IKE

The protocol that negotiates security associations and keys for IPSec.

Internet Key Exchange negotiates and manages the security associations and shared keys that an IPsec VPN uses to encrypt and authenticate traffic. It typically runs in two phases: the first establishes a secure, authenticated channel, and the second derives the keys protecting actual data, often using Diffie-Hellman for forward secrecy. It matters as the control plane behind IPsec tunnels. A pitfall is weak configuration such as aggressive mode with preshared keys, which can expose authentication material to offline cracking.