Provided by: manpages-posix-dev_2013a-2_all bug

PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of
       this interface may differ (consult the corresponding Linux  manual  page  for  details  of
       Linux behavior), or the interface may not be implemented on Linux.

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 described in <inttypes.h>.

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

       The   <netinet_in.h>   header   shall   define   the  sa_family_t  type  as  described  in
       <sys/socket.h>.

       The <netinet_in.h> header shall define the uint8_t and  uint32_t  types  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, which shall include at least
       the following member:

           in_addr_t  s_addr

       The  <netinet/in.h>  header shall define the sockaddr_in structure, which shall include at
       least the following members:

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

       The sin_port and sin_addr members shall be in network byte order.

       The sockaddr_in structure is used to store addresses  for  the  Internet  address  family.
       Pointers  to  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,  which  shall  include  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, which shall include at
       least the following members:

           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 sin6_port and sin6_addr members shall be in network byte order.

       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,  which  shall  include  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 symbolic constants 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  symbolic  constants  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 symbolic constant, with the value
       specified, 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 described 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 symbolic constant, with the value
       specified, 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 symbolic constants, 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

       Section 4.9, Host and Network Byte Orders, <arpa_inet.h>, <inttypes.h>, <sys_socket.h>

       The System Interfaces volume of POSIX.1‐2008, connect(), getsockopt(), htonl(), sendmsg(),
       sendto(), setsockopt()

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2013  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013  by  the
       Institute  of  Electrical  and  Electronics  Engineers,  Inc and The Open Group.  (This is
       POSIX.1-2008 with the  2013  Technical  Corrigendum  1  applied.)  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.unix.org/online.html .

       Any  typographical  or  formatting errors that appear in this page are most likely to have
       been introduced during the conversion of the source files to man page  format.  To  report
       such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .