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NetBSD 6.1.5 - man page for rwhod (netbsd section 8)

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

NAME
     rwhod -- system status server

SYNOPSIS
     rwhod [-i interval] [-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.

     The following options are available:

     -i interval  Allows for the broadcast interval to be changed from the default 3 minutes.
		  The interval argument is the number of seconds to change the interval to, or if
		  the value is suffixed by ``m'' then it is interpreted as minutes.  The maximum
		  allowed value for the broadcast interval is 11 minutes because higher values
		  will cause ruptime(1) to mark the host as being down.

     -u user	  Drop privileges and become the user user.

     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/rwho.

     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 */
		   int32_t out_time;		   /* time on */
	   };

	   struct  whod {
		   char    wd_vers;
		   char    wd_type;
		   char    wd_fill[2];
		   int32_t wd_sendtime;
		   int32_t wd_recvtime;
		   char    wd_hostname[32];
		   int32_t wd_loadav[3];
		   int32_t wd_boottime;
		   struct  whoent {
			   struct  outmp we_utmp;
			   int32_t 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) function call,
     with any trailing domain name omitted.  The array at the end of the message contains infor-
     mation about the users logged in to the sending machine.  This information includes the con-
     tents 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(1) server are discarded unless they originated at an rwho(1)
     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/rwho.  These files contain
     only the most recent message, in the format described above.

     Status messages are generated by default approximately once every 3 minutes.

SEE ALSO
     ruptime(1), rwho(1)

HISTORY
     The rwhod command appeared in 4.2BSD.

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 communication failures as a machine going down.

BSD					September 12, 2005				      BSD
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