Layer 2 Tunneling Protocol (L2TP)

Security+ 🏆 • Protocols 🔗 • Network Security 🌐 • Difficulty: premium

Definition

L2TP is a tunneling protocol that carries Layer 2 sessions, commonly PPP, across IP networks. L2TP does not provide encryption by itself, so it is typically paired with IPsec to create a secure VPN.

Examples

  • A remote access VPN uses L2TP with IPsec so a user can connect securely to the corporate network over the internet.
  • An organization uses L2TP/IPsec for compatibility with built-in VPN clients on older operating systems.

Discover 🔎

Tunneling is a networking trick that lets you carry traffic through places it normally should not travel, like transporting a private network session across the public internet. L2TP is often mentioned in VPN discussions because it creates the tunnel that carries the session. The important security takeaway is simple. L2TP builds the tunnel, but it does not lock it. That is why L2TP is almost always paired with IPsec when security is required.

Remember: L2TP is the tunnel mechanism. IPsec is commonly used to add encryption and authentication.
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