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.\" $FreeBSD$ 34.\" 35.Dd December 25, 2013 36.Dt HOSTS 5 37.Os 38.Sh NAME 39.Nm hosts 40.Nd host name data base 41.Sh DESCRIPTION 42The 43.Nm 44file contains information regarding 45the known hosts on the network. 46It can be used in conjunction with DNS, and the NIS 47maps `hosts.byaddr' and `hosts.byname', as controlled by 48.Xr nsswitch.conf 5 . 49For each host a single line should be present 50with the following information: 51.Bd -unfilled -offset indent 52Internet address 53official host name 54aliases 55.Ed 56.Pp 57Items are separated by any number of blanks and/or 58tab characters. 59A ``#'' indicates the beginning of 60a comment; characters up to the end of the line are 61not interpreted by routines which search the file. 62.Pp 63This file provides a backup used when the name server 64is not running. 65For the name server, it is suggested that only a few addresses 66be included in this file. 67These include addresses for the local interfaces that 68.Xr ifconfig 8 69needs at boot time and a few machines on the local network. 70.Pp 71This file may be created from the official host 72data base maintained at the Network Information Control 73Center 74.Pq Tn NIC , 75though local changes may be required 76to bring it up to date regarding unofficial aliases 77and/or unknown hosts. 78As the data base maintained at 79.Tn NIC 80is incomplete, use of the name server is recommended for 81sites on the 82.Tn DARPA 83Internet. 84.Pp 85Network addresses are specified in the conventional 86``.'' (dot) notation using the 87.Xr inet_addr 3 88routine 89from the Internet address manipulation library, 90.Xr inet 3 . 91Host names may contain any printable 92character other than a field delimiter, newline, 93or comment character. 94.Sh FILES 95.Bl -tag -width /etc/hosts -compact 96.It Pa /etc/hosts 97The 98.Nm 99file resides in 100.Pa /etc . 101.El 102.Sh SEE ALSO 103.Xr gethostbyname 3 , 104.Xr nsswitch.conf 5 , 105.Xr ifconfig 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