Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
RWHOD(8)                FreeBSD System Manager's Manual               RWHOD(8)

     rwhod - system status server

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

     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 or multicast messages on a network.

     Rwhod 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 periodically 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, validating them,
     then recording them in a collection of files located in the directory

     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

     The -l option enables listen mode, which causes rwhod to not broadcast
     any information.  This allows you to monitor other machines' rwhod
     information, 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
     integer.  The host name included is that returned by the gethostname(3)
     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(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

     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.

     ruptime(1), rwho(1)

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

     The rwhod command appeared in 4.2BSD.

FreeBSD 11.0-PRERELEASE        December 11, 1993       FreeBSD 11.0-PRERELEASE


Want to link to this manual page? Use this URL:

home | help