2.11BSD#431 - /usr/man/cat8/rwhod.0

RWHOD(8)	    UNIX Programmer's Manual		 RWHOD(8)


NAME
     rwhod - system status server

SYNOPSIS
     /usr/sbin/rwhod

DESCRIPTION
     Rwhod is the server which maintains the database used by the
     rwho(1) and ruptime(1) programs.  Its operation is predi-
     cated 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 mes-
     sages which are broadcast on a network.  As a consumer of
     information, it listens for other rwhod servers' status mes-
     sages, 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 indi-
     cated in the ``rwho'' service specification; see ser-
     vices(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 {
	       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.
     The host name included is that returned by the gethost-
     name(2) system call, with any trailing domain name omitted.
     The array at the end of the message contains information


Printed 11/26/99	November 16, 1996			1


RWHOD(8)	    UNIX Programmer's Manual		 RWHOD(8)


     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 termi-
     nal 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(1), ruptime(1)

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.


Printed 11/26/99	November 16, 1996			2