1

I ssh to a Linux server which runs kerberos. This is the first time I met Kerberos.

After some time of being idle or loging out and loging in, I found some strange things, which I am not sure if are created by Kerberos:

  1. I was denied to access my files. When I list these files, I see:

    drwxrwxr-x.  2 tim reg 2048 Apr 10 15:43 doc
    drwxrwxr-x.  2 tim reg 2048 Apr  7 16:59 etc
    ???????????  ? ?    ?     ?            ? README.md
    ???????????  ? ?    ?     ?            ? setup.sh
    
  2. My shell processes running in Screen or Tmux are gone (or killed)

What shall I do to solve the two issues? Thanks!

migrated from serverfault.com Apr 18 '15 at 18:12

This question came from our site for system and network administrators.

2

Kerberos credentials expire after a set amount of time. This is set up by the site admins, typical is about 24hrs.

Your real problem is that your home directory is likely in AFS which is a distributed filesystem that uses kerberos for authentication.

What you need to do to regain file access is to aquire a new kerberos ticket and AFS token. ( tokens are special tickets that live in process space to allow the kernel to access AFS servers on your behalf. )

The exact commands will vary from site to site, but generally

kinit 
aklog

will restore your access to the filesystem. You can find out more about AFS at the OpenAFS website.

OpenAFS Website

  • Thanks. Can we write and run some command/script to automatically renew and extend my credentials? – Tim Apr 18 '15 at 0:47
  • No, you need to type the password to renew credentials. If your site supports renewable tickets you should look for a program called krenew that can keep a ticket alive for up to a month depending on how the kerberos realm is configured. eyrie.org/~eagle/software/kstart/krenew.html – Fred the Magic Wonder Dog Apr 18 '15 at 2:22
  • (1) When shall I run the renew command? If the credential expires in 24 hrs, do I have to run the renew command anytime before it expires? (2) Once I type it, will it expires in a month or just like logging in freshly and expires in another 24 hrs? – Tim Apr 18 '15 at 2:30

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