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diff --git a/man/man5/hosts.5 b/man/man5/hosts.5 new file mode 100644 index 0000000..bab4455 --- /dev/null +++ b/man/man5/hosts.5 @@ -0,0 +1,122 @@ +.\" Copyright (c) 2000 Manoj Srivastava <srivasta@debian.org> +.\" +.\" SPDX-License-Identifier: GPL-2.0-or-later +.\" +.\" Minor polishing, aeb +.\" Modified, 2002-06-16, Mike Coleman +.\" +.TH hosts 5 2024-05-02 "Linux man-pages (unreleased)" +.SH NAME +hosts \- static table lookup for hostnames +.SH SYNOPSIS +.nf +.B /etc/hosts +.fi +.SH DESCRIPTION +This manual page describes the format of the +.I /etc/hosts +file. +This file is a simple text file that associates IP addresses +with hostnames, one line per IP address. +For each host a single +line should be present with the following information: +.RS +.P +IP_address canonical_hostname [aliases...] +.RE +.P +The IP address can conform to either IPv4 or IPv6. +Fields of the entry are separated by any number of blanks and/or +tab characters. +Text from a "#" character until the end of the line is +a comment, and is ignored. +Host names may contain only alphanumeric +characters, minus signs ("\-"), and periods ("."). +They must begin with an +alphabetic character and end with an alphanumeric character. +Optional aliases provide for name changes, alternate spellings, +shorter hostnames, or generic hostnames (for example, +.IR localhost ). +If required, a host may have two separate entries in this file; +one for each version of the Internet Protocol (IPv4 and IPv6). +.P +The Berkeley Internet Name Domain (BIND) Server implements the +Internet name server for UNIX systems. +It augments or replaces the +.I /etc/hosts +file or hostname lookup, and frees a host from relying on +.I /etc/hosts +being up to date and complete. +.P +In modern systems, even though the host table has been superseded by +DNS, it is still widely used for: +.TP +.B bootstrapping +Most systems have a small host table containing the name and address +information for important hosts on the local network. +This is useful +when DNS is not running, for example during system bootup. +.TP +.B NIS +Sites that use NIS use the host table as input to the NIS host +database. +Even though NIS can be used with DNS, most NIS sites still +use the host table with an entry for all local hosts as a backup. +.TP +.B isolated nodes +Very small sites that are isolated from the network use the host table +instead of DNS. +If the local information rarely changes, and the +network is not connected to the Internet, DNS offers little +advantage. +.SH FILES +.I /etc/hosts +.SH NOTES +Modifications to this file normally take effect immediately, +except in cases where the file is cached by applications. +.SS Historical notes +RFC\ 952 gave the original format for the host table, though it has +since changed. +.P +Before the advent of DNS, the host table was the only way of resolving +hostnames on the fledgling Internet. +Indeed, this file could be +created from the official host data base maintained at the Network +Information Control Center (NIC), though local changes were often +required to bring it up to date regarding unofficial aliases and/or +unknown hosts. +The NIC no longer maintains the hosts.txt files, +though looking around at the time of writing (circa 2000), there are +historical hosts.txt files on the WWW. +I just found three, from 92, +94, and 95. +.SH EXAMPLES +.EX +# The following lines are desirable for IPv4 capable hosts +127.0.0.1 localhost +\& +# 127.0.1.1 is often used for the FQDN of the machine +127.0.1.1 thishost.example.org thishost +192.168.1.10 foo.example.org foo +192.168.1.13 bar.example.org bar +146.82.138.7 master.debian.org master +209.237.226.90 www.opensource.org +\& +# The following lines are desirable for IPv6 capable hosts +::1 localhost ip6\-localhost ip6\-loopback +ff02::1 ip6\-allnodes +ff02::2 ip6\-allrouters +.EE +.SH SEE ALSO +.BR hostname (1), +.BR resolver (3), +.BR host.conf (5), +.BR resolv.conf (5), +.BR resolver (5), +.BR hostname (7), +.BR named (8) +.P +Internet RFC\ 952 +.\" .SH AUTHOR +.\" This manual page was written by Manoj Srivastava <srivasta@debian.org>, +.\" for the Debian GNU/Linux system. |