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Linux and Mac Troubleshooting

Troubleshooting login problems for Linux and Mac machines.

In order to log in to PDC computers you require

  1. A Kerberos installation
  2. A SSH implementation that supports Kerberos.

Logging into PDC is a two stage process. You must firstly generate Kerberos credentials using kinit (which requires a password) then use those credentials together with SSH to log in (which does NOT require a password).

Firstly make sure you have followed the instructions for your operating system or Linux flavour.

Problems with kinit

To generate kerberos credentials you should use

kinit -f username@NADA.KTH.SE


kinit --forwardable username@NADA.KTH.SE

Note that the case is important, so it is NADA.KTH.SE not

More information on possible errors.

Problems with SSH


ssh -o GSSAPIDelegateCredentials=yes -o GSSAPIKeyExchange=yes \

-o GSSAPIAuthentication=yes

and look at the error messages you receive.

If you can log in setting the relavant options explicitly but it fails if you do not then probably you have set your .ssh/config file incorrectly. More information on setting up .ssh/config file.

We have a list of possible error messages and possible causes.

Contacting Support

If after reading this page and the instructions for your operating system carefully you still cannot log in please contact support with the following information

  • Username
  • Which operating system and version you are using (e.g. openSUSE 12.1)
  • Any output/error message you got from
  • kinit -f username@NADA.KTH.SE
  • The output from
  • klist -f
  • The output from
ssh -vv  -o GSSAPIDelegateCredentials=yes -o GSSAPIKeyExchange=yes \

-o GSSAPIAuthentication=yes

Note the extra -vv option adds a lot of output which can be useful to diagnose exactly what is going on.