ipnodes - local database associating names of nodes with  IP




     The ipnodes file is a local  database  that  associates  the
     names  of nodes with their Internet Protocol (IP) addresses.
     IP addresses can be either an IPv4 or an IPv6  address.  The
     ipnodes  file  can  be used in conjunction with, or  instead
     of, other ipnodes databases,  including the Domain Name Sys-
     tem  (DNS), the NIS ipnodes map, and the NIS+ ipnodes table.
     Programs use library interfaces to access information in the
     ipnodes file.

     The ipnodes file has one entry for each IP address  of  each
     node.  If  a node has more than one IP address, it will have
     one entry for each, on consecutive  lines.   The  format  of
     each line is:

     IP-address official-node-name nicknames...

     Items are separated by any number of  <SPACE>  and/or  <TAB>
     characters.   The   first  item  on  a line is the node's IP
     address. The second entry is the  node's official name. Sub-
     sequent  entries  on the same line are alternative names for
     the same machine, or "nicknames." Nicknames are optional.

     For a node  with  more  than  one  IP  address,  consecutive
     entries  for these addresses may contain the same or differ-
     ing nicknames.  Different nicknames are useful for assigning
     distinct names to different addresses.

     A call to getipnodebyname(3SOCKET) returns a hostent  struc-
     ture containing
      the  union of all addresses and nicknames  from  each  line
     containing a matching official name or nickname.

     A `#' indicates the beginning of a comment; characters up to
     the  end  of  the  line are not interpreted by routines that
     search the file.

     Network addresses are written in one of two ways:

        o  The conventional "decimal  dot"  notation  and  inter-
           preted  using  the inet_addr routine from the Internet
           address  manipulation library, inet(3SOCKET).

        o  The IP Version 6 protocol [IPV6], defined in RFC  1884
           and interpreted using the inet_pton() routine from the
           Internet    address    manipulation    library.    See

     These interfaces supports node names as defined in  Internet
     RFC 952 which states:

     A "name" (Net, Host, Gateway, or Domain name)   is   a  text
     string  up  to  24 characters drawn from the alphabet (A-Z),
     digits (0-9), minus sign (-), and  period  (.).   Note  that
     periods  are  only  allowed  when they serve to delimit com-
     ponents of "domain style names".  (See RFC 921, "Domain Name
     System  Implementation Schedule," for background).
      No blank or space characters are permitted  as part  of   a
     name.   No distinction is made between upper and lower case.
     The first character must be an  alpha  character.  The  last
     character must not be a minus sign or period.

     Although the interface accepts node  names  longer  than  24
     characters  for  the  node  portion (exclusive of the domain
     component), choosing names for  nodes that adhere to the  24
     character  restriction  will insure maximum interoperability
     on the Internet.

     A node which serves as a GATEWAY should have  "-GATEWAY"  or
     "-GW"  as  part  of  its  name.  Nodes which do not serve as
     Internet gateways should not use "-GATEWAY"  and  "-GW"   as
     part   of   their   names.  A node that is a TAC should have
     "-TAC" as the last part of its node name, if  it  is  a  DoD
     node.  Single character names or nicknames are not allowed.

     RFC 952 has been modified by RFC 1123 to relax the  restric-
     tion on the first character being a digit.


     Example 1: A Typical Line from the ipnodes File

     The following is a typical line from the ipnodes file:

      2::56:a00:20ff:fe7b:b667        foo             # John Smith


     in.named(1M),    getipnodebyname(3SOCKET),    inet(3SOCKET),
     nsswitch.conf(4), resolv.conf(4), hosts(4)

     Braden, B., editor,  RFC  1123,  Requirements  for  Internet
     Hosts  -  Application  and  Support,  Network Working Group,
     October, 1989.

     Harrenstien, K., Stahl, M., and Feinler, E.,  RFC  952,  DOD
     October 1985.
     Hinden, R., and Deering, S., editors, RFC 1884, IP Version 6
     Addressing  Architecture,  Network  Working Group, December,

     Postel, Jon, RFC 921,  Domain  Name  System   Implementation
     Schedule - Revised, Network Working Group, October 1984.


     IPv4 addresses can be defined in the ipnodes file or in  the
     hosts file. See hosts(4).  The ipnodes file will be searched
     for IPv4 addresses when using  the  getipnodebyname(3SOCKET)
     API.  If no matching IPv4 addresses are found in the ipnodes
     file, then the hosts  file  will  be  searched.  To  prevent
     delays  in name resolution and to keep /etc/inet/ipnodes and
     /etc/inet/hosts synchronized, IPv4 addresses defined in  the
     hosts file should be copied to the ipnodes file.

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