IPsec Modes: Transport and Tunnel

You just saw that three different basic implementation architectures could be used to provide IPsec facilities to TCP/IP networks. The choice of which implementation you use, as well as whether you implement in end hosts or routers, impacts the specific way that IPsec functions. Two specific modes of operation that are related to these architectures are defined for IPsec. They are called transport mode and tunnel mode.

IPsec modes are closely related to the function of the two core protocols, AH and ESP. Both of these protocols provide protection by adding a header (and possibly other fields) containing security information to a datagram. The choice of mode does not affect the method by which each generates its ...

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