Ssh – /run/user/$UID not created

pamsshsystemd

I have a cluster where users login via ssh to the head node. On the head node /run/user/$UID directories are created via pam_systemd.so, as expected. Subsequently, users can then log into a compute node, again via ssh. On the compute node, however, /run/user/$UID directories are not created (except for one for root), although the systemd-logind service is running.

Any ideas what the problem might be?

Best Answer

My description of the situation was inaccurate. In fact the user was not logging into the compute node via ssh but using Slurm's srun command to start a remote shell. This command allocates resources and performs the authentication via munge and apparently sidesteps PAM. If, however, the user just reserves resources via salloc and then uses ssh to log into the allocated compute node, then PAM kicks in and /run/user/$UID is created, as expected.

Related Solutions

SSH – How to Recover from ‘Too Many Authentication Failures for User Root’

Are you sure that root login to ssh is allowed?

Check sshd_config and verify that root login is permitted. sshd will need to be restarted if the setting changes.

Ssh – pam_tally2 or pam_faillock account lockout with ssh

If you enable PasswordAuthentication then the SSH daemon handles passwords itself and not using PAM. You actually want to disable this in order to force it to use PAM:

PasswordAuthentication no
UsePAM yes
ChallengeResponseAuthentication yes

That won't catch users using keys however (although personally I think that's fine). If you do you'll probably have to use something like fail2ban which looks for authentication failures in the logs and adds iptables rules to block future attempts.

Best Answer

Related Solutions

SSH – How to Recover from ‘Too Many Authentication Failures for User Root’

Ssh – pam_tally2 or pam_faillock account lockout with ssh

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