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 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 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 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 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 mul-
ticast 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 attri-
butes:
____________________________________________________________
| 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.
Man(1) output converted with
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