Some popular networking protocols from the Introduction to Linux by OnWorks

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It's really much more complicated

The above and following sections are included because you will come across some networking terms sooner or later; they will give you some starting points, should you want to find out about the details.

10.1.2. Some popular networking protocols

Linux supports many different networking protocols. We list only the most important:

10.1.2.1. TCP/IP

The Transport Control Protocol and the Internet Protocol are the two most popular ways of communicating on the Internet. A lot of applications, such as your browser and E-mail program, are built on top of this protocol suite.

Very simply put, IP provides a solution for sending packets of information from one machine to another, while TCP ensures that the packets are arranged in streams, so that packets from different applications don't get mixed up, and that the packets are sent and received in the correct order.

A good starting point for learning more about TCP and IP is in the following documents:

• man 7 ip: Describes the IPv4 protocol implementation on Linux (version 4 currently being the most wide-spread edition of the IP protocol).

• man 7 tcp: Implementation of the TCP protocol.

• RFC793, RFC1122, RFC2001 for TCP, and RFC791, RFC1122 and RFC1112 for IP.

The Request For Comments documents contain the descriptions of networking standards, protocols, applications and implementation. These documents are managed by the Internet Engineering Task Force, an international community concerned with the smooth operation of the Internet and the evolution and development of the Internet architecture.

Your ISP usually has an RFC archive available, or you can browse the RFCs via http://www.ietf.org/rfc.html.

10.1.2.2. TCP/IPv6

Nobody expected the Internet to grow as fast as it does. IP proved to have quite some disadvantages when a really large number of computers is in a network, the most important being the availability of unique addresses to assign to each machine participating. Thus, IP version 6 was deviced to meet the needs of today's Internet.

Unfortunately, not all applications and services support IPv6, yet. A migration is currently being set in motion in many environments that can benefit from an upgrade to IPv6. For some applications, the old protocol is still used, for applications that have been reworked the new version is already active. So when checking your network configuration, sometimes it might be a bit confusing since all kinds of measures can be taken to hide one protocol from the other so as the two don't mix up connections.

More information can be found in the following documents:

• man 7 ipv6: the Linux IPv6 protocol implementation.

• RFC1883 describing the IPv6 protocol.

10.1.2.3. PPP, SLIP, PLIP, PPPOE

The Linux kernel has built-in support for PPP (Point-to-Point-Protocol), SLIP (Serial Line IP), PLIP (Parallel Line IP) and PPPP Over EThernet. PPP is the most popular way individual users access their ISP (Internet Service Provider), although in densely populated areas it is often being replaced by PPPOE, the protocol used for ADSL (Asymmetric Digital Subscriber Line) connections.

Most Linux distributions provide easy-to-use tools for setting up an Internet connection. The only thing you basically need is a username and password to connect to your Internet Service Provider (ISP), and a telephone number in the case of PPP. These data are entered in the graphical configuration tool, which will likely also allow for starting and stopping the connection to your provider.

10.1.2.4. ISDN

The Linux kernel has built-in ISDN capabilities. Isdn4linux controls ISDN PC cards and can emulate a modem with the Hayes command set ("AT" commands). The possibilities range from simply using a terminal program to full connection to the Internet.

Check your system documentation.

10.1.2.5. AppleTalk

Appletalk is the name of Apple's internetworking stack. It allows a peer-to-peer network model which provides basic functionality such as file and printer sharing. Each machine can simultaneously act as a client and a server, and the software and hardware necessary are included with every Apple computer.

Linux provides full AppleTalk networking. Netatalk is a kernel-level implementation of the AppleTalk Protocol Suite, originally for BSD-derived systems. It includes support for routing AppleTalk, serving UNIX and AFS file systems using AppleShare and serving UNIX printers and accessing AppleTalk printers.

10.1.2.6. SMB/NMB

For compatibility with MS Windows environments, the Samba suite, including support for the NMB and SMB protocols, can be installed on any UNIX-like system. The Server Message Block protocol (also called Session Message Block, NetBIOS or LanManager protocol) is used on MS Windows 3.11, NT, 95/98, 2K and XP to share disks and printers.

The basic functions of the Samba suite are: sharing Linux drives with Windows machines, accessing SMB shares from Linux machines, sharing Linux printers with Windows machines and sharing Windows printers

with Linux machines.

Most Linux distributions provide a samba package, which does most of the server setup and starts up smbd, the Samba server, and nmbd, the netbios name server, at boot time by default. Samba can be configured graphically, via a web interface or via the command line and text configuration files. The daemons make a Linux machine appear as an MS Windows host in an MS Windows My Network Places/Network Neighbourhood window; a share from a Linux machine will be indistinguishable from a share on any other host in an MS Windows environment.

More information can be found at the following locations:

• man smb.conf: describes the format of the main Samba configuration file.

• The Samba Project Documentation (or check your local samba.org mirror) contains an easy to read installation and testing guide, which also explains how to configure your Samba server as a Primary Domain Controller. All the man pages are also available here.