Encapsulation security payload

Protocol, which is designed to provide a mix of security services in IPv4 and IPv6. ESP can be used to provide confidentiality, data origin authentication, connectionless integrity, an anti-replay service (a form of partial sequence integrity), and (limited) traffic flow confidentiality. (RFC 4303) Scope Note: The ESP header is inserted after the IP header and before the next layer protocol header (transport mode) or before an encapsulated IP header (tunnel mode).