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NAME

       netinet/in.h - Internet address family

SYNOPSIS

       #include <netinet/in.h>

DESCRIPTION

       The <netinet/in.h> header shall define the following types:

       in_port_t
              Equivalent to the type uint16_t as defined in <inttypes.h> .

       in_addr_t
              Equivalent to the type uint32_t as defined in <inttypes.h> .

       The sa_family_t type shall be defined as described in <sys/socket.h> .

       The  uint8_t  and  uint32_t  type  shall  be  defined  as  described in
       <inttypes.h>. Inclusion of the  <netinet/in.h>  header  may  also  make
       visible all symbols from <inttypes.h> and <sys/socket.h>.

       The  <netinet/in.h>  header  shall  define  the  in_addr structure that
       includes at least the following member:

              in_addr_t  s_addr

       The <netinet/in.h> header shall define the sockaddr_in  structure  that
       includes at least the following members (all in network byte order):

              sa_family_t     sin_family   AF_INET.
              in_port_t       sin_port     Port number.
              struct in_addr  sin_addr     IP address.

       The  sockaddr_in  structure is used to store addresses for the Internet
       address family. Values of this type shall be cast  by  applications  to
       struct sockaddr for use with socket functions.

       The  <netinet/in.h>  header  shall  define  the in6_addr structure that
       contains at least the following member:

              uint8_t s6_addr[16]

       This array is used to contain a 128-bit IPv6 address, stored in network
       byte order.

       The  <netinet/in.h> header shall define the sockaddr_in6 structure that
       includes at least the following members (all in network byte order):

              sa_family_t      sin6_family    AF_INET6.
              in_port_t        sin6_port      Port number.
              uint32_t         sin6_flowinfo  IPv6 traffic class and flow information.
              struct in6_addr  sin6_addr      IPv6 address.
              uint32_t         sin6_scope_id  Set of interfaces for a scope.

       The sockaddr_in6 structure shall be set to zero by an application prior
       to  using  it,  since  implementations  are  free  to  have additional,
       implementation-defined fields in sockaddr_in6.

       The sin6_scope_id field is a 32-bit integer that identifies  a  set  of
       interfaces  as  appropriate for the scope of the address carried in the
       sin6_addr field. For a link  scope  sin6_addr,  the  application  shall
       ensure  that sin6_scope_id is a link index. For a site scope sin6_addr,
       the application shall ensure that sin6_scope_id is a  site  index.  The
       mapping  of  sin6_scope_id  to  an  interface  or  set of interfaces is
       implementation-defined.

       The  <netinet/in.h>  header  shall  declare  the   following   external
       variable:

              const struct in6_addr in6addr_any

       This variable is initialized by the system to contain the wildcard IPv6
       address. The <netinet/in.h> header also  defines  the  IN6ADDR_ANY_INIT
       macro.  This  macro must be constant at compile time and can be used to
       initialize a variable of type struct  in6_addr  to  the  IPv6  wildcard
       address.

       The   <netinet/in.h>   header  shall  declare  the  following  external
       variable:

              const struct in6_addr in6addr_loopback

       This variable is initialized by the system to contain the loopback IPv6
       address.     The     <netinet/in.h>    header    also    defines    the
       IN6ADDR_LOOPBACK_INIT macro. This macro must  be  constant  at  compile
       time  and  can be used to initialize a variable of type struct in6_addr
       to the IPv6 loopback address.

       The <netinet/in.h> header shall define  the  ipv6_mreq  structure  that
       includes at least the following members:

              struct in6_addr  ipv6mr_multiaddr  IPv6 multicast address.
              unsigned         ipv6mr_interface  Interface index.

       The  <netinet/in.h> header shall define the following macros for use as
       values of the level argument of getsockopt() and setsockopt():

       IPPROTO_IP
              Internet protocol.

       IPPROTO_IPV6
              Internet Protocol Version 6.

       IPPROTO_ICMP
              Control message protocol.

       IPPROTO_RAW
              Raw IP Packets Protocol.

       IPPROTO_TCP
              Transmission control protocol.

       IPPROTO_UDP
              User datagram protocol.

       The <netinet/in.h> header shall define the following macros for use  as
       destination addresses for connect(), sendmsg(), and sendto():

       INADDR_ANY
              IPv4 local host address.

       INADDR_BROADCAST
              IPv4 broadcast address.

       The  <netinet/in.h>  header  shall  define  the following macro to help
       applications declare buffers of the proper size to store IPv4 addresses
       in string form:

       INET_ADDRSTRLEN
              16. Length of the string form for IP.

       The htonl(), htons(), ntohl(), and ntohs() functions shall be available
       as defined in <arpa/inet.h> . Inclusion of  the  <netinet/in.h>  header
       may also make visible all symbols from <arpa/inet.h> .

       The  <netinet/in.h>  header  shall  define  the following macro to help
       applications declare buffers of the proper size to store IPv6 addresses
       in string form:

       INET6_ADDRSTRLEN
              46. Length of the string form for IPv6.

       The  <netinet/in.h>  header  shall  define  the  following macros, with
       distinct integer values, for use in the  option_name  argument  in  the
       getsockopt() or setsockopt() functions at protocol level IPPROTO_IPV6:

       IPV6_JOIN_GROUP
              Join a multicast group.

       IPV6_LEAVE_GROUP
              Quit a multicast group.

       IPV6_MULTICAST_HOPS

              Multicast hop limit.

       IPV6_MULTICAST_IF
              Interface to use for outgoing multicast packets.

       IPV6_MULTICAST_LOOP

              Multicast packets are delivered back to the local application.

       IPV6_UNICAST_HOPS
              Unicast hop limit.

       IPV6_V6ONLY
              Restrict AF_INET6 socket to IPv6 communications only.

       The  <netinet/in.h>  header shall define the following macros that test
       for special IPv6 addresses. Each macro is  of  type  int  and  takes  a
       single argument of type const struct in6_addr *:

       IN6_IS_ADDR_UNSPECIFIED

              Unspecified address.

       IN6_IS_ADDR_LOOPBACK

              Loopback address.

       IN6_IS_ADDR_MULTICAST

              Multicast address.

       IN6_IS_ADDR_LINKLOCAL

              Unicast link-local address.

       IN6_IS_ADDR_SITELOCAL

              Unicast site-local address.

       IN6_IS_ADDR_V4MAPPED

              IPv4 mapped address.

       IN6_IS_ADDR_V4COMPAT

              IPv4-compatible address.

       IN6_IS_ADDR_MC_NODELOCAL

              Multicast node-local address.

       IN6_IS_ADDR_MC_LINKLOCAL

              Multicast link-local address.

       IN6_IS_ADDR_MC_SITELOCAL

              Multicast site-local address.

       IN6_IS_ADDR_MC_ORGLOCAL

              Multicast organization-local address.

       IN6_IS_ADDR_MC_GLOBAL

              Multicast global address.

       The following sections are informative.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Host   and  Network  Byte  Orders  ,  <arpa/inet.h>  ,  <inttypes.h>  ,
       <sys/socket.h> , the System Interfaces volume of  IEEE Std 1003.1-2001,
       connect(), getsockopt(), htonl(), htons(), ntohl(), ntohs(), sendmsg(),
       sendto(), setsockopt()

COPYRIGHT

       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .