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Home / Glossary / AH
Glossary · Protocol

AH

Authentication Header

In plain language

A part of the IPsec system that proves each packet came from the sender and was not changed, without hiding its contents.

The metaphor

Like a tamper-evident seal on a clear package: you can see inside, and any change shows.

Going deeper

How it works

  • Signs each packet.
  • Does not encrypt the contents.
  • ESP is more common because it does both.
  • Does not work through address translation.

How WILDCARD handles it

Network covers the firewall that sets up secure links between sites.

In practice
  • An older link uses it for integrity checks.
  • A VPN settings page lists it beside ESP.
  • A device refuses to connect through a router doing address translation.

A question owners ask

Do I need to choose it?

Rarely. Modern setups use the version that also encrypts.

Where WILDCARD handles this
Network
  • Firewall managed and monitored
  • Switches kept current
  • On-prem Active Directory auth
Start with Network
Related terms
ACLAccess Control ListAPAccess PointARPAddress Resolution ProtocolBPDUBridge Protocol Data UnitCCMPCounter Mode/CBC-MAC ProtocolCCTVClosed-circuit TelevisionCHAPChallenge Handshake Authentication ProtocolCSUChannel Service Unit

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