The 3 modes of use generic described above illustrate the developments consecutive all-round development of the Internet. As applications “natives” of Internet services (domain names, mail, forums, Web, etc..) Are integrated into the system free GNU / Linux it is natural that occupies a prominent place on servers. What about the other important part of this system: the kernel? The first verions of the 2.6 kernels stable came out in early 2004. Once again, this series marks an important step in the integration of network functions [Kernel Traffic]. It includes all the major technical developments of the Internet
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The functions related to remote access via the PPP (Point to Point Protocol) have been completed to provide more opportunities for filtering and aggregation channels.
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The IPSEC protocols, IPv6 and IPVS are completely integrated into the kernels 2.6.xx.
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The traffic control, priorities and qualities of services are documented in the guide Linux Advanced Traffic Control HOWTO. All these functions are modular, they are associated with the needs expressed by politicians routing.
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The virtual networks (VLANs) and bridges network functions are increasingly used in high availability, redundancy and security.
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The access control by filtering allows the application of rules on fields layers liaison network, transport and application. The most recent work focused on filtering frame and on marking the flow of applications. The translation addresses source (SNAT) and destination (DTA) is an integral part of the functions of filtering netfilter / iptables.
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The tunnels over IP, including GRE, are also part of the core functions of Linux. Examples of configurations are available in Chapter 5 of Linux Advanced Traffic Control HOWTO. This type of function has evolved into virtual private networks (VPNs), found in the form of application and not in the kernel functions.
It is often difficult to understand the association of different functions in a core network such as Linux. Under what conditions is used to control traffic or access?. The answer is given with the transit diagram of a packet in the nucleus.