Enabling Multiple Macs to Use a Single Internet Account

One of the primary advantages of networking computers together is that they can share a single Internet account. This is especially useful for broadband accounts; however, you can share a dial-up connection, too.


Dial-up accounts are relatively slow. Supplying several computers through slow access will divide that limited bandwidth and make the already-slow access even slower.

You can also share a single Internet account on mixed networks that include both Macintosh and Windows computers.

Most means of sharing an Internet account rely on the Dynamic Host Configuration Protocol (DHCP). This protocol enables IP addresses to be dynamically assigned to each device on a network. A DHCP server assigns and manages these addresses. This protocol means that each device doesn't have to have a unique IP address; the DHCP server has a unique address and assigns IP addresses to the machines under it, as they are needed.


Each device for which a DHCP server provides an address must have a unique IP address; the DHCP server provides these addresses and ensures that they are unique. Most DHCP servers also provide network address translation (NAT) protection for the devices to which they provide services. When NAT protection is active, all the machines under the server appear to be from one IP address, which is that of the DHCP server. Using a DHCP server with NAT isolates the machines it serves from direct contact with other machines on the Internet and protects those machines from Internet attacks to a great degree.

In this chapter, you will learn how to share an Internet account using the following techniques:

  • AirPort

  • Mac OS X's built-in Internet sharing feature

  • Multiple IP addresses for a single account

  • A hardware DHCP server/hub

    Part I: Mac OS X: Exploring the Core
    Part III: Mac OS X: Living the Digital Life