We don’t plan to backport this feature, but if the demand is really high, we’ll consider it.
— rkFred Laxton commented
I actually can't believe fail2ban doesn't work with IPv6 on Plesk. I have two servers on 17.5 and one on 17.8, and I cannot upgrade them without a huge risk to my business. Instead at some point I'll provision a new server and put the latest Plesk on it, and migrate *one* server contents to it. So that means it will be more than ONE YEAR from now before I will have IPv6 support on all servers.
Why do I migrate this way? I've been in IT for FORTY YEARS and learned the hard way about upgrade-in-place. Too much can and does go wrong. And it's happened multiple times with me with Plesk over the years. Not doing that.
This way I can test things out for weeks or months until everything is stable and THEN I migrate live clients to it. Works great and no problems.
Except for fail2ban and IPv6.