If you are running Overseerr behind a reverse proxy, make sure that the Enable Proxy Support setting is enabled.
To use Fail2ban with Overseerr, create a new file named
overseerr.localin your Fail2ban
filter.ddirectory with the following filter definition:
failregex = .*\[warn\]\[API\]\: Failed sign-in attempt.*"ip":"<HOST>"
You can then add a jail using this filter in
jail.local. Please see the Fail2ban documentation for details on how to configure the jail.