Re: Interesting Ethernet/UNIX 4.2 observation.

Chris Torek (
Sun, 23 Feb 86 23:22:24 EST

Unix does not broadcast rwho requests; rwho runs entirely locally.
Rwhod *must* send updates in order to allow downtime determination
at remote sites (though if all you are interested in is load average
and users, sending updates makes little sense). In addition, there
is no easy way to determine who really *is* interested in the
information; the problem is quite similar to that of determining
to whom to send routing information. The obvious easy answer is
to use broadcasts (on networks that support the concept).

In 4.3, rwhod sends broadcasts only once every two minutes. If
this is still too much for your network, why are you running it at
all? And if you are running it because it is more useful than it
is expensive, why are you complaining? If you know how to make it
work better, change it!

This is not intended as flamage. I am entirely serious: if it is
broken, fix it; if it is useless, do not use it; but please do not
simply complain that Unix is flawed because rwho uses broadcasts.
It comes configured that way only because those who make the tapes
find it more useful than costly. It is quite simple to turn off.


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