INET(4F)                 Series 300 Only                 INET(4F)

     NAME
          inet - Internet protocol family

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

     HP-UX COMPATIBILITY
          Level:    HP-UX/NON-STANDARD

          Origin:   UCB

          Remarks:  Implemented on the Series 300 only.

     DESCRIPTION
          The internet protocol family is a collection of protocols
          layered atop 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 a discriminated
          union, called ``struct in_addr''.

          Sockets bound to the Internet protocol family utilize an
          addressing structure called ``struct sockaddr_in''.
          Pointers to this structure may 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 should always be set to be
          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, will not interfere with creating a UDP socket and
          also binding it to local port number 10000 at the same time.

     Hewlett-Packard               - 1 -             (printed 7/16/86)

     INET(4F)                 Series 300 Only                 INET(4F)

     SEE ALSO
          tcp(4P), udp(4P).

     Hewlett-Packard               - 2 -             (printed 7/16/86)