181 lines
5.0 KiB
Groff
181 lines
5.0 KiB
Groff
.\" $NetBSD: networks.5,v 1.12 2000/11/17 10:14:18 lukem Exp $
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.\"
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.\" Copyright (c) 1983, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)networks.5 8.1 (Berkeley) 6/5/93
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.\"
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.Dd November 17, 2000
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.Dt NETWORKS 5
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.Os
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.Sh NAME
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.Nm networks
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.Nd Internet Protocol network name data base
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.Sh DESCRIPTION
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The
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.Nm
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file is used as a local source to translate between Internet Protocol
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.Pq Tn IP
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network addresses and network names (and vice versa).
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It can be used in conjunction with the DNS,
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.\"and the
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.\".Tn NIS
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.\"maps
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.\".Sq networks.byaddr ,
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.\"and
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.\".Sq networks.byname ,
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as controlled by
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.Xr nsswitch.conf 5 .
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.Pp
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While the
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.Nm
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file was originally intended to be an exhaustive list of all
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.Tn IP
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networks that the local host could communicate with, distribution
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and update of such a list for the world-wide
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.Tn Internet
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(or, indeed, for any large "enterprise" network) has proven to be
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prohibitive, so the Domain Name System
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.Pq Tn DNS
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is used instead, except as noted.
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.Pp
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For each
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.Tn IP
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network a single line should be present with the following information:
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.Dl name network [alias ...]
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.Pp
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These are:
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.Bl -tag -width network -offset indent -compact
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.It Em name
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Official network name
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.It Em network
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IP network number
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.It Em alias
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Network alias
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.El
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.Pp
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Items are separated by any number of blanks and/or tab characters.
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A
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.Dq \&#
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indicates the beginning of a comment; characters up to the end of
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the line are not interpreted by routines which search the file.
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.Pp
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Network number may be specified in the conventional dot
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.Pq Dq \&.
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notation using the
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.Xr inet_network 3
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routine
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from the
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.Tn IP
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address manipulation library,
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.Xr inet 3 .
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Network names may contain
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.Qq a
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through
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.Qq z ,
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zero through nine, and dash.
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.Pp
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.Tn IP
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network numbers on the
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.Tn Internet
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are generally assigned to a site by its Internet Service Provider
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.Pq Tn ISP ,
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who, in turn, get network address space assigned to them by one of
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the regional Internet Registries (e.g. ARIN, RIPE NCC, APNIC).
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These registries, in turn, answer to the Internet Assigned Numbers
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Authority
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.Pq Tn IANA .
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.Pp
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If a site changes its ISP from one to another, it will generally
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be required to change all its assigned IP addresses as part of the
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conversion; that is, return the previous network numbers to the previous
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.Tn ISP ,
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and assign addresses to its hosts from
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.Tn IP
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network address space given by the new
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.Tn ISP .
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Thus, it is best for a savvy network manager to configure his
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hosts for easy renumbering, to preserve his ability to easily
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change his
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.Tn ISP
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should the need arise.
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.Sh FILES
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.Bl -tag -width /etc/networks -compact
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.It Pa /etc/networks
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The
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.Nm
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file resides in
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.Pa /etc .
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.El
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.Sh SEE ALSO
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.Xr getnetent 3 ,
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.Xr resolv.conf 5 ,
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.Xr nsswitch.conf 5 ,
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.Xr hostname 7 ,
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.Xr dhclient 8 ,
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.Xr dhcpd 8 ,
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.Xr named 8 ,
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.Rs
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.%R RFC
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.%N 2317
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.%D March 1998
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.%T "Classless IN-ADDR.ARPA delegation"
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.Re
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.Rs
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.%R RFC
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.%N 1918
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.%D February 1996
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.%T "Address Allocation for Private Internets"
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.Re
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.Rs
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.%R RFC
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.%N 1627
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.%D July 1994
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.%T "Network 10 Considered Harmful"
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.Re
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.Rs
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.%R RFC
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.%N 1519
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.%D September 1993
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.%T "Classless Inter-Domain Routing (CIDR): an Address Assignment and Aggregation Strategy"
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.Re
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.Rs
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.%R RFC
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.%N 1101
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.%D April 1989
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.%T "DNS Encoding of Network Names and Other Types"
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.Re
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.Sh HISTORY
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The
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.Nm
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file format appeared in
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.Bx 4.2 .
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