Other commonly used ports are listed in Appendix B.
Windows and some applications typically leave more ports
open than you probably need, potentially making your PC
vulnerable to spyware, pop ups, viruses, intruders, and other
annoyances. See ???Secure Your Networked PC,??? later in this
chapter, for the solution.
IP addresses
An IP address is a set of four numbers (e.g., 207.46.230.218) that corresponds
to a single computer or device on a TCP/IP-based network. Each
element of the address can range from 0 to 255, providing 2564 or
nearly 4.3 billion possible combinations. On the Internet, dedicated
Build Your Network | 345
Networking and
Internet
machines called domain name servers are used to translate named hosts,
such as www.microsoft.com, to their respective numerical IP addresses
and back again.
No two computers on a single network can have the same IP
address, but a single computer can have multiple IP
addresses (one for each network to which it??™s connected). A
router, discussed later in this chapter, does allow multiple
PCs to share a single Internet connection (and thus a single
IP address), but only by creating a separate network (LAN)
and acting as a gateway between them.
To connect two different networks to each other, while still maintaining
two separate sets of IP addresses, you??™ll need either a bridge or a
router. Provided that you install two network adapters in your PC, Windows
can act as an impromptu bridge; just highlight two connections in
your Network Connections window (discussed later in this chapter),
right-click, and select Bridge Connections.
Pages:
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493