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RWHOD(8)                FreeBSD System Manager's Manual               RWHOD(8)

NAME
     rwhod -- system status server

SYNOPSIS
     rwhod [-i] [-p] [-l] [-m [ttl]]

DESCRIPTION
     The rwhod utility 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 or multicast messages on a network.

     The rwhod utility operates as both a producer and consumer of status
     information, unless the -l (listen mode) option is specified, in which
     case it acts as a consumer only.  As a producer of information it period-
     ically queries the state of the system and constructs status messages
     which are broadcasted or multicasted on a network.  As a consumer of
     information, it listens for other rwhod servers' status messages, vali-
     dating them, then recording them in a collection of files located in the
     directory /var/rwho.

     The -i option enables insecure mode, which causes rwhod to ignore the
     source port on incoming packets.

     The -p option tells rwhod to ignore all POINTOPOINT interfaces.  This is
     useful if you do not wish to keep dial on demand interfaces permanently
     active.

     The -l option enables listen mode, which causes rwhod to not broadcast
     any information.  This allows you to monitor other machines' rwhod infor-
     mation, without broadcasting your own.

     The -m option causes rwhod to use IP multicast (instead of broadcast) on
     all interfaces that have the IFF_MULTICAST flag set in their "ifnet"
     structs (excluding the loopback interface).  The multicast reports are
     sent with a time-to-live of 1, to prevent forwarding beyond the directly-
     connected subnet(s).

     If the optional ttl argument is supplied with the -m flag, rwhod will
     send IP multicast datagrams with a time-to-live of ttl, via a SINGLE
     interface rather than all interfaces.  ttl must be between 0 and 32 (or
     MAX_MULTICAST_SCOPE).  Note that -m 1 is different from -m, in that -m 1
     specifies transmission on one interface only.

     When -m is used without a ttl argument, the program accepts multicast
     rwhod reports from all multicast-capable interfaces.  If a ttl argument
     is given, it accepts multicast reports from only one interface, the one
     on which reports are sent (which may be controlled via the host's routing
     table).  Regardless of the -m option, the program accepts broadcast or
     unicast reports from all interfaces.  Thus, this program will hear the
     reports of old, non-multicasting rwhods, but, if multicasting is used,
     those old rwhods won't hear the reports generated by this program.

     The server transmits and receives messages at the port indicated in the
     ``who'' service specification; see services(5).  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(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 inte-
     ger.  The host name included is that returned by the gethostname(3) sys-
     tem 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(5) 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 or the -i option was specified.  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/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 /kernel every 30 minutes to guard against the
     possibility that this file is not the system image currently operating.

SEE ALSO
     ruptime(1), rwho(1)

BUGS
     Status information should be sent only upon request rather than continu-
     ously.  People often interpret the server dying or network communication
     failures as a machine going down.

HISTORY
     The rwhod utility appeared in 4.2BSD.

FreeBSD 4.10                   December 11, 1993                  FreeBSD 4.10

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | BUGS | HISTORY

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