Complete Protocol dictionary, glossary and reference

AH: Authentication Header

Authentication Header, a protocol in the IPsec (Internet Security) suite, is used to provide connectionless integrity and data origin authentication for IP datagrams, and to provide protection against replays. This protection service against replay is an optional service to be selected by the receiver when a Security Association is established. AH provides authentication for as much of the IP header as possible, as well as for upper level protocol data. However, some IP header fields may change in transit and the value of these fields, when the packet arrives at the receiver, may not be predictable by the sender. The values of such fields cannot be protected by AH. Thus the protection provided to the IP header by AH is only partial in some cases.

Standard Organization

IETF

Related Document

RFC 2402