rwhod(1M)                        (TCP/IP)                         rwhod(1M)


   NAME
         rwhod, in.rwhod - system status server

   SYNOPSIS
         in.rwhod

   DESCRIPTION
         rwhod is the server which maintains the database used by the rwho(1)
         and ruptime(1) programs.  Its operation is predicated on the ability
         to broadcast messages on a network.

         rwhod operates as both a producer and consumer of status information.
         As a producer of information it periodically queries the state of the
         system and constructs status messages which are broadcast on a
         network.  As a consumer of information, it listens for other rwhod
         servers' status messages, validating them, then recording them in a
         collection of files located in the directory /var/spool/rwho.

         The rwho server transmits and receives messages at the port indicated
         in the rwho service specification, see services(4).  The messages
         sent and received, are of the form:
               struct      outmp {
                     char  outline[8];      /* tty name */
                     char  outname[8];      /* user id */
                     long  outtime;   /* time on */
               };

               struct      whod {
                     char  wdvers;
                     char  wdtype;
                     char  wdfill[2];
                     int   wdsendtime;
                     int   wdrecvtime;
                     char  wdhostname[32];
                     int   wdloadav[3];
                     int   wdboottime;
                           struct      whoent {
                           struct      outmp weutmp;
                           int   weidle;
                     } wdwe[1024 / sizeof (struct whoent)];
               };

         All fields are converted to network byte order prior to transmission.
         The load averages are as calculated by the w(1) program, and
         represent load averages over the 5, 10, and 15 minute intervals prior
         to a server's transmission.  The host name included is that returned
         by the gethostname(2) system call.  The array at the end of the
         message contains information about the users logged in to the sending
         machine.  This information includes the contents of the utmp(4) entry
         for each non-idle terminal line and a value indicating the time since
         a character was last received on the terminal line.


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   rwhod(1M)                        (TCP/IP)                         rwhod(1M)


         Messages received by the rwho server are discarded unless they
         originated at a rwho server's port.  In addition, if the host's name,
         as specified in the message, contains any unprintable ASCII
         characters, the message is discarded.  Valid messages received by
         rwhod are placed in files named whod.hostname in the directory
         /var/spool/rwho.  These files contain only the most recent message,
         in the format described above.

         Status messages are generated approximately once every 60 seconds.
         rwhod performs an nlist(3) on /stand/unix every 10 minutes to guard
         against the possibility that this file is not the system image
         currently operating.

   FILES
         /var/spool/rwho

   SEE ALSO
         rwho(1), ruptime(1), w(1), gethostname(3), nlist(3), utmp(4).

   NOTES
         This service takes up progressively more network bandwidth as the
         number of hosts on the local net increases.  For large networks, the
         cost becomes prohibitive.

         rwhod should relay status information between networks.  People often
         interpret the server dying as a machine going down.



























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