I covered most of the items in the Sharing pane of System Preferences in Chapter 10. However, one that I didn't cover was Printer Sharing. If you have several Macs on a local network, Printer Sharing—which works seamlessly with OS X's Rendezvous technology—is actually quite amazing. When Printer Sharing is enabled on your Mac, any print queue that has been set up for a printer connected to your Mac (either via Print Center or using the CUPS web interface) will be shared with other Macs running OS X. Other Macs will be able to see and print to those printers as if they were actually connected to those Macs. Even better, Printer Sharing doesn't just work with those printers that are officially supported by OS X; if you've installed the Gimp-Print package, for example, to add support for a printer, that printer will also be available to other Macs on your network. And unlike Mac OS 9's similar functionality, USB Printer Sharing, Printer Sharing in OS X works for any printer connected via USB, Ethernet, wireless (AirPort), and even FireWire.
Enabling Printer Sharing is as simple as opening Sharing preferences and checking the box next to Printer Sharing. Other Macs on your network simply need to check "Show printers connected to other computers" in Print Center preferences. Printers shared by your Mac will automatically be set up in Print Center for them. After that they can print to your shared printer as if it was connected to their own computer.
Some OS X system updates replace your CUPS configuration file (/etc/cups/cupsd.conf) with an updated version. The newer version usually has Printer Sharing disabled. This means that if you use Printer Sharing, you'll often have to re-enable it after updating OS X.
Sharing Printers with a Mac Running OS 9 Normally, Macs booted into OS 9 will not be able to access a printer shared by a Mac running OS X. However, you can enable USB Printer Sharing in the Classic Environment, which will allow OS 9 computers to print to a USB printer connected to an OS X computer.
The problem is that, according to Apple, you shouldn't have Printer Sharing in OS X and USB Printer Sharing in the Classic Environment enabled at the same time. For more details, see http://docs.info.apple.com/article.html?artnum=107060.
You may be able to access a shared printer from OS 9 via LPD (an IP-based printing protocol). For details see http://www.macosxhints.com/article.php?story=20020901005320524.
Sharing Printers with Windows Computers If you enable Printer Sharing and Windows File Sharing in Sharing preferences, Windows computers on your local network will also be able to access your shared printers. However, instead of using Windows' Add Printer Wizard, Windows users should go to Network Neighborhood and locate your computer. If they open your computer's icon, any printers being shared by your Mac should be visible. They can right-click on one of them and select Install to print to it (although they will have to have the appropriate driver installed on their Windows computer).
Sharing Printers over the Internet If you'd like to—or would like someone else to—be able to print to a shared printer from elsewhere on the Internet (or from a different subnet of the same network), you can do so using IPP (Internet Protocol Printing). Here's how you do this from another Mac running OS X.
From your Mac (the one sharing the printer), open the CUPS web interface in your browser. Go to Manage Printers, and then click on the printer you wish to access. Note the URL in your web browser's address field. (For example, for my Samsung laser printer, the address is http://127.0.0.1:631/printers/ML_1210.)
From the other Mac (the one you want to use to print to your shared printer), launch Print Center and access the Advanced Add Printer dialog (hold down the option key and click the Add toolbar item, then select Advanced from the pop-up menu).
In the Advanced dialog select "Internet Printing Protocol (http)" from the Device pop-up menu. Enter a name for the printer in the Device Name field, and then enter the address of the printer in the Device URI field. However, in the address you noted above, replace 127.0.0.1 with the actual IP address of the computer sharing the printer. Then, select the correct printer brand and model in the Printer Model section. Click Add to add the printer.
Assuming that both computers are connected to the Internet, you should be able to print over the Internet by simply selecting the new printer in print dialogs.
If the computer sharing the printer is behind a firewall and/or router, remember the caveats I explained in Chapter 10 about IP addresses.