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.\" @(#)inet.4 6.6 (Berkeley) 3/28/91
.Nd Internet protocol family
.Fd #include <sys/types.h>
.Fd #include <netinet/in.h>
The Internet protocol family is a collection of protocols
transport layer, and utilizing the Internet address format.
The Internet family provides protocol support for the
.Dv SOCK_STREAM , SOCK_DGRAM ,
interface provides access to the
Internet addresses are four byte quantities, stored in
network standard format (on the
reversed). The include file
as a discriminated union.
Sockets bound to the Internet protocol family utilize
the following addressing structure,
.Bd -literal -offset indent
Sockets may be created with the local address
matching on incoming messages.
The distinguished address
is allowed as a shorthand for the broadcast address on the primary
network if the first network configured supports broadcast.
The Internet protocol family is comprised of
transport protocol, Internet Control
and User Datagram Protocol
abstraction. A raw interface to
by creating an Internet socket of type
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
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
Internet may chose to use a single network number for the cluster;
this is done by using subnet addressing.
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
commands on a datagram socket in the Internet domain;
they have the same form as the
.Bl -tag -width 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,
Get interface network mask.
.%T "An Introductory 4.3 BSD Interprocess Communication Tutorial"
.%T "An Advanced 4.3 BSD Interprocess Communication Tutorial"
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
protocol interface appeared in