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28 .\" @(#)rwhod.8 8.2 (Berkeley) 12/11/93
35 .Nd system status server
45 utility is the server which maintains the database used by the
50 Its operation is predicated on the ability to
54 messages on a network.
58 utility operates as both a producer and consumer of status information,
61 (listen mode) option is specified, in which case
62 it acts as a consumer only.
63 As a producer of information it periodically
64 queries the state of the system and constructs
65 status messages which are broadcasted or multicasted on a network.
66 As a consumer of information, it listens for other
68 servers' status messages, validating them, then recording
69 them in a collection of files located in the directory
72 The following options are available:
73 .Bl -tag -width indent
75 Enable insecure mode, which causes
77 to ignore the source port on incoming packets.
82 This is useful if you do not wish to keep dial on demand
83 interfaces permanently active.
85 Enable listen mode, which causes
87 to not broadcast any information.
88 This allows you to monitor other machines'
90 information, without broadcasting your own.
94 to use IP multicast (instead of
95 broadcast) on all interfaces that have
96 the IFF_MULTICAST flag set in their "ifnet" structs
97 (excluding the loopback interface).
99 reports are sent with a time-to-live of 1, to prevent
100 forwarding beyond the directly-connected subnet(s).
104 argument is supplied with the
108 will send IP multicast datagrams with a
111 via a SINGLE interface rather
114 must be between 0 and
115 32 (or MAX_MULTICAST_SCOPE).
122 specifies transmission on one interface only.
128 argument, the program accepts multicast
130 reports from all multicast-capable interfaces.
133 argument is given, it accepts multicast reports from only one interface, the
134 one on which reports are sent (which may be controlled via the host's routing
138 option, the program accepts broadcast or
139 unicast reports from all interfaces.
140 Thus, this program will hear the
141 reports of old, non-multicasting
143 but, if multicasting is used,
146 will not hear the reports generated by this program.
149 The server transmits and receives messages at the port indicated
150 in the ``who'' service specification; see
152 The messages sent and received, are of the form:
153 .Bd -literal -offset indent
155 char out_line[8]; /* tty name */
156 char out_name[8]; /* user id */
157 long out_time; /* time on */
166 char wd_hostname[32];
170 struct outmp we_utmp;
172 } wd_we[1024 / sizeof (struct whoent)];
176 All fields are converted to network byte order prior to
178 The load averages are as calculated by the
180 program, and represent load averages over the 5, 10, and 15 minute
181 intervals prior to a server's transmission; they are multiplied by 100
182 for representation in an integer.
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.
190 includes the contents of the entry from the user accounting database
191 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.
201 In addition, if the host's name, as specified
202 in the message, contains any unprintable
205 message is discarded.
206 Valid messages received by
208 are placed in files named
212 These files contain only the most recent message, in the
213 format described above.
215 Status messages are generated approximately once every
226 Status information should be sent only upon request rather than continuously.
227 People often interpret the server dying
228 or network communication failures
229 as a machine going down.