| The final class of network devices is the dial-up | | | | PPPoE packages, like Roaring Penguin. |
| device. Most typically, this is a conventional | | | | PPP is sometimes used on connections that don't |
| telephone modem used in conjunction with the | | | | involve modems. For instance, you can use it to |
| Point-to-Point Protocol (PPP) to establish a | | | | network two computers via their serial ports. |
| connection to the Internet via an ISP. Such | | | | Such configurations are seldom worthwhile with |
| connections are established via command-line or | | | | desktop systems, because Ethernet cards are |
| GUI tools, as described in Chapter 2. In addition to | | | | inexpensive and provide much faster connections. |
| these tools, though, the Linux kernel requires | | | | You might want to use this type of link when |
| support for the dial-up connection. | | | | connecting a desktop system to a palmtop |
| To activate this support, you must select the PPP | | | | computer, though, or for a temporary connection |
| (Point-to-Point Protocol) Support option in the | | | | if you don't want to bother installing network |
| Network Device Support menu. When you select | | | | cards. |
| this option, several suboptions will become | | | | PPP isn't the only type of dial-up connection that |
| available, such as PPP Support for Async Serial | | | | Linux supports. The kernel includes support for |
| Ports and PPP Deflate Compression. These | | | | the older Serial Line Internet Protocol (SLIP), |
| options aren't usually strictly necessary, but | | | | which serves much the same function as PPP. |
| sometimes they can improve a connection, such | | | | SLIP has been largely abandoned by ISPs, so it's |
| as by automatically compressing highly | | | | unlikely you'll need to use it over a modem. A few |
| compressible data like text for higher net | | | | Linux tools use it locally, though; for instance, |
| throughput. The experimental PPP over Ethernet | | | | some types of dial-on-demand utilities (which dial a |
| option is required if you intend to use the kernel's | | | | PPP connection whenever network activity is |
| PPPoE features for some DSL connections, but | | | | detected) use SLIP to detect outgoing connection |
| this option is not required with some add-on | | | | attempts. |