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Helpdesk : AFS

These are frequently asked about AFS, that might help you resolve your problem. If you cannot find an answer to your question here, or in the guided tours, then use the report form and we will try to assist you as soon as possible.


Why can't I access the AFS filesystem?


Usually you authenticate yourself when you login to a PDC machine. The only exception is when you login from a machine in another Kerberos realm (site where Kerberos is used) that is "known" by the PDC Kerberos.
As a side effect of this authentication you will get what is called a Kerberos ticket and an AFS token. The kerberos ticket is used (automatically, you dont have to do anything) to request services like the right to rlogin to another machine without password, the right to retrieve mail from the mail server, etc. The AFS token is needed to get access to the file system. In some circumstances these functions don't seem to work. Let's examine some common problems:

  • You cannot read/write files in your home directory anymore
    This is typically caused by tokens expiring and it is necessary to renew them. This is done with the command kauth.
  • No write access after rlogin to another PDC machine
    This happens because rlogin doesn't propagate tickets or tokens to the remote machine. Assume your keyboard is connected to a machine called `workplace' and our machine called strindberg. You should first give yourself a ticket on the machine you want to rlogin to (strindberg in this case) like this
    • workplace>kauth -h strindberg.pdc.kth.se
      -n your-username-at-pdc@NADA.KTH.SE
    and then get AFS tokens on the remote machine like this
    • strindberg> afslog
    You can list your tickets and tokens with the commands
    • strindberg> klist
    • strindberg> tokens


Can I authenticate to AFS at PDC from another site?


Yes, but it isn't automatic. Please get in touch with us is this is of interest to you. Note that this is of interest only if the other site has AFS installed. Some do, but most don't, because AFS usually costs money, however...

Note that you do not need to have AFS installed at your site to use the computers at PDC.


How do I extend tickets or tokens for my batch job?


If you run Easy the tokens for AFS are copied out of the kernel, where they are stored, and saved into a file at submit time . You can not extend the lifetime of the tickets/tokens of a job when it is already submitted! You can read about how to create tickets with long lifetimes at the Kerberos Guided Tour.


Other problem


If you couldn't find your problem listed above, you can fill out this form describing your problem in detail, and we will try to address it as soon as possible.


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