RWHOD(1M)                                               RWHOD(1M)



     NAME
          rwhod - system status server

     SYNOPSIS
          /etc/rwhod

     DESCRIPTION
          Rwhod is the server which maintains the database used by the
          rwho(1C) and ruptime(1C) 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
          /usr/spool/rwho.

          The 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 {
                    structoutmp 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(1) program, and represent load averages over the 5, 10,
          and 15 minute intervals prior to a server's transmission;
          they are multiplied by 100 for representation in an integer.



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     RWHOD(1M)                                               RWHOD(1M)



          The host name included is that returned by the
          gethostname(2) system call, with any trailing domain name
          omitted.  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 in seconds since a character was last
          received on the terminal line.

          Messages received by the rwho server are discarded unless
          they originated at an 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 /usr/spool/rwho.  These files
          contain only the most recent message, in the format
          described above.

          Status messages are generated approximately once every 3
          minutes.  Rwhod performs an nlist(3) on /vmunix every 30
          minutes to guard against the possibility that this file is
          not the system image currently operating.

     SEE ALSO
          rwho(1C), ruptime(1C)

     BUGS
          There should be a way to relay status information between
          networks. Status information should be sent only upon
          request rather than continuously.  People often interpret
          the server dying or network communtication failures as a
          machine going down.

     ORIGIN
          4.3 BSD




















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