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(libc.info)Internet Namespace

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The Internet Namespace
======================

   This section describes the details of the protocols and socket naming
conventions used in the Internet namespace.

   Originally the Internet namespace used only IP version 4 (IPv4).
With the growing number of hosts on the Internet, a new protocol with a
larger address space was necessary: IP version 6 (IPv6).  IPv6
introduces 128-bit addresses (IPv4 has 32-bit addresses) and other
features, and will eventually replace IPv4.

   To create a socket in the IPv4 Internet namespace, use the symbolic
name `PF_INET' of this namespace as the NAMESPACE argument to `socket'
or `socketpair'.  For IPv6 addresses you need the macro `PF_INET6'.
These macros are defined in `sys/socket.h'.

 - Macro: int PF_INET
     This designates the IPv4 Internet namespace and associated family
     of protocols.

 - Macro: int PF_INET6
     This designates the IPv6 Internet namespace and associated family
     of protocols.

   A socket address for the Internet namespace includes the following
components:

   * The address of the machine you want to connect to.  Internet
     addresses can be specified in several ways; these are discussed in
     Note: Internet Address Formats, Note: Host Addresses and Note:
     Host Names.

   * A port number for that machine.  Note: Ports.

   You must ensure that the address and port number are represented in a
canonical format called "network byte order".  Note: Byte Order, for
information about this.

Internet Address Formats

How socket addresses are specified in the

Internet namespace.

Host Addresses

All about host addresses of Internet host.

Protocols Database

Referring to protocols by name.

Ports

Internet port numbers.

Services Database

Ports may have symbolic names.

Byte Order

Different hosts may use different byte

ordering conventions; you need to canonicalize host address and port number.

Inet Example

Putting it all together.