Now shows the number of events per time unit, instead of a counter
always increasing until logrotate.
To use journald, set env.logfile to special value 'journald': It will
read the sshd logs from journalctl _COMM=sshd.
To configure the source of journald, set env.journalctlarg:
Example: "env.journalctlarg --unit=sshd.service"
