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Home / Glossary / ESP
Glossary · Protocol

ESP

Encapsulated Security Payload

In plain language

The part of a secure VPN tunnel that scrambles the data and checks it was not changed on the way.

The metaphor

Like a tamper-evident armoured wrapper around every parcel travelling through the tunnel.

Going deeper

How it works

  • It is one of the two main parts of IPsec.
  • It hides the contents and proves the data has not been altered.
  • It runs after the two ends have agreed on keys.
  • Firewalls need to allow it for office-to-office VPNs to work.

How WILDCARD handles it

Network covers the managed firewall and switches that sit behind your provider's modem.

In practice
  • A branch office connects to head office through an IPsec tunnel.
  • A firewall log shows this traffic passing between two sites.
  • A VPN fails because a router in the middle blocks it.

A question owners ask

Do I need to know this?

No. It matters only when a site-to-site VPN breaks and someone needs to check what the firewall allows.

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

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