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NAME    [Toc]    [Back]

     networks - Internet Protocol network name database

DESCRIPTION    [Toc]    [Back]

     The networks file is used as a local source to translate between Internet
     Protocol  (IP) network addresses and network names (and vice
versa).  It
     can be used in  conjunction  with  the  Domain  Name  System

     While the networks file was originally intended to be an exhaustive list
     of all IP networks that the  local  host  could  communicate
with, distribution
  and  update of such a list for the world-wide Internet
(or, indeed,
     for any large "enterprise" network) has proven  to  be  prohibitive, so the
     Domain Name System is used instead, except as noted.

     For  each  IP  network, a single line should be present with
the following

           official network name
           ip network number

     Items are separated by any number of blanks and/or tab characters.

     A hash mark (`#') indicates the beginning of a comment; subsequent characters
 up to the end of the line are not interpreted by routines which
     search the file.

     Network  number  may  be  specified  in the conventional `.'
(dot) notation
     using the inet_network(3) routine from the IP address manipulation library,
  inet(3).  Network names may contain "a" through "z",
zero through
     nine, and dash (`-').

     IP network numbers on the Internet are generally assigned to
a site by
     its  Internet Service Provider (ISP), who, in turn, get network address
     space assigned to them by one of the regional Internet  Registries (e.g.,
     ARIN,  RIPE  NCC, APNIC).  These registries, in turn, answer
to the Internet
 Assigned Numbers Authority (IANA).

     If a site changes its ISP from one to another, it will  generally be required
  to  change  all its assigned IP addresses as part of
the conversion;
     that is, return the previous network numbers to the previous
ISP and assign
  addresses  to  its hosts from IP network address space
given by the
     new ISP.  Thus, it is best for a savvy  network  manager  to
configure his
     hosts for easy renumbering, to preserve his ability to easily change his
     ISP should the need arise.

FILES    [Toc]    [Back]


SEE ALSO    [Toc]    [Back]

     getnetent(3),  resolver(3),   resolv.conf(5),   hostname(7),

     Classless IN-ADDR.ARPA delegation, RFC 2317, March 1998.

     Address Allocation for Private Internets, RFC 1918, February

     Network 10 Considered Harmful, RFC 1627, July 1994.

     Classless Inter-Domain Routing (CIDR): an Address Assignment
     Aggregation Strategy, RFC 1519, September 1993.

     DNS  Encoding  of  Network  Names and Other Types, RFC 1101,
April 1989.

HISTORY    [Toc]    [Back]

     The networks file format appeared in 4.2BSD.

OpenBSD      3.6                           June      5,      1993
[ Back ]
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