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In the Novell NetWare world, a socket is part of an IPX internetwork address and acts as a destination for the IPX data packet. Most socket numbers are allocated dynamically, but a few are associated with specific functions.

Sockets were first developed as a part of the BSD Unix system kernel, in which they allow processes that are not running at the same time or on the same system to exchange information. You can read data from or write data to a socket just as you can do with a file. Socket pairs are bidirectional so that either process can send data to the other.

Understanding IP Addressing

As you know from “The Internet Protocol” section earlier in this chapter, IP moves data between computer systems in the form of a datagram, and each datagram is delivered to the destination port number that is contained in the datagram header. This destination port number, or address, is a standard 16-bit number that contains enough information to identify the receiving network and the specific host on that network for which the datagram is intended.

In this section, you’ll learn what IP addresses are, why they are so necessary, and how they are used in TCP/IP networking. But first, let’s clear up a possible source of confusion: Ethernet addresses and IP addresses.

Ethernet Addresses Explained

You may remember from an earlier section that TCP/IP is independent of the underlying network hardware. If you are running on an Ethernet-based network, be careful not to confuse the Ethernet hardware address and the IP address required by TCP/IP.

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