FreeBSD® Unleashed

IP Addresses

If you've ever done anything on the Internet at all, you're probably familiar with IP addresses—at least enough to know what they look like. An IP address is typically used as a way to refer to a specific computer on the Internet, though its meaning is actually a lot more flexible than “one IP address per machine.” Most generally, it's a logical designation whose purpose is to locate a machine on the Internet so that IP routers can direct traffic between it and any other machine.

An IP address is a string of 32 bits in the IP header, which specifies either what machine a packet came from or where it is destined (both addresses are present in the header). The 32 bits can be thought of also as four 8-bit bytes, each of which is expressed ...