INET(7F)							      INET(7F)

NAME    [Toc]    [Back]

     inet - Internet protocol family

SYNOPSIS    [Toc]    [Back]

     #include <sys/types.h>
     #include <netinet/in.h>

DESCRIPTION    [Toc]    [Back]

     The Internet protocol family is a collection of protocols layered atop
     the Internet Protocol (IP)	transport layer, and utilizing the Internet
     address format.  The Internet family provides protocol support for	the
     SOCK_STREAM, SOCK_DGRAM, and SOCK_RAW socket types; the SOCK_RAW
     interface provides	access to the IP protocol.

ADDRESSING    [Toc]    [Back]

     Internet addresses	are four byte quantities, stored in network standard
     format.  The include file <netinet/in.h> defines this address as a
     discriminated union.

     Sockets bound to the Internet protocol family utilize the following
     addressing	structure:

     struct sockaddr_in	{
	    short     sin_family;
	    u_short   sin_port;
	    struct    in_addr sin_addr;
	    char      sin_zero[8];
     };

     Sockets may be created with the local address INADDR_ANY to effect
     "wildcard"	matching on incoming messages. The address in a	connect(2) or
     sendto(2) call may	be given as INADDR_ANY to mean ``this host.''  The
     distinguished address INADDR_BROADCAST is allowed as a shorthand for the
     broadcast address on the primary network if the first network configured
     supports broadcast.

PROTOCOLS    [Toc]    [Back]

     The Internet protocol family is comprised of the IP transport protocol,
     Internet Control Message Protocol (ICMP), Internet	Group Management
     Protocol (IGMP), Transmission Control Protocol (TCP), and User Datagram
     Protocol (UDP).  TCP is used to support the SOCK_STREAM abstraction while
     UDP is used to support the	SOCK_DGRAM abstraction.	 A raw interface to IP
     is	available by creating an Internet socket of type SOCK_RAW.  The	ICMP
     message protocol is accessible from a raw socket.

     The 32-bit	Internet address contains both network and host	parts.	It is
     frequency-encoded;	the most-significant bit is clear in Class A
     addresses,	in which the high-order	8 bits are the network number.	Class
     B addresses use the high-order 16 bits as the network field, and Class C
     addresses have a 24-bit network part.  Sites with a cluster of local
     networks and a connection to the DARPA Internet may chose to use a	single
     network number for	the cluster; this is done by using subnet addressing.



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INET(7F)							      INET(7F)



     The local (host) portion of the address is	further	subdivided into	subnet
     and host parts.  Within a subnet, each subnet appears to be an individual
     network; externally, the entire cluster appears to	be a single, uniform
     network requiring only a single routing entry.  Subnet addressing is
     enabled and examined by the following ioctl(2) commands on	a datagram
     socket in the Internet domain; they have the same form as the SIOCIFADDR
     command (see netintro(7)).

     SIOCSIFNETMASK	 Set interface network mask.  The network mask defines
			 the network part of the address; if it	contains more
			 of the	address	than the address type would indicate,
			 then subnets are in use.

     SIOCGIFNETMASK	 Get interface network mask.

SEE ALSO    [Toc]    [Back]

     ioctl(2), socket(2), netintro(7), route(7F), tcp(7P), udp(7P), ip(7P),
     icmp(7P)
     IRIX Network Programming Guide.

CAVEAT    [Toc]    [Back]

     The Internet protocol support is subject to change	as the Internet
     protocols develop.	 Users should not depend on details of the current
     implementation, but rather	the services exported.


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