-pbs5
ssh COMPUTE_HOST # e.g., hawk-ai08

Check your SSH config in the first step if this doesn't work.

Then, launch Firefox web browser using the new profile. Open 127.0.0.1:PORT_NUMBER to access the service. The PORT_NUMBER is the port number set by the service (not necessarily 8080).