GRE Tunnel

GRE encapsulates packets to create tunnels across IP networks.

Updated: 2026-03-05

Definition

Generic Routing Encapsulation (GRE) wraps packets inside another IP packet to create a tunnel.

GRE provides encapsulation but not encryption by itself.

Key points

Encapsulation (tunneling)
No encryption by default
Often combined with IPsec for security

Common mistakes

Assuming GRE is secure without IPsec/TLS.
Not accounting for MTU overhead and fragmentation.

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Related terms

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