10.1.1. Networking protocols
A protocol is, simply put, a set of rules for communication.
Linux supports many different networking protocols. We list only the most important:
10.1.1.1. 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.
The Internet was originally developed three decades ago for the United States Department of Defense (DoD), mainly for the purpose of interconnecting different-brand computers. Another reason for the development of TCP/IP was to provide a reliable data transport system over an unreliable network.
TCP/IP networking has been present in Linux since its beginnings. It has been implemented from scratch. It is one of the most robust, fast and reliable implementations and is one of the key factors of the success of Linux. Linux and networking are made for each other, in so much that not connecting your Linux system to the network may result in slow startup and other troubles. Even if you don't use any network connections to other computers, networking protocols are used for internal system and application communications. Linux expects to be networked.
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 .
10.1.1.2. 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.
10.1.1.3. PPP, SLIP, PLIP, PPPOE
The Linux kernel has built-in support for PPP (Point-to-Point-Protocol), SLIP (Serial Line IP) and PLIP (Parallel Line IP). 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, PPP over Ethernet, the protocol used in cable modem 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
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