I am running fail2ban since November 2017 and all unsuccessful attempts to log-in to sshd are monitored. Breaking down these attempts according country shows that Chinese IP addresses are coming first here.
The numbers are:
13589 United States
2157 Russian Federation
The distribution of total attacks per month is as depicted below:
Recently one node was changed from octacore to hexacore. Since that time
sinfo showed this node in STATE drain. Stopping and restarting
slurmctld did not resolve the issue. Log file
[2019-12-31T23:57:52.588] error: Node X appears to have a different slurm.conf than the slurmctld. This could cause issues with communication and functionality. Please review both files and make sure they are the same. If this is expected ignore, and set DebugFlags=NO_CONF_HASH in your slurm.conf.
This hinted that some caching is the culprit. Entry
slurmctld stores state. Removing the files in that directory and restarting
slurmctld solves the problem.