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.\" $FreeBSD$ 30.\" 31.Dd May 25, 2021 32.Dt HOSTS 5 33.Os 34.Sh NAME 35.Nm hosts 36.Nd host name data base 37.Sh DESCRIPTION 38The 39.Nm 40file contains information regarding 41the known hosts on the network. 42It can be used in conjunction with DNS, and the NIS 43maps `hosts.byaddr' and `hosts.byname', as controlled by 44.Xr nsswitch.conf 5 . 45For each host a single line should be present 46with the following information: 47.Bd -unfilled -offset indent 48Internet address 49official host name 50aliases 51.Ed 52.Pp 53Items are separated by any number of blanks and/or 54tab characters. 55A ``#'' indicates the beginning of 56a comment; characters up to the end of the line are 57not interpreted by routines which search the file. 58.Pp 59This file provides a backup used when the name server 60is not running. 61For the name server, it is suggested that only a few addresses 62be included in this file. 63These include addresses for the local interfaces that 64.Xr ifconfig 8 65needs at boot time and a few machines on the local network. 66.Pp 67Network addresses are specified in either the conventional 68``.'' (dot) notation for IPv4 or colon hexadecimal notation for IPv6, 69as understood by the 70.Xr inet_pton 3 71routine 72from the Internet address manipulation library, 73.Xr inet 3 . 74Host names may contain any printable 75character other than a field delimiter, newline, 76or comment character. 77.Sh FILES 78.Bl -tag -width /etc/hosts -compact 79.It Pa /etc/hosts 80The 81.Nm 82file resides in 83.Pa /etc . 84.El 85.Sh SEE ALSO 86.Xr gethostbyname 3 , 87.Xr inet 3 , 88.Xr nsswitch.conf 5 , 89.Xr ifconfig 8 90.Rs 91.%T "Name Server Operations Guide for BIND" 92.Re 93.Sh HISTORY 94The 95.Nm 96file format appeared in 97.Bx 4.1c . 98