Oidentd fails to work when started by systemd .socket listener

[Sander Smeenk]

At least in Ubuntu 22.04, possibly earlier, oidentd is started by systemd acting as an inetd. This no longer works in 22.04 because of options set in the `.service` file and fed to oidentd at startup.

This looks to be a mix of the systemd `Standard[In|Out]put=..` settings and startup options for oidentd. Oidentd (in the default `-I` mode) expects to have the client on stdin/stdout. Systemd foils that by redirecting StandardOutput to journal or syslog.

I changed my `/lib/systemd/system/oidentd@.service` to have:

  StandardInput=socket
  StandardOutput=socket

And i have removed the `-S` option to oidentd from the `ExecStart` line.

It now works fine for me. Logs end up in syslog and most important, ident works again.