A suite of protocols that provides secure communication over IP networks by encrypting and authenticating data packets. Operating at the network layer, IPsec can protect all IP-based traffic between participating devices, regardless of the applications generating that traffic.
How IPsec Works
IPsec operates at the network layer and supports two primary modes: Transport mode, which encrypts only the payload of IP packets, and Tunnel mode, which encrypts the entire packet for secure communication between networks or endpoints. It uses protocols like Authentication Header (AH) for integrity and Encapsulating Security Payload (ESP) for encryption.
Security Features
IPsec can authenticate peers using pre-shared keys or digital certificates. The Internet Key Exchange (IKE) protocol sets up a security association (SA) in the IPsec protocol suite. IKE builds upon the Oakley protocol and ISAKMP, using X.509 certificates for authentication and a Diffie-Hellman key exchange to set up a shared session secret from which cryptographic keys are derived.
Common Use Cases
Everyday use cases include Virtual Private Networks (VPNs), site-to-site encrypted links between data centers, and secure remote access for employees. IPsec is widely supported by operating systems, routers, and firewalls, making it a foundational technology for network security.