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32 .\" @(#)rwhod.8 8.2 (Berkeley) 12/11/93
40 .Nd system status server
49 is the server which maintains the database used by the
53 programs. Its operation is predicated on the ability to
57 messages on a network.
60 operates as both a producer and consumer of status information,
63 (listen mode) option is specified, in which case
64 it acts as a consumer only.
65 As a producer of information it periodically
66 queries the state of the system and constructs
67 status messages which are broadcasted or multicasted on a network.
68 As a consumer of information, it listens for other
70 servers' status messages, validating them, then recording
71 them in a collection of files located in the directory
76 option enables insecure mode, which causes
78 to ignore the source port on incoming packets.
86 interfaces. This is useful if you do not wish to keep dial on demand
87 interfaces permanently active.
91 option enables listen mode, which causes
93 to not broadcast any information.
94 This allows you to monitor other machines'
96 information, without broadcasting your own.
102 to use IP multicast (instead of
103 broadcast) on all interfaces that have
104 the IFF_MULTICAST flag set in their "ifnet" structs
105 (excluding the loopback interface). The multicast
106 reports are sent with a time-to-live of 1, to prevent
107 forwarding beyond the directly-connected subnet(s).
111 argument is supplied with the
115 will send IP multicast datagrams with a
118 via a SINGLE interface rather
121 must be between 0 and
122 32 (or MAX_MULTICAST_SCOPE). Note that
128 specifies transmission on one interface only.
134 argument, the program accepts multicast
136 reports from all multicast-capable interfaces. If a
138 argument is given, it accepts multicast reports from only one interface, the
139 one on which reports are sent (which may be controlled via the host's routing
140 table). Regardless of the
142 option, the program accepts broadcast or
143 unicast reports from all interfaces. Thus, this program will hear the
144 reports of old, non-multicasting
146 but, if multicasting is used,
149 won't hear the reports generated by this program.
151 The server transmits and receives messages at the port indicated
152 in the ``who'' service specification; see
154 The messages sent and received, are of the form:
155 .Bd -literal -offset indent
157 char out_line[8]; /* tty name */
158 char out_name[8]; /* user id */
159 long out_time; /* time on */
168 char wd_hostname[32];
172 struct outmp we_utmp;
174 } wd_we[1024 / sizeof (struct whoent)];
178 All fields are converted to network byte order prior to
179 transmission. The load averages are as calculated by the
181 program, and represent load averages over the 5, 10, and 15 minute
182 intervals prior to a server's transmission; they are multiplied by 100
183 for representation in an integer. The host name
184 included is that returned by the
186 system call, with any trailing domain name omitted.
187 The array at the end of the message contains information about
188 the users logged in to the sending machine. This information
189 includes the contents of the
191 entry for each non-idle terminal line and a value indicating the
192 time in seconds since a character was last received on the terminal line.
194 Messages received by the
196 server are discarded unless they originated at an
200 option was specified. In addition, if the host's name, as specified
201 in the message, contains any unprintable
204 message is discarded. Valid messages received by
206 are placed in files named
210 These files contain only the most recent message, in the
211 format described above.
213 Status messages are generated approximately once every
219 .Pa /boot/kernel/kernel
220 every 30 minutes to guard against
221 the possibility that this file is not the system
222 image currently operating.
227 Status information should be sent only upon request rather than continuously.
228 People often interpret the server dying
229 or network communication failures
230 as a machine going down.