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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 .