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. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)rwhod.8 8.2 (Berkeley) 12/11/93 29.\" $FreeBSD: src/usr.sbin/rwhod/rwhod.8,v 1.13.2.4 2003/03/11 22:31:33 trhodes Exp $ 30.\" $DragonFly: src/usr.sbin/rwhod/rwhod.8,v 1.7 2008/09/02 11:50:47 matthias Exp $ 31.\" 32.Dd September 2, 2008 33.Dt RWHOD 8 34.Os 35.Sh NAME 36.Nm rwhod 37.Nd system status server 38.Sh SYNOPSIS 39.Nm 40.Op Fl i 41.Op Fl p 42.Op Fl l 43.Op Fl g Ar time 44.Op Fl m Op Ar ttl 45.Sh DESCRIPTION 46The 47.Nm 48utility is the server which maintains the database used by the 49.Xr rwho 1 50and 51.Xr ruptime 1 52programs. Its operation is predicated on the ability to 53.Em broadcast 54or 55.Em multicast 56messages on a network. 57.Pp 58The 59.Nm 60utility operates as both a producer and consumer of status information, 61unless the 62.Fl l 63(listen mode) option is specified, in which case 64it acts as a consumer only. 65As a producer of information it periodically 66queries the state of the system and constructs 67status messages which are broadcasted or multicasted on a network. 68As a consumer of information, it listens for other 69.Nm 70servers' status messages, validating them, then recording 71them in a collection of files located in the directory 72.Pa /var/rwho . 73.Pp 74The 75.Fl i 76option enables insecure mode, which causes 77.Nm 78to ignore the source port on incoming packets. 79.Pp 80The 81.Fl g 82option allows for the broadcast 83.Ar time 84for 85.Nm 86to be reduced below 3 minutes. This enables for more 'real' time statistics 87of the host. 88The 89.Ar time 90operand can be given as 30 (30 seconds) or 1m (1 minute), for example. 91.Pp 92The 93.Fl p 94option tells 95.Nm 96to ignore all 97.Dv POINTOPOINT 98interfaces. This is useful if you do not wish to keep dial on demand 99interfaces permanently active. 100.Pp 101The 102.Fl l 103option enables listen mode, which causes 104.Nm 105to not broadcast any information. 106This allows you to monitor other machines' 107.Nm 108information, without broadcasting your own. 109.Pp 110The 111.Fl m 112option causes 113.Nm 114to use IP multicast (instead of 115broadcast) on all interfaces that have 116the IFF_MULTICAST flag set in their "ifnet" structs 117(excluding the loopback interface). The multicast 118reports are sent with a time-to-live of 1, to prevent 119forwarding beyond the directly-connected subnet(s). 120.Pp 121If the optional 122.Ar ttl 123argument is supplied with the 124.Fl m 125flag, 126.Nm 127will send IP multicast datagrams with a 128time-to-live of 129.Ar ttl , 130via a SINGLE interface rather 131than all interfaces. 132.Ar ttl 133must be between 0 and 13432 (or MAX_MULTICAST_SCOPE). Note that 135.Fl m Ar 1 136is different from 137.Fl m , 138in that 139.Fl m Ar 1 140specifies transmission on one interface only. 141.Pp 142When 143.Fl m 144is used without a 145.Ar ttl 146argument, the program accepts multicast 147.Nm 148reports from all multicast-capable interfaces. If a 149.Ar ttl 150argument is given, it accepts multicast reports from only one interface, the 151one on which reports are sent (which may be controlled via the host's routing 152table). Regardless of the 153.Fl m 154option, the program accepts broadcast or 155unicast reports from all interfaces. Thus, this program will hear the 156reports of old, non-multicasting 157.Nm Ns s , 158but, if multicasting is used, 159those old 160.Nm Ns s 161won't hear the reports generated by this program. 162.Pp 163The server transmits and receives messages at the port indicated 164in the ``who'' service specification; see 165.Xr services 5 . 166The messages sent and received, are of the form: 167.Bd -literal -offset indent 168struct outmp { 169 char out_line[8]; /* tty name */ 170 char out_name[8]; /* user id */ 171 long out_time; /* time on */ 172}; 173 174struct whod { 175 char wd_vers; 176 char wd_type; 177 char wd_fill[2]; 178 int wd_sendtime; 179 int wd_recvtime; 180 char wd_hostname[32]; 181 int wd_loadav[3]; 182 int wd_boottime; 183 struct whoent { 184 struct outmp we_utmp; 185 int we_idle; 186 } wd_we[1024 / sizeof (struct whoent)]; 187}; 188.Ed 189.Pp 190All fields are converted to network byte order prior to 191transmission. The load averages are as calculated by the 192.Xr w 1 193program, and represent load averages over the 5, 10, and 15 minute 194intervals prior to a server's transmission; they are multiplied by 100 195for representation in an integer. The host name 196included is that returned by the 197.Xr gethostname 3 198system call, with any trailing domain name omitted. 199The array at the end of the message contains information about 200the users logged in to the sending machine. This information 201includes the contents of the 202.Xr utmp 5 203entry for each non-idle terminal line and a value indicating the 204time in seconds since a character was last received on the terminal line. 205.Pp 206Messages received by the 207.Nm rwho 208server are discarded unless they originated at an 209.Nm rwho 210server's port or the 211.Fl i 212option was specified. In addition, if the host's name, as specified 213in the message, contains any unprintable 214.Tn ASCII 215characters, the 216message is discarded. Valid messages received by 217.Nm 218are placed in files named 219.Pa whod.hostname 220in the directory 221.Pa /var/rwho . 222These files contain only the most recent message, in the 223format described above. 224.Pp 225Status messages are generated by default approximately once every 2263 minutes. 227.Nm Rwhod 228performs an 229.Xr nlist 3 230on 231.Pa /boot/kernel 232every 30 minutes to guard against 233the possibility that this file is not the system 234image currently operating. 235.Sh SEE ALSO 236.Xr ruptime 1 , 237.Xr rwho 1 238.Sh HISTORY 239The 240.Nm 241utility appeared in 242.Bx 4.2 . 243.Sh BUGS 244Status information should be sent only upon request rather than continuously. 245People often interpret the server dying 246or network communication failures 247as a machine going down. 248