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.\" @(#)hosts.5 8.2 (Berkeley) 12/11/93 29.\" $FreeBSD: src/share/man/man5/hosts.5,v 1.10 2004/07/03 18:29:22 ru Exp $ 30.\" $DragonFly: src/share/man/man5/hosts.5,v 1.2 2003/06/17 04:37:00 dillon Exp $ 31.\" 32.Dd December 11, 1993 33.Dt HOSTS 5 34.Os 35.Sh NAME 36.Nm hosts 37.Nd host name data base 38.Sh DESCRIPTION 39The 40.Nm 41file contains information regarding 42the known hosts on the network. 43It can be used in conjunction with DNS, and the NIS 44maps `hosts.byaddr' and `hosts.byname', as controlled by 45.Xr nsswitch.conf 5 . 46For each host a single line should be present 47with the following information: 48.Bd -unfilled -offset indent 49Internet address 50official host name 51aliases 52.Ed 53.Pp 54Items are separated by any number of blanks and/or 55tab characters. 56A ``#'' 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. 77As the data base maintained at 78.Tn NIC 79is incomplete, use of the name server is recommended for 80sites on the 81.Tn DARPA 82Internet. 83.Pp 84Network addresses are specified in the conventional 85``.'' (dot) notation using the 86.Xr inet_addr 3 87routine 88from the Internet address manipulation library, 89.Xr inet 3 . 90Host names may contain any printable 91character other than a field delimiter, newline, 92or comment character. 93.Sh FILES 94.Bl -tag -width /etc/hosts -compact 95.It Pa /etc/hosts 96The 97.Nm 98file resides in 99.Pa /etc . 100.El 101.Sh SEE ALSO 102.Xr gethostbyname 3 , 103.Xr nsswitch.conf 5 , 104.Xr ifconfig 8 , 105.Xr named 8 106.Rs 107.%T "Name Server Operations Guide for BIND" 108.Re 109.Sh HISTORY 110The 111.Nm 112file format appeared in 113.Bx 4.2 . 114