rwhod(1M)                                                  rwhod(1M)


       NAME
             rwhod - system status server

       SYNOPSIS
             in.rwhod

       DESCRIPTION
             The rwhod command 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  out_line[8];      /* tty name */
                         char  out_name[8];      /* user id */
                         long  out_time;   /* time on */
                   };
                   struct      whod {
                         char  wd_vers;
                         char  wd_type;
                         char  wd_fill[2];
                         int   wd_sendtime;
                         int   wd_recvtime;
                         char  wd_hostname[32];
                         int   wd_loadav[3];
                         int   wd_boottime;
                         struct      whoent {
                               struct      outmp we_utmp;
                               int   we_idle;
                         } wd_we[1024 / sizeof (struct whoent)];
                   };

             All fields are converted to network byte order prior to
             transmission.  The load averages are as calculated by the
             w(1BSD) program, and represent load averages over the 5, 10,
             and 15 minute intervals prior to a server's transmission.  The


                           Copyright 1994 Novell, Inc.               Page 1

      rwhod(1M)                                                  rwhod(1M)


            host name included is that returned by the gethostname(3BSD)
            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.

            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(3E) 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

      USAGE
            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.

            No updates will be sent through ignored network interfaces
            specified in /etc/inet/if.ignore.

         Warnings
            For rwhod to work properly, the directory /var/spool/rwho must
            be created by the system administrator.  Given the adverse
            effect rwho can have on system and network performance, the
            system administrator must decide whether the benefits of the
            rwho feature are worth the performance cost.

      REFERENCES
            gethostname(3BSD), nlist(3E), ruptime(1), rwho(1), utmp(4),
            w(1BSD)

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


                          Copyright 1994 Novell, Inc.               Page 2

       rwhod(1M)                                                  rwhod(1M)


             down.















































                           Copyright 1994 Novell, Inc.               Page 3