1.\" Copyright (c) 1983, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)rwhod.8 8.2 (Berkeley) 12/11/93 33.\" $FreeBSD: src/usr.sbin/rwhod/rwhod.8,v 1.13.2.4 2003/03/11 22:31:33 trhodes Exp $ 34.\" $DragonFly: src/usr.sbin/rwhod/rwhod.8,v 1.7 2008/09/02 11:50:47 matthias Exp $ 35.\" 36.Dd September 2, 2008 37.Dt RWHOD 8 38.Os 39.Sh NAME 40.Nm rwhod 41.Nd system status server 42.Sh SYNOPSIS 43.Nm 44.Op Fl i 45.Op Fl p 46.Op Fl l 47.Op Fl g Ar time 48.Op Fl m Op Ar ttl 49.Sh DESCRIPTION 50The 51.Nm 52utility is the server which maintains the database used by the 53.Xr rwho 1 54and 55.Xr ruptime 1 56programs. Its operation is predicated on the ability to 57.Em broadcast 58or 59.Em multicast 60messages on a network. 61.Pp 62The 63.Nm 64utility operates as both a producer and consumer of status information, 65unless the 66.Fl l 67(listen mode) option is specified, in which case 68it acts as a consumer only. 69As a producer of information it periodically 70queries the state of the system and constructs 71status messages which are broadcasted or multicasted on a network. 72As a consumer of information, it listens for other 73.Nm 74servers' status messages, validating them, then recording 75them in a collection of files located in the directory 76.Pa /var/rwho . 77.Pp 78The 79.Fl i 80option enables insecure mode, which causes 81.Nm 82to ignore the source port on incoming packets. 83.Pp 84The 85.Fl g 86option allows for the broadcast 87.Ar time 88for 89.Nm 90to be reduced below 3 minutes. This enables for more 'real' time statistics 91of the host. 92The 93.Ar time 94operand can be given as 30 (30 seconds) or 1m (1 minute), for example. 95.Pp 96The 97.Fl p 98option tells 99.Nm 100to ignore all 101.Dv POINTOPOINT 102interfaces. This is useful if you do not wish to keep dial on demand 103interfaces permanently active. 104.Pp 105The 106.Fl l 107option enables listen mode, which causes 108.Nm 109to not broadcast any information. 110This allows you to monitor other machines' 111.Nm 112information, without broadcasting your own. 113.Pp 114The 115.Fl m 116option causes 117.Nm 118to use IP multicast (instead of 119broadcast) on all interfaces that have 120the IFF_MULTICAST flag set in their "ifnet" structs 121(excluding the loopback interface). The multicast 122reports are sent with a time-to-live of 1, to prevent 123forwarding beyond the directly-connected subnet(s). 124.Pp 125If the optional 126.Ar ttl 127argument is supplied with the 128.Fl m 129flag, 130.Nm 131will send IP multicast datagrams with a 132time-to-live of 133.Ar ttl , 134via a SINGLE interface rather 135than all interfaces. 136.Ar ttl 137must be between 0 and 13832 (or MAX_MULTICAST_SCOPE). Note that 139.Fl m Ar 1 140is different from 141.Fl m , 142in that 143.Fl m Ar 1 144specifies transmission on one interface only. 145.Pp 146When 147.Fl m 148is used without a 149.Ar ttl 150argument, the program accepts multicast 151.Nm 152reports from all multicast-capable interfaces. If a 153.Ar ttl 154argument is given, it accepts multicast reports from only one interface, the 155one on which reports are sent (which may be controlled via the host's routing 156table). Regardless of the 157.Fl m 158option, the program accepts broadcast or 159unicast reports from all interfaces. Thus, this program will hear the 160reports of old, non-multicasting 161.Nm Ns s , 162but, if multicasting is used, 163those old 164.Nm Ns s 165won't hear the reports generated by this program. 166.Pp 167The server transmits and receives messages at the port indicated 168in the ``who'' service specification; see 169.Xr services 5 . 170The messages sent and received, are of the form: 171.Bd -literal -offset indent 172struct outmp { 173 char out_line[8]; /* tty name */ 174 char out_name[8]; /* user id */ 175 long out_time; /* time on */ 176}; 177 178struct whod { 179 char wd_vers; 180 char wd_type; 181 char wd_fill[2]; 182 int wd_sendtime; 183 int wd_recvtime; 184 char wd_hostname[32]; 185 int wd_loadav[3]; 186 int wd_boottime; 187 struct whoent { 188 struct outmp we_utmp; 189 int we_idle; 190 } wd_we[1024 / sizeof (struct whoent)]; 191}; 192.Ed 193.Pp 194All fields are converted to network byte order prior to 195transmission. The load averages are as calculated by the 196.Xr w 1 197program, and represent load averages over the 5, 10, and 15 minute 198intervals prior to a server's transmission; they are multiplied by 100 199for representation in an integer. The host name 200included is that returned by the 201.Xr gethostname 3 202system call, with any trailing domain name omitted. 203The array at the end of the message contains information about 204the users logged in to the sending machine. This information 205includes the contents of the 206.Xr utmp 5 207entry for each non-idle terminal line and a value indicating the 208time in seconds since a character was last received on the terminal line. 209.Pp 210Messages received by the 211.Nm rwho 212server are discarded unless they originated at an 213.Nm rwho 214server's port or the 215.Fl i 216option was specified. In addition, if the host's name, as specified 217in the message, contains any unprintable 218.Tn ASCII 219characters, the 220message is discarded. Valid messages received by 221.Nm 222are placed in files named 223.Pa whod.hostname 224in the directory 225.Pa /var/rwho . 226These files contain only the most recent message, in the 227format described above. 228.Pp 229Status messages are generated by default approximately once every 2303 minutes. 231.Nm Rwhod 232performs an 233.Xr nlist 3 234on 235.Pa /boot/kernel 236every 30 minutes to guard against 237the possibility that this file is not the system 238image currently operating. 239.Sh SEE ALSO 240.Xr ruptime 1 , 241.Xr rwho 1 242.Sh HISTORY 243The 244.Nm 245utility appeared in 246.Bx 4.2 . 247.Sh BUGS 248Status information should be sent only upon request rather than continuously. 249People often interpret the server dying 250or network communication failures 251as a machine going down. 252