For the record I struggled a lot with the npf(4) configuration breaking before this even worked.

This is how I currently have configured the (in)famous fail2ban at laidback.moe:

jail.local
```
[DEFAULT]
action = npf
bantime = 604800
maxretry = 3

[sshd]
enabled = true
[dovecot]
enabled = true
[postfix]
enabled = true
```

npf.conf
```
table <fail2ban> type ipset
```

---

You have kept hitting my nerves for so long, and I'm done with you.
Prepare for the worst.

That is all.