RE: netfilter: iptables-restore: setsockopt(3, SOL_IP, IPT_SO_SET_REPLACE, "security...", ...) return -EAGAIN

From: Dexuan Cui
Sent: Wednesday, May 12, 2021 11:02 PM

BTW, I found a similar report in 2019:

"
https://serverfault.com/questions/101022/error-applying-iptables-rules-using-iptables-restore
I stumbled upon this issue on Ubuntu 18.04. The netfilter-persistent
service failed randomly on boot while working ok when launched manually.
Turned out it was conflicting with sshguard service due to systemd trying
to load everything in parallel. What helped is to setting
ENABLE_FIREWALL=0 in /etc/default/sshguard and then adding sshguard chain
and rule manually to /etc/iptables/rules.v4 and /etc/iptables/rules.v6.
"

The above report provided a workaround. 
I think we need a real fix.

Thanks,
-- Dexuan