An IPSec protocol that provides confidentiality, in addition to authentication, integrity, and anti-replay. ESP can be used alone, in combination with AH, or nested with the Layer Two Tunneling Protocol (L2TP). ESP does not normally sign the entire packet unless it is being tunneled-ordinarily, just the data payload is protected, not the IP header.
A fundamental component of IPSec-compliant VPNs. Specifies both encryption of an IP packet, as well as data integrity checks and sender authentication, which are added as a header to the IP packet.