.\" $Revision: 1.5 $
.\"
.TH rwhod++ 8 "05 Feb 1996"
.SH NAME
rwhod++ \- a new rwho daemon
.SH SYNOPSIS
.B rwhod++
[
.B \-d
] [
.BI \-t \ seconds
] [
.BI \-r \ num
] [
.BI \-a \ num
]
.if n .ti +0.5i
.I netgroup
|
.I filename
\&.\|.\|.
.SH DESCRIPTION
.I rwhod++
is a compatible replacement for the classic
.I rwhod
program.
In contrast to
.IR rwhod ,
which is based on broadcasting,
.I rwhod++
polls a list of hosts via RPC and therefore consumes
significantly less network bandwidth.
As
.I rwhod++
actively contacts the specified hosts, the hosts
are not limited to the local network.
The client programs
.RI ( rwhod
and
.IR ruptime )
need not be replaced when the new daemon is used, because
the spool files generated by
.I rwhod++
are identical to those written by the standard
.IR rwhod .
.LP
.I rwhod++
is usually run on a single host in the local network.
The spool directory
.B /usr/spool/rwho
on this host can then be exported via NFS to any number of machines.
However, to avoid byte-order problems and to reduce NFS traffic,
it may be a good idea to periodically cache the
.IR rwho -output
and
.IR ruptime -output
on the system running
.IR rwhod++ ,
and then on all client machines replace
.I rwho
and
.I ruptime
by trivial shell scripts that just
.IR cat (1)
the cache files.
.LP
On startup,
.I rwhod++
reads its arguments to build a list of hosts to contact.
Each argument is either the name of a NIS netgroup or a filename.
Arguments that begin with a slash character (`/') are considered
filenames; each file holds one hostname per line (filenames must be
absolute pathnames so that the files can be reopened once
.I rwhod++
has changed the current directory to
.BR /usr/spool/rwho ).
The final list of hosts is then randomized to eliminate effects caused
by netgroups with their host entries sorted by subnets.
.LP
.I rwhod++
cycles through the list of hosts built on startup, sending one
.I rstat
and one
.I rusers
RPC request to each host during each round.
In the first pass, the hostnames are resolved and the portmapper on
each host is contacted to obtain the port numbers for the RPC calls.
.I rwhod++
collects the RPC replies asynchronously to avoid blocking on
hosts that are not responding.
.LP
If no positive reply is received from a host after a certain number of
requests, the host is
.IR reset .
This causes the hostname to be resolved again and the remote
portmapper to be (re-)contacted during the next round to take care of
hosts that were rebooted or whose IP addresses have changed
since
.I rwhod++
was started.
.SH OPTIONS
.TP
.BR \-t \ seconds
This option specifies the time for one cycle through the list of hosts
contacted by
.IR rwhod++ .
The default is the number of hosts in seconds.
.TP
.BR \-r \ num
.I num
specifies the number of unanswered requests after which the
unresponsive host is reset.
A separate count is maintained for each type of RPC request sent to
each host.
The default value for this option is chosen such that a host is reset
15 minutes after the last successful transaction.
.TP
.BR \-a \ num
.I rwhod++
periodically re-reads its arguments (netgroups and/or files) to check
if any hosts have been added or removed and, if so, updates its list of
hosts.
The option
.B \-a
is used to specify that the arguments should be re-read each
.I num
cycles through the list of hosts.
The default is chosen such that the arguments are re-read once every
half hour.
.I rwhod++
also re-reads its arguments on receipt of a HUP signal.
.TP
.B \-d
Debug mode.
Normally,
.I rwhod++
backgrounds itself on startup and uses
.I syslog
to record error and warning messages.
In debug mode,
.I rwhod++
stays in the foreground and writes messages to standard error output.
.SH EXAMPLES
.LP
.RS
.nf
.B "rwhod++ -t 180 rwhohosts /usr/spool/rwho/etc/extra-hosts"
.fi
.RE
.LP
This command line causes
.I rwhod++
to read hostnames from the netgroup
.B rwhohosts
and, in addition, from the specified file.
Each cycle through the list of hosts will take exactly
three minutes.
.SH FILES
.BR /usr/spool/rwho/whod. *
.SH "SEE ALSO"
.BR ruptime (1),
.BR rwho (1)
.SH AUTHOR
Oliver Laumann, net@informatik.uni-bremen.de