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.
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.
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
networks) and AX.25, NetRom, and Rose (for amateur radio networks). Other standard Net-4 features
include IP firewalling, IP accounting and IP Masquerade
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 filesystem, which interoperates with applications like
lanmanager
and Microsoft Windows, called Samba, written by Andrew Tridgell, and an implementation
of the Novell NCP (NetWare Core Protocol).
of the Novell NCP (NetWare Core Protocol).
Different Streaks of Development
There have been, at various times, varying network development efforts active for Linux.
Fred continued development after Net-2Debugged was made the official network implementation. This
development led to the Net-2e, which featured a much revised design of the networking layer. Fred was
working toward a standardized Device Driver Interface (DDI), but the Net-2e work has ended now.
Yet another implementation of TCP/IP networking came from Matthias Urlichs, who wrote an ISDN
driver for Linux and FreeBSD. For this driver, he integrated some of the BSD networking code in the
Linux kernel. That project, too is no longer being worked on.
There has been a lot of rapid change in the Linux kernel networking implementation, and change is still
the watchword as development continues. Sometimes this means that changes also have to occur in other
software, such as the network configuration tools. While this is no longer as large a problem as it once
was, you may still find that upgrading your kernel to a later version means that you must upgrade your
network configuration tools, too. Fortunately, with the large number of Linux distributions available
today, this is a quite simple task.
The Net-4 network implementation is now quite mature and is in use at a very large number of sites
around the world. Much work has been done on improving the performance of the Net-4 implementation,
and it now competes with the best implementations available for the same hardware platforms. Linux is
proliferating in the Internet Service Provider environment, and is often used to build cheap and reliable
World Wide Web servers, mail servers, and news servers for these sorts of organizations. There is now
sufficient development interest in Linux that it is managing to keep abreast of networking technology as
it changes, and current releases of the Linux kernel offer the next generation of the IP protocol, IPv6, as a
standard offering.
Fred continued development after Net-2Debugged was made the official network implementation. This
development led to the Net-2e, which featured a much revised design of the networking layer. Fred was
working toward a standardized Device Driver Interface (DDI), but the Net-2e work has ended now.
Yet another implementation of TCP/IP networking came from Matthias Urlichs, who wrote an ISDN
driver for Linux and FreeBSD. For this driver, he integrated some of the BSD networking code in the
Linux kernel. That project, too is no longer being worked on.
There has been a lot of rapid change in the Linux kernel networking implementation, and change is still
the watchword as development continues. Sometimes this means that changes also have to occur in other
software, such as the network configuration tools. While this is no longer as large a problem as it once
was, you may still find that upgrading your kernel to a later version means that you must upgrade your
network configuration tools, too. Fortunately, with the large number of Linux distributions available
today, this is a quite simple task.
The Net-4 network implementation is now quite mature and is in use at a very large number of sites
around the world. Much work has been done on improving the performance of the Net-4 implementation,
and it now competes with the best implementations available for the same hardware platforms. Linux is
proliferating in the Internet Service Provider environment, and is often used to build cheap and reliable
World Wide Web servers, mail servers, and news servers for these sorts of organizations. There is now
sufficient development interest in Linux that it is managing to keep abreast of networking technology as
it changes, and current releases of the Linux kernel offer the next generation of the IP protocol, IPv6, as a
standard offering.
Where to Get the Code
It seems odd now to remember that in the early days of the Linux network code development, the
standard kernel required a huge patch kit to add the networking support to it. Today, network
development occurs as part of the mainstream Linux kernel development process. The latest stable Linux
kernels can be found on
standard kernel required a huge patch kit to add the networking support to it. Today, network
development occurs as part of the mainstream Linux kernel development process. The latest stable Linux
kernels can be found on
ftp.kernel.org in /pub/linux/kernel/v2.x/, where x is an even number.
The latest experimental Linux kernels can be found on ftp.kernel.org in
The latest experimental Linux kernels can be found on ftp.kernel.org in
/pub/linux/kernel/v2.y/
, where y is an odd number. There are Linux kernel source mirrors all
over the world. It is now hard to imagine Linux without standard network support.
over the world. It is now hard to imagine Linux without standard network support.
Linear Mode
