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 5.10							    8 Dec 2001							      in.rwhod(1M)