Index for Section 7

Alphabetical listing for I

inet(7)
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 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.

  Internet addresses are 4-byte quantities, stored in network standard format
  (on the VAX and other machines, these are word and byte reversed).  The
  netinet/in.h include file defines this address as a discriminated union.

  Sockets bound to the Internet protocol family utilize an addressing
  structure sockaddr_in, whose format is dependent on whether _SOCKADDR_LEN
  has been defined prior to including the netinet/in.h header file.  If
  _SOCKADDR_LEN is defined, the sockaddr_in structure takes 4.4BSD behavior,
  with a separate field for specifying the length of the address;  otherwise,
  the default 4.3BSD behavior is used.

  Sockets may be created with the local address INADDR_ANY to effect wildcard
  matching on incoming messages.  The address in a connect() or sendto() 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.

  The Internet protocol family is comprised of the IP transport protocol,
  Internet Control Message Protocol (ICMP), 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.  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() commands
  on a datagram socket in the Internet domain; they have the same form as the
  SIOCSIFADDR command (see the reference page for the netintro function).


  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.

NOTES
  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.

RELATED INFORMATION
  Functions: ioctl(2), socket(2)

  Network Information: netintro(7), tcp(7), udp(7), ip(7), icmp(7)

  Technical Overview