INET(3) 		   Linux Programmer's Manual		       INET(3)



NAME
       inet_aton,    inet_addr,    inet_network,   inet_ntoa,	inet_makeaddr,
       inet_lnaof, inet_netof - Internet address manipulation routines

SYNOPSIS
       #include <sys/socket.h>
       #include <netinet/in.h>
       #include <arpa/inet.h>

       int inet_aton(const char *cp, struct in_addr *inp);

       in_addr_t inet_addr(const char *cp);

       in_addr_t inet_network(const char *cp);

       char *inet_ntoa(struct in_addr in);

       struct in_addr inet_makeaddr(int net, int host);

       in_addr_t inet_lnaof(struct in_addr in);

       in_addr_t inet_netof(struct in_addr in);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       inet_aton(), inet_ntoa(): _BSD_SOURCE || _SVID_SOURCE

DESCRIPTION
       inet_aton() converts the Internet host address  cp  from  the  standard
       numbers-and-dots  notation into binary data and stores it in the struc-
       ture that inp points to.  inet_aton() returns nonzero if the address is
       valid, zero if not.

       The  inet_addr()  function  converts  the Internet host address cp from
       numbers-and-dots notation into binary data in network byte  order.   If
       the input is invalid, INADDR_NONE (usually -1) is returned.  This is an
       obsolete interface to inet_aton(), described immediately above;	it  is
       obsolete   because   -1	is  a  valid  address  (255.255.255.255),  and
       inet_aton() provides a cleaner way to indicate error return.

       The inet_network() function extracts a number in host byte order  suit-
       able  for use as an Internet address from cp, which is a string in num-
       bers-and-dots notation.	If the input is invalid, -1 is returned.

       The inet_ntoa() function converts the Internet host address in given in
       network	byte  order to a string in standard numbers-and-dots notation.
       The string is returned in a statically allocated buffer,  which	subse-
       quent calls will overwrite.

       The  inet_makeaddr() function makes an Internet host address in network
       byte order by combining the network number net with the	local  address
       host in network net, both in local host byte order.

       The  inet_lnaof()  function  returns the local host address part of the
       Internet address in.  The local host address is returned in local  host
       byte order.

       The inet_netof() function returns the network number part of the Inter-
       net Address in.	The network number is  returned  in  local  host  byte
       order.

       The   structure	 in_addr  as  used  in	inet_ntoa(),  inet_makeaddr(),
       inet_lnaof() and inet_netof() is defined in <netinet/in.h> as:

	   typedef uint32_t in_addr_t;

	   struct in_addr {
	       in_addr_t s_addr;
	   };

       Note that on the i386 the host byte order  is  Least  Significant  Byte
       first  (little  endian), whereas the network byte order, as used on the
       Internet, is Most Significant Byte first (big endian).

CONFORMING TO
       4.3BSD.	inet_addr(), inet_aton(), and  inet_ntoa()  are  specified  in
       POSIX.1-2001.

NOTES
       When  you  using numbers-and-dots notation for addresses, be aware that
       each number will be interpreted as octal if preceded by a 0 and as hex-
       adecimal  if preceded by 0x.  For example, inet_aton("226.000.000.037",
       &t) will interpret the address as 226.0.0.31 and not 226.0.0.37.

SEE ALSO
       gethostbyname(3), getnetent(3), inet_ntop(3),  inet_pton(3),  hosts(5),
       networks(5)

COLOPHON
       This  page  is  part of release 2.77 of the Linux man-pages project.  A
       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.



GNU				  2007-07-26			       INET(3)