💾 Archived View for gmi.noulin.net › man › man5 › hosts.5.gmi captured on 2024-08-31 at 14:23:01. Gemini links have been rewritten to link to archived content

View Raw

More Information

⬅️ Previous capture (2022-06-12)

-=-=-=-=-=-=-

HOSTS(5)                                                                Linux Programmer's Manual                                                               HOSTS(5)

NAME
       hosts - static table lookup for hostnames

SYNOPSIS
       /etc/hosts

DESCRIPTION
       This  manual  page describes the format of the /etc/hosts file.  This file is a simple text file that associates IP addresses with hostnames, one line per IP ad‐
       dress.  For each host a single line should be present with the following information:

              IP_address canonical_hostname [aliases...]

       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, localhost).  If required, a host may have two separate entries in this file; one for each version of the Internet Protocol (IPv4
       and IPv6).

       The Berkeley Internet Name Domain (BIND) Server implements the Internet name server for UNIX systems.  It augments or replaces the /etc/hosts  file  or  hostname
       lookup, and frees a host from relying on /etc/hosts being up to date and complete.

       In modern systems, even though the host table has been superseded by DNS, it is still widely used for:

       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.

       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.

       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.

FILES
       /etc/hosts

NOTES
       Modifications to this file normally take effect immediately, except in cases where the file is cached by applications.

   Historical notes
       RFC 952 gave the original format for the host table, though it has since changed.

       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.

EXAMPLES
       # 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.mydomain.org  thishost
       192.168.1.10    foo.mydomain.org       foo
       192.168.1.13    bar.mydomain.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

SEE ALSO
       hostname(1), resolver(3), host.conf(5), resolv.conf(5), resolver(5), hostname(7), named(8)

       Internet RFC 952

Linux                                                                          2021-03-22                                                                       HOSTS(5)