Definition: IPsec (Internet Protocol Security) provides security services at the IP layer by enabling a system to select required security protocols, determine the algorithm(s) to use for the service(s), and put in place any cryptographic keys required to provide the requested services. The IPsec architecture is described in the RFC-2401 (www.ietf.org RFC-2401). IPsec has been selected to be embedded in IPv6. IPsec is strong because it was designed that way in order to replace older methods like PPTP.
IPsec is recognized as the most secure way to access the corporate network from the Internet, and here's why:
Strong encryption mechanisms like Encapsulated Security Payload (ESP) using AES with long key length (i.e. 256, 512)Strong user authentication using Certificates with long key lengths (i.e larger than 2048 bytes)Use of Internet Key Exchange (IKE) and ISAKMP to automatically exchange keys for mutual authentication.Protection against denial of service attacks: the IPsec protocol uses a sliding window. IP packets are numbered and accepted only if they fit into the window.Support for smart cards and USB tokens, enabling multifactor authentication (MFA).