Local Area Networking with Mac OS X

Wherever there is more than one computer (whether those machines are running the Mac OS, Windows, Linux, and so on) in the same general physical area, there is an opportunity to network those computers into a local area network (LAN). A LAN offers many benefits, including the following:

  • Sharing devices, such as printers

  • Sharing files

  • Providing a local Web

  • Sharing an Internet connection

  • Providing FTP, email, and other services

A LAN can be as simple as two Macs (or a Mac and a network device such as a printer) connected together using an Ethernet crossover cable. And a LAN can be as complex as hundreds of computers, dozens of printers, and many other devices. Local networks can also be anything in between, from a small home office with a couple of Macs and a Windows machine to a workgroup that has 10 or more workstations in it.

Creating and managing a large Ethernet network (such as one with hundreds of devices on it) is a major task, coverage of which is beyond the scope of this book. This chapter assumes a more modest network that includes several Macs; a Windows PC or two; and a couple of network devices, such as printers. Not coincidentally, this is the environment in which Macs are most likely to be used. The principles of managing larger networks are the same, but the details are much more complicated.

Similarly, this chapter focuses on the two networking technologies for which support is built in to the Mac OS: Ethernet and AirPort. There are other means of networking machines together, but they are specialized and beyond the scope of this book. For most networks that you will manage with Mac OS X, Ethernet and AirPort are the best tools to create a LAN.

Networking Services Supported by Mac OS X

More than any previous version of the Mac OS, Mac OS X supports a variety, in both range and depth, of network services. The network services supported by Mac OS X are summarized in Table 26.1.

Table 26.1. Networking Services Provided by Mac OS X




Apple File Protocol


Enables file sharing on machines running older versions of the Mac OS, such as Mac OS 8 and Mac OS 9.



Set of services used to communicate on Macs running older versions of the Mac OS or AppleTalk devices such as printers. AppleTalk continues to be supported under Mac OS X.



Enables Macs to communicate with various wireless devices, such as cell phones and PDAs.

Bootstrap Protocol



Common Internet File System


Provides remote file access on many play forms, such as Windows.

Dynamic Host Configuration Protocol


Providesautomatic assignment of IP addresses to devices on a network.

File Transfer Protocol


Enables the fast transfer of files over TCP/IP networks.

Hypertext Transport Protocol


Provides the transmission and translation of data between a Web server and Web client.

Internet Protocol


Enables communication across a wide variety of devices and services.

Lightweight Directory Access Protocol


Enables users to locate resources, such as files and hardware devices, on a network.

Network File Service


Enables file sharing on Unix-compatible devices, such as Mac OS X computers.

Network Time Protocol


Synchronizes time across devices on a network.

Open Transport


Another set of networking protocols that was introduced under earlier versions of the Mac OS.

Point-to-Point Protocol


Provides TCP/IP services over dial-up connections (PPP) and over Ethernet (PPPoE).

Printer Access Protocol


Provides services necessary to print to network printers.



Enables Rendezvous-compatible devices on a network, such as computers and printers, to automatically discover and configure other Rendezvous-compatible devices.

Service Location Protocol


Enables devices on a network to be discovered automatically.

Short Message Block


Enables Macs to connect to Windows and Unix file servers.

Transmission Control Protocol/Internet Protocol; User Datagram Protocol/Internet Protocol


Enables the transmission of data across extended networks, such as the Internet. These protocols do not provide services in themselves but are the means by which data is transmitted across networks.

Web-based Distributed Authoring and Versioning


Extends HTTP to provide collaboration and file management on remote Web servers.


Support for SMB and CIFS enables you to integrate Macs onto Windows and Unix networks with no additional software installations. If you have ever been treated as a second-class citizen by a Windows network administrator, this feature alone makes Mac OS X a great thing.

All the services listed in Table 26.1 can be useful, but covering all of them is beyond the scope of this book. In this chapter, you will learn how to implement the two services you are most likely to use: file sharing and FTP. After you have learned to configure these, you can apply similar principles to configure additional services on your network.

To learn how to configure Mac OS X's built-in Web server to implement HTTP services, see "Using Mac OS X to Serve Web Pages," p. 446.


The WebDAV standard is a relatively new one that is gaining wide use. It provides a much better environment for file sharing and other services across HTTP networks, primarily the Web. For example, when you use an iDisk under Mac OS X, you are using the WebDAV standard. This enables you to remain connected to the iDisk for long periods of time without being disconnected during idle periods.

Implementing a Network

To implement a network, you should do the following:

  1. Design your network.

  2. Build your network.

  3. Configure the services that will be available on the network.

  4. Monitor and administer your network.

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