rwho

The rwho command produces output similar to who, but for all machines on the local network. If no report has been received from a machine for 11 minutes then rwho assumes the machine is down, and does not report users last known to be logged into that machine.

If a users hasn't typed to the system for a minute or more, then rwho reports this idle time. If a user hasn't typed to the system for an hour or more, then the user will be omitted from the output of rwho unless the -a flag is given.

/var/spool/rwho/whod.*

information about other machines

finger(1), rup(1), ruptime(1), rusers(1), who(1), rwhod(8)

The rwho command appeared in 4.3BSD.

This is unwieldy when the number of machines on the local net is large.