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32 .\" @(#)rwhod.8 8.2 (Berkeley) 12/11/93
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41 .Nd system status server
51 utility is the server which maintains the database used by the
55 programs. Its operation is predicated on the ability to
59 messages on a network.
63 utility operates as both a producer and consumer of status information,
66 (listen mode) option is specified, in which case
67 it acts as a consumer only.
68 As a producer of information it periodically
69 queries the state of the system and constructs
70 status messages which are broadcasted or multicasted on a network.
71 As a consumer of information, it listens for other
73 servers' status messages, validating them, then recording
74 them in a collection of files located in the directory
79 option enables insecure mode, which causes
81 to ignore the source port on incoming packets.
89 interfaces. This is useful if you do not wish to keep dial on demand
90 interfaces permanently active.
94 option enables listen mode, which causes
96 to not broadcast any information.
97 This allows you to monitor other machines'
99 information, without broadcasting your own.
105 to use IP multicast (instead of
106 broadcast) on all interfaces that have
107 the IFF_MULTICAST flag set in their "ifnet" structs
108 (excluding the loopback interface). The multicast
109 reports are sent with a time-to-live of 1, to prevent
110 forwarding beyond the directly-connected subnet(s).
114 argument is supplied with the
118 will send IP multicast datagrams with a
121 via a SINGLE interface rather
124 must be between 0 and
125 32 (or MAX_MULTICAST_SCOPE). Note that
131 specifies transmission on one interface only.
137 argument, the program accepts multicast
139 reports from all multicast-capable interfaces. If a
141 argument is given, it accepts multicast reports from only one interface, the
142 one on which reports are sent (which may be controlled via the host's routing
143 table). Regardless of the
145 option, the program accepts broadcast or
146 unicast reports from all interfaces. Thus, this program will hear the
147 reports of old, non-multicasting
149 but, if multicasting is used,
152 won't hear the reports generated by this program.
154 The server transmits and receives messages at the port indicated
155 in the ``who'' service specification; see
157 The messages sent and received, are of the form:
158 .Bd -literal -offset indent
160 char out_line[8]; /* tty name */
161 char out_name[8]; /* user id */
162 long out_time; /* time on */
171 char wd_hostname[32];
175 struct outmp we_utmp;
177 } wd_we[1024 / sizeof (struct whoent)];
181 All fields are converted to network byte order prior to
182 transmission. The load averages are as calculated by the
184 program, and represent load averages over the 5, 10, and 15 minute
185 intervals prior to a server's transmission; they are multiplied by 100
186 for representation in an integer. The host name
187 included is that returned by the
189 system call, with any trailing domain name omitted.
190 The array at the end of the message contains information about
191 the users logged in to the sending machine. This information
192 includes the contents of the
194 entry for each non-idle terminal line and a value indicating the
195 time in seconds since a character was last received on the terminal line.
197 Messages received by the
199 server are discarded unless they originated at an
203 option was specified. In addition, if the host's name, as specified
204 in the message, contains any unprintable
207 message is discarded. Valid messages received by
209 are placed in files named
213 These files contain only the most recent message, in the
214 format described above.
216 Status messages are generated approximately once every
223 every 30 minutes to guard against
224 the possibility that this file is not the system
225 image currently operating.
230 Status information should be sent only upon request rather than continuously.
231 People often interpret the server dying
232 or network communication failures
233 as a machine going down.