in.rwhod(1M)						  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 abil-
       ity 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 messages 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 services(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)];
	  };

       All  fields are converted to network byte order prior to transmission.  The load averages are as calculated by the w(1) program, and repre-
       sent 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 information 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  char-
       acter 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 attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWrcmds 		   |
       +-----------------------------+-----------------------------+

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.

SunOS 5.11							    8 Dec 2001							      in.rwhod(1M)