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 1.10 2004/07/03 18:29:22 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. 47It can be used in conjunction with DNS, and the NIS 48maps `hosts.byaddr' and `hosts.byname', as controlled by 49.Xr nsswitch.conf 5 . 50For each host a single line should be present 51with the following information: 52.Bd -unfilled -offset indent 53Internet address 54official host name 55aliases 56.Ed 57.Pp 58Items are separated by any number of blanks and/or 59tab characters. 60A ``#'' indicates the beginning of 61a comment; characters up to the end of the line are 62not interpreted by routines which search the file. 63.Pp 64When using the name server 65.Xr named 8 , 66this file provides a backup used when the name server 67is not running. 68For the name server, it is suggested that only a few addresses 69be included in this file. 70These include addresses for the local interfaces that 71.Xr ifconfig 8 72needs at boot time and a few machines on the local network. 73.Pp 74This file may be created from the official host 75data base maintained at the Network Information Control 76Center 77.Pq Tn NIC , 78though local changes may be required 79to bring it up to date regarding unofficial aliases 80and/or unknown hosts. 81As the data base maintained at 82.Tn NIC 83is incomplete, use of the name server is recommended for 84sites on the 85.Tn DARPA 86Internet. 87.Pp 88Network addresses are specified in the conventional 89``.'' (dot) notation using the 90.Xr inet_addr 3 91routine 92from the Internet address manipulation library, 93.Xr inet 3 . 94Host names may contain any printable 95character other than a field delimiter, newline, 96or comment character. 97.Sh FILES 98.Bl -tag -width /etc/hosts -compact 99.It Pa /etc/hosts 100The 101.Nm 102file resides in 103.Pa /etc . 104.El 105.Sh SEE ALSO 106.Xr gethostbyname 3 , 107.Xr nsswitch.conf 5 , 108.Xr ifconfig 8 , 109.Xr named 8 110.Rs 111.%T "Name Server Operations Guide for BIND" 112.Re 113.Sh HISTORY 114The 115.Nm 116file format appeared in 117.Bx 4.2 . 118