[slurm-users] SLURM nodes flap in "Not responding" status when iptables firewall enabled

[Sean Caron]

Hi all,

Does anyone use SLURM in a scenario where there is an iptables firewall on
the compute nodes on the same network it uses to communicate with the SLURM
controller and DBD machine?

I have the very basic situation where ...

1. There is no iptables firewall enabled at all on the SLURM controller/DBD
machine.

2. Compute nodes are set to permit all ports and protocols from the SLURM
controller with a rule like:

-A INPUT -s IP.of.SLURM.controller/32 -j ACCEPT

If I enable this on the compute nodes, they flap up in down in "Not
responding state". If I switch off the firewall on the compute nodes, they
work fine.

When firewall is up on the compute nodes, SLURM controller can ping compute
nodes, no problem. I have no reason to believe all ports and protocols are
not being passed. Time is synched. No trouble accessing slurm.conf on any
of the clients.

Has anyone seen this before? There seems to be very little information
about SLURM's interactions with iptables. I know this is kind of a funky
scenario but regulatory requirements have me needing to tighten down our
cluster network a little bit. Is this like a latency issue, or ...?

Thanks,

Sean
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