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ccna book barnes and noble.IPSec is an IETF standard (RFC2401-2412) that defines how to configure a VPN using the IP addressing protocol. IPSec provides data confidentiality, data integrity, and authentication of the origin of the data. IPSec does not bind any specific encryption, authentication, security algorithms, or key technologies. IPSec is a framework of open standards that spells out the rules for secure communication. IPSec relies on existing algorithms for encryption, authentication, and key exchange.IPSec I works at the network layer to protect and authenticate IP packets between the IPSec devices (peers) involved in the communication. Because protection can be implemented from layer 4 to layer 7, IPSec is capable of protecting traffic for almost any application. The various implementations of IPSec use an explicit Layer 3 header, so there are no routing issues. IPSec works on all Layer 2 protocols, such as Ethernet, ATM^ Frame Relay, SynchronousData Link Control (SDLC), and High-LevelData Link Control (HDLC).The IPSec framework consists of five components.8.3 IPSec VPN Components and Operations 227The first component represents the IPSec protocol. Either the Authentication Header (AH) protocol or the Encapsulating Security Payload (ESP) protocol can be selected.The second component represents the type of confidentiality achieved using an encryption algorithm, such as DES, 3DES, AES, or SEAL. This selection depends on theThe required level of security. The third component represents integrity, which can be implemented using MD5 or SHA.The fourth component represents how to establish a shared key, and there are two ways to do this: pre-shared or digitally signed using RSA. The last component represents the DH algorithm group. There are four DH key exchange algorithms to choose from, including DHGro 1 (DH1), DHGroup 2 (DH2), DHGroup 5 (DH5), and DH Group 7 (DH7). Which type of group is selected depends on the specific requirements. IPSec provides the framework and the administrator selects the algorithms used to implement security services within that framework. Because IPSec is not bound to a specific algorithm, newer and better algorithms can be implemented without patching existing IPSec standards.IPSec can protect a path between a pair of gateways, a pair of hosts, or a gateway and a host. IPSec provides the following basic security features through the IPSec framework.