IPsec is best thought of as a set of features that protects IP data as it travels from one location to another. The locations involved in the VPN typically define the type of VPN. A location could be an end client (such as a PC), a small remote office, a large branch office, a corporate headquarters, a data center, or even a service provider. The combination of any two of these locations determines the type of VPN in use. For example, a small remote office connecting to a corporate headquarters would be a site-to-site VPN.

IPsec consists of the following features:

1- Data confidentiality
2- Data integrity
3- Data origin authentication
4- Anti-replay

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