Manual Pages for UNIX Operating System command usage for man rwhod

System Administration Commands                       in.rwhod(1M)



NAME
     in.rwhod, rwhod - system status server

SYNOPSIS
     /usr/sbin/in.rwhod [-m [ttl]]


DESCRIPTION
     in.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.


     in.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  mes-
     sages  which  are  broadcast or multicast on a network. As a
     consumer of  information,  it  listens  for  other  in.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  ser-
     vices(4). The messages sent  and  received  are  defined  in
     /usr/include/protocols/rwhod.h and 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)];
        };







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System Administration Commands                       in.rwhod(1M)



     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 1, 5, and
     15  minute  intervals prior to a server's transmission.  The
     host name included is that returned by the  uname(2)  system
     call.  The array at the end of the message contains informa-
     tion about the users  who  are  logged  in  to  the  sending
     machine.   This  information  includes  the  contents of the
     utmpx(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  in.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  3
     minutes.

OPTIONS
     The following options are supported:

     -m [ ttl ]    Use the rwho  IP multicast address (224.0.1.3)
                   when  transmitting. Receive announcements both
                   on this  multicast  address  and  on  the   IP
                   broadcast  address.  If   ttl is not specified
                   in.rwhod multicasts on all interfaces but with
                   the   IP TimeToLive set to 1 (that is, packets
                   are not forwarded by  multicast  routers.)  If
                   ttl  is  specified   in.rwhod  only  transmits
                   packets on one interface and setting  the   IP
                   TimeToLive to the specified  ttl.


FILES
     /var/spool/rwho/whod.*    information about other machines


ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:







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System Administration Commands                       in.rwhod(1M)



     _______________________________________________________________
    |       ATTRIBUTE TYPE        |         ATTRIBUTE VALUE        |
    |_____________________________|________________________________|
    | Availability                | service/network/network-servers|
    |_____________________________|________________________________|


SEE ALSO
     ruptime(1), rwho(1), w(1), uname(2), services(4),  utmpx(4),
     attributes(5)

WARNINGS
     This service can cause  network  performance  problems  when
     used  by several hosts on the network. It is not run at most
     sites by default. If used, include the -m multicast option.

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.


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






























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