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.\" @(#)hosts.5 8.2 (Berkeley) 12/11/93 33.\" $FreeBSD: src/share/man/man5/hosts.5,v 1.5.2.3 2001/08/17 13:08:47 ru Exp $ 34.\" $DragonFly: src/share/man/man5/hosts.5,v 1.2 2003/06/17 04:37:00 dillon Exp $ 35.\" 36.Dd December 11, 1993 37.Dt HOSTS 5 38.Os 39.Sh NAME 40.Nm hosts 41.Nd host name data base 42.Sh DESCRIPTION 43The 44.Nm 45file contains information regarding 46the known hosts on the network. 47For each host a single line should be present 48with the following information: 49.Bd -unfilled -offset indent 50Internet address 51official host name 52aliases 53.Ed 54.Pp 55Items are separated by any number of blanks and/or 56tab characters. A ``#'' indicates the beginning of 57a comment; characters up to the end of the line are 58not interpreted by routines which search the file. 59.Pp 60When using the name server 61.Xr named 8 , 62this file provides a backup used when the name server 63is not running. 64For the name server, it is suggested that only a few addresses 65be included in this file. 66These include addresses for the local interfaces that 67.Xr ifconfig 8 68needs at boot time and a few machines on the local network. 69.Pp 70This file may be created from the official host 71data base maintained at the Network Information Control 72Center 73.Pq Tn NIC , 74though local changes may be required 75to bring it up to date regarding unofficial aliases 76and/or unknown hosts. As the data base maintained at 77.Tn NIC 78is incomplete, use of the name server is recommended for 79sites on the 80.Tn DARPA 81Internet. 82.Pp 83Network addresses are specified in the conventional 84``.'' (dot) notation using the 85.Xr inet_addr 3 86routine 87from the Internet address manipulation library, 88.Xr inet 3 . 89Host names may contain any printable 90character other than a field delimiter, newline, 91or comment character. 92.Sh FILES 93.Bl -tag -width /etc/hosts -compact 94.It Pa /etc/hosts 95The 96.Nm 97file resides in 98.Pa /etc . 99.El 100.Sh SEE ALSO 101.Xr gethostbyname 3 , 102.Xr ifconfig 8 , 103.Xr named 8 104.Rs 105.%T "Name Server Operations Guide for BIND" 106.Re 107.Sh HISTORY 108The 109.Nm 110file format appeared in 111.Bx 4.2 . 112