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.\" $FreeBSD$ 30.\" 31.Dd August 8, 2017 32.Dt RWHOD 8 33.Os 34.Sh NAME 35.Nm rwhod 36.Nd system status server 37.Sh SYNOPSIS 38.Nm 39.Op Fl i 40.Op Fl p 41.Op Fl l 42.Op Fl m Op Ar ttl 43.Sh DESCRIPTION 44The 45.Nm 46utility is the server which maintains the database used by the 47.Xr rwho 1 48and 49.Xr ruptime 1 50programs. 51Its operation is predicated on the ability to 52.Em broadcast 53or 54.Em multicast 55messages on a network. 56.Pp 57The 58.Nm 59utility operates as both a producer and consumer of status information, 60unless the 61.Fl l 62(listen mode) option is specified, in which case 63it acts as a consumer only. 64As a producer of information it periodically 65queries the state of the system and constructs 66status messages which are broadcasted or multicasted on a network. 67As a consumer of information, it listens for other 68.Nm 69servers' status messages, validating them, then recording 70them in a collection of files located in the directory 71.Pa /var/rwho . 72.Pp 73The following options are available: 74.Bl -tag -width indent 75.It Fl i 76Enable insecure mode, which causes 77.Nm 78to ignore the source port on incoming packets. 79.It Fl p 80Ignore all 81.Dv POINTOPOINT 82interfaces. 83This is useful if you do not wish to keep dial on demand 84interfaces permanently active. 85.It Fl l 86Enable listen mode, which causes 87.Nm 88to not broadcast any information. 89This allows you to monitor other machines' 90.Nm 91information, without broadcasting your own. 92.It Fl m Op Ar ttl 93Cause 94.Nm 95to use IP multicast (instead of 96broadcast) on all interfaces that have 97the IFF_MULTICAST flag set in their "ifnet" structs 98(excluding the loopback interface). 99The multicast 100reports are sent with a time-to-live of 1, to prevent 101forwarding beyond the directly-connected subnet(s). 102.Pp 103If the optional 104.Ar ttl 105argument is supplied with the 106.Fl m 107flag, 108.Nm 109will send IP multicast datagrams with a 110time-to-live of 111.Ar ttl , 112via a SINGLE interface rather 113than all interfaces. 114.Ar ttl 115must be between 0 and 11632 (or MAX_MULTICAST_SCOPE). 117Note that 118.Fl m Ar 1 119is different from 120.Fl m , 121in that 122.Fl m Ar 1 123specifies transmission on one interface only. 124.Pp 125When 126.Fl m 127is used without a 128.Ar ttl 129argument, the program accepts multicast 130.Nm 131reports from all multicast-capable interfaces. 132If a 133.Ar ttl 134argument is given, it accepts multicast reports from only one interface, the 135one on which reports are sent (which may be controlled via the host's routing 136table). 137Regardless of the 138.Fl m 139option, the program accepts broadcast or 140unicast reports from all interfaces. 141Thus, this program will hear the 142reports of old, non-multicasting 143.Nm Ns s , 144but, if multicasting is used, 145those old 146.Nm Ns s 147will not hear the reports generated by this program. 148.El 149.Pp 150The server transmits and receives messages at the port indicated 151in the ``who'' service specification; see 152.Xr services 5 . 153The messages sent and received, are of the form: 154.Bd -literal -offset indent 155struct outmp { 156 char out_line[8]; /* tty name */ 157 char out_name[8]; /* user id */ 158 long out_time; /* time on */ 159}; 160 161struct whod { 162 char wd_vers; 163 char wd_type; 164 char wd_fill[2]; 165 int wd_sendtime; 166 int wd_recvtime; 167 char wd_hostname[32]; 168 int wd_loadav[3]; 169 int wd_boottime; 170 struct whoent { 171 struct outmp we_utmp; 172 int we_idle; 173 } wd_we[1024 / sizeof (struct whoent)]; 174}; 175.Ed 176.Pp 177All fields are converted to network byte order prior to 178transmission. 179The load averages are as calculated by the 180.Xr w 1 181program, and represent load averages over the 5, 10, and 15 minute 182intervals prior to a server's transmission; they are multiplied by 100 183for representation in an integer. 184The host name 185included is that returned by the 186.Xr gethostname 3 187system call, with any trailing domain name omitted. 188The array at the end of the message contains information about 189the users logged in to the sending machine. 190This information 191includes the contents of the entry from the user accounting database 192for each non-idle terminal line and a value indicating the 193time in seconds since a character was last received on the terminal line. 194.Pp 195Messages received by the 196.Nm rwho 197server are discarded unless they originated at an 198.Nm rwho 199server's port or the 200.Fl i 201option was specified. 202In addition, if the host's name, as specified 203in the message, contains any unprintable 204.Tn ASCII 205characters, the 206message is discarded. 207Valid messages received by 208.Nm 209are placed in files named 210.Pa whod.hostname 211in the directory 212.Pa /var/rwho . 213These files contain only the most recent message, in the 214format described above. 215.Pp 216Status messages are generated approximately once every 2173 minutes. 218The 219.Nm 220utility performs an 221.Xr nlist 3 222on 223.Pa /boot/kernel/kernel 224every 30 minutes to guard against 225the possibility that this file is not the system 226image currently operating. 227.Sh SEE ALSO 228.Xr ruptime 1 , 229.Xr rwho 1 230.Sh HISTORY 231The 232.Nm 233utility appeared in 234.Bx 4.2 . 235.Sh BUGS 236Status information should be sent only upon request rather than continuously. 237People often interpret the server dying 238or network communication failures 239as a machine going down. 240