Linux Networking

As it is the result of a concerted effort of programmers around the world, Linux wouldn't have been possible without the global network. So it's not surprising that in the early stages of development, several people started to work on providing it with network capabilities. A UUCP implementation was running on Linux almost from the very beginning, and work on TCP/IP-based networking started around autumn 1992, when Ross Biro and others created what has now become known as Net-1.
After Ross quit active development in May 1993, Fred van Kempen began to work on a new implementation, rewriting major parts of the code. This project was known as Net-2. The first public release, Net-2d, was made in the summer of 1993 (as part of the 0.99.10 kernel), and has since been maintained and expanded by several people, most notably Alan Cox. Alan's original work was known as Net-2Debugged. After heavy debugging and numerous improvements to the code, he changed its name to Net-3 after Linux 1.0 was released. The Net-3 code was further developed for Linux 1.2 and Linux 2.0. The 2.2 and later kernels use the Net-4 version network support, which remains the standard official offering today.

The Net-4 Linux Network code offers a wide variety of device drivers and advanced features. Standard Net-4 protocols include SLIP and PPP (for sending network traffic over serial lines), PLIP (for parallel lines), IPX (for Novell compatible networks, which we'll discuss in Chapter 15, IPX and the NCP Filesystem), Appletalk (for Apple networks) and AX.25, NetRom, and Rose (for amateur radio networks). Other standard Net-4 features include IP firewalling, IP accounting (discussed later in Chapter 9, TCP/IP Firewall and Chapter 10, IP Accounting), and IP Masquerade (discussed later in Chapter 11, IP Masquerade
and Network Address Translation. IP tunnelling in a couple of different flavors and advanced policy routing are supported. A very large variety of Ethernet devices is supported, in addition to support for some FDDI, Token Ring, Frame Relay, and ISDN, and ATM cards.
Additionally, there are a number of other features that greatly enhance the flexibility of Linux. These features include an implementation of the SMB.