Issue Latest update froze my servers

[manipogo]

Server operating system version

RockyLinux 8

Plesk version and microupdate number

18.0.51 Update #1

The plesk update from this morning locked up two of my servers and a reboot was required to get them back online. The two servers in question were running RockyLinux 8 and Plesk 18.0.51 Update #1. I had two other servers running Centos 7 and the same update was applied. They were not effected. The monitoring log shows CPU usage sustained in high gear for the duration of time that it was locked up.

I am trying to trace the issue and prevent future problems.

One possible cause is that Port 53 (DNS) was closed to incoming traffic on the new servers. I thought since I wasn't running DNS I didn't need to have ports open for incoming traffic and up until now it didn't cause any issues. But after the update I could no longer use dig. Could Plesk have locked up trying to phone home after the update?

After the reboot I also had to rebuild my apache configuration file on one of the new servers. It only had one active site, which was a staging subdomain. I also couldn't connect to the staging site until I assigned it a Let's Encrypt cert. The default cert refused to connect. This wasn't the case before the update.

Anyone else have these issues? Any ideas on how I can trace this problem?

Thanks

 

[JohnBee]

A recent Plesk update also froze my server, forcing me to reset as well.
Thankfully, I was able to catch it sooner than later, and it was at a time where my server activity was at a bare minimum, and so no harm done.

 

[Peter Debik]

@JohnBee Did you find the cause?

 

[JohnBee]

I did not - there was nothing in the logs or otherwise to explain the service interruption.
My VPS control panel identified the server as 'online', though I was not able to ping the server locally - I restarted and everything was back to normal

 

[manipogo]

@Peter Debik It appears that the issue for me was related to the Plesk firewall. After the updates, the iptables file was inexplicably changed to block all traffic. This happened a few times. I have disabled Plesk firewall and this is no longer happening.

 

[Peter Debik]

@manipogo This sounds as if Fail2Ban has listed your server's IP address. Please make sure that your local IPv4 and IPV6 addresses are whitelisted in Fail2Ban.

 

[Dave W]

Is firewalld installed?