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 ability 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 mes-
sages 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 ser-
vices(4). The messages sent and received are defined in
/usr/include/protocols/rwhod.h and are of the form:
struct outmp {
char outline[8]; /* tty name */
char outname[8]; /* user id */
long outtime; /* time on */
};
struct whod {
char wdvers;
char wdtype;
char wdfill[2];
int wdsendtime;
int wdrecvtime;
char wdhostname[32];
int wdloadav[3];
int wdboottime;
struct whoent {
struct outmp weutmp;
int weidle;
} wdwe[1024 / sizeof (struct whoent)];
};
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System Administration Commands in.rwhod(1M)
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 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 informa-
tion 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 character 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 ASCI 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
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
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System Administration Commands in.rwhod(1M)
ATRIBUTE TYPE ATRIBUTE 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 Last change: 8 Dec 2001 3
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