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.\" 34.Dd December 11, 1993 35.Dt RWHOD 8 36.Os BSD 4.2 37.Sh NAME 38.Nm rwhod 39.Nd system status server 40.Sh SYNOPSIS 41.Nm rwhod 42.Op Fl m Op Ar ttl 43.Sh DESCRIPTION 44.Nm Rwhod 45is the server which maintains the database used by the 46.Xr rwho 1 47and 48.Xr ruptime 1 49programs. Its operation is predicated on the ability to 50.Em broadcast 51or 52.Em multicast 53messages on a network. 54.Pp 55.Nm Rwhod 56operates as both a producer and consumer of status information. 57As a producer of information it periodically 58queries the state of the system and constructs 59status messages which are broadcasted or multicasted on a network. 60As a consumer of information, it listens for other 61.Nm rwhod 62servers' status messages, validating them, then recording 63them in a collection of files located in the directory 64.Pa /var/rwho . 65.Pp 66The 67.Fl m 68option causes rwhod to use IP multicast (instead of 69broadcast) on all interfaces that have 70the IFF_MULTICAST flag set in their "ifnet" structs 71(excluding the loopback interface). The multicast 72reports are sent with a time-to-live of 1, to prevent 73forwarding beyond the directly-connected subnet(s). 74.Pp 75If the optional 76.Ar ttl 77argument is supplied with the 78.Fl m 79flag, rwhod will send IP multicast datagrams with a 80time-to-live of <ttl>, via a SINGLE interface rather 81than all interfaces. <ttl> must be between 0 and 8232 (or MAX_MULTICAST_SCOPE). Note that 83.Fl m Ar 1 84is different than 85.Fl m , 86in that 87.Fl m Ar 1 88specifies transmission on one interface only. 89.Pp 90When 91.Fl m 92is used without a 93.Ar ttl 94argument, the program accepts multicast 95rwhod reports from all multicast-capable interfaces. If a 96.Ar ttl 97argument is given, it accepts multicast reports from only one interface, the 98one on which reports are sent (which may be controlled via the host's routing 99table). Regardless of the "-m" option, the program accepts broadcast or 100unicast reports from all interfaces. Thus, this program will hear the 101reports of old, non-multicasting rwhods, but, if multicasting is used, 102those old rwhods won't hear the reports generated by this program. 103.Pp 104The server transmits and receives messages at the port indicated 105in the ``rwho'' service specification; see 106.Xr services 5 . 107The messages sent and received, are of the form: 108.Bd -literal -offset indent 109struct outmp { 110 char out_line[8]; /* tty name */ 111 char out_name[8]; /* user id */ 112 long out_time; /* time on */ 113}; 114 115struct whod { 116 char wd_vers; 117 char wd_type; 118 char wd_fill[2]; 119 int wd_sendtime; 120 int wd_recvtime; 121 char wd_hostname[32]; 122 int wd_loadav[3]; 123 int wd_boottime; 124 struct whoent { 125 struct outmp we_utmp; 126 int we_idle; 127 } wd_we[1024 / sizeof (struct whoent)]; 128}; 129.Ed 130.Pp 131All fields are converted to network byte order prior to 132transmission. The load averages are as calculated by the 133.Xr w 1 134program, and represent load averages over the 5, 10, and 15 minute 135intervals prior to a server's transmission; they are multiplied by 100 136for representation in an integer. The host name 137included is that returned by the 138.Xr gethostname 3 139system call, with any trailing domain name omitted. 140The array at the end of the message contains information about 141the users logged in to the sending machine. This information 142includes the contents of the 143.Xr utmp 5 144entry for each non-idle terminal line and a value indicating the 145time in seconds since a character was last received on the terminal line. 146.Pp 147Messages received by the 148.Nm rwho 149server are discarded unless they originated at an 150.Nm rwho 151server's port. In addition, if the host's name, as specified 152in the message, contains any unprintable 153.Tn ASCII 154characters, the 155message is discarded. Valid messages received by 156.Nm rwhod 157are placed in files named 158.Pa whod.hostname 159in the directory 160.Pa /var/rwho . 161These files contain only the most recent message, in the 162format described above. 163.Pp 164Status messages are generated approximately once every 1653 minutes. 166.Nm Rwhod 167performs an 168.Xr nlist 3 169on 170.Pa /kernel 171every 30 minutes to guard against 172the possibility that this file is not the system 173image currently operating. 174.Sh SEE ALSO 175.Xr ruptime 1 , 176.Xr rwho 1 177.Sh BUGS 178Status information should be sent only upon request rather than continuously. 179People often interpret the server dying 180or network communication failures 181as a machine going down. 182.Sh HISTORY 183The 184.Nm 185command appeared in 186.Bx 4.2 . 187