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ipnodes(4)                       File Formats                       ipnodes(4)

       ipnodes - local database associating names of nodes with IP addresses


       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
       System (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 <&lt;SPACE>&gt; and/or  <&lt;TAB>&gt;  characters.
       The  first item on a line is the node's IP address. The second entry is
       the node's official name. Subsequent  entries  on  the  same  line  are
       alternative  names  for the same machine, or "nicknames." Nicknames are

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

       A call to getipnodebyname(3SOCKET) returns a hostent structure contain-
       ing  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 interpreted using the
            inet_addr routine from the Internet address manipulation  library,

         o  The  IP  Version 6 protocol [IPV6], defined in RFC 1884 and inter-
            preted using the inet_pton() routine  from  the  Internet  address
            manipulation library. See inet(3SOCKET).

       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  components 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 max-
       imum 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 restriction  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:

       2001:0db8:3c4d:55:a00:20ff:fe8e:f3ad        myhost           # John Smith

        getipnodebyname(3SOCKET),       inet(3SOCKET),       nsswitch.conf(4),
       resolv.conf(4), hosts(4)

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

       Harrenstien, K., Stahl, M., and Feinler, E., RFC 952, DOD INTERNET HOST
       TABLE SPECIFICATION, Network Working Group, October 1985.

       Hinden, R., and Deering, S., editors, RFC 1884, IP Version 6 Addressing
       Architecture, Network Working Group, December, 1995.

       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.

SunOS 5.10                        15 Dec 2004                       ipnodes(4)