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RedHat 9 (Linux i386) - man page for rwhod (redhat section 8)

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

NAME
     rwhod -- system status server

SYNOPSIS
     rwhod [-bpa] [-u user]

DESCRIPTION
     Rwhod is the server which maintains the database used by the rwho(1) and ruptime(1) pro-
     grams.  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 /var/spool/rwho.

     The server transmits and receives messages at the port indicated in the ``rwho'' service
     specification; see services(5).

     If the -b flag is supplied, only broadcast interfaces, such as ethernets, will be used.  If
     the -p flag is supplied, only point-to-point interfaces will be used. If the -a flag is sup-
     plied, or no flags are supplied, all interfaces will be used.

     If the -u flag is supplied, rwhod will run as the specified user instead of as root.

     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(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(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.  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/spool/rwho.	These files con-
     tain only the most recent message, in the format described above.

     Status messages are generated approximately once every 3 minutes.	Rwhod recomputes the sys-
     tem boot time every 30 minutes because on some (non-Linux) systems it is not a totally reli-
     able process.

SEE ALSO
     rwho(1), ruptime(1)

BUGS
     There should be a way to relay status information between networks.  People often interpret
     the server dying or network communtication failures as a machine going down.

HISTORY
     The rwhod command appeared in 4.2BSD.

Linux NetKit (0.17)			   May 13, 1997 		      Linux NetKit (0.17)


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