NAME
inet — Internet protocol family
SYNOPSIS
#include <sys/types.h>
#include <netinet/in.h>
DESCRIPTION
The internet protocol family is a collection of protocols
layered on top of the
Internet Protocol
(IP) network layer, which utilizes the internet address format.
The internet family supports the
SOCK_STREAM and SOCK_DGRAM socket types.
Addressing
Internet addresses are four byte entities.
The include file
<netinet/in.h>
defines this address as the structure
struct in_addr.
Sockets bound to the internet protocol family
utilize an addressing structure called
struct sockaddr_in.
Pointers to this structure can be used in system calls
wherever they ask for a pointer to a
struct sockaddr.
There are three fields of interest within this structure.
The first is
sin_family,
which must be set to AF_INET.
The next is
sin_port,
which specifies the port number to be used on the desired host.
The third is
sin_addr,
which is of type
struct in_addr,
and specifies the address of the desired host.
Protocols
The internet protocol family is comprised of the
IP
network protocol,
Internet Control Message Protocol
(ICMP),
Transmission Control Protocol
(TCP),
and User Datagram Protocol
(UDP).
TCP
is used to support the
SOCK_STREAM
socket type while
UDP
is used to support the
SOCK_DGRAM
socket type.
The
ICMP
message protocol and
IP
network protocol are not directly accessible.
The local port address is selected from independent domains for
TCP
and
UDP
sockets.
This means that creating a
TCP
socket and binding it to local port number 10000, for example,
does not interfere with creating a
UDP
socket and also binding it to local port number 10000 at the same time.
Port numbers in the range 1-1023 inclusive are reserved
for use by the super-user only.
Attempts to bind to port numbers in this range
by non-super-users fail and result in an error returned.
AUTHOR
inet
was developed by the University of California, Berkeley.
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