IPSec

Protocol Suite Overview

IPsec (Internet Protocol Security) is a suite of protocols that authenticates and encrypts IP packets at the network layer. Unlike application-layer encryption such as SSL/TLSSecure Sockets Layer / Transport Layer Security. Cryptographic protocols that provide encrypted, authenticated communication over a network. SSL is deprecated; modern implementations use TLS 1.2 or TLS 1.3., IPsec secures all traffic between two endpoints regardless of which application generates it. It operates in two modes: Transport mode encrypts only the payload of each packet, while Tunnel mode encapsulates the entire original packet inside a new encrypted packet — the basis for most VPNVirtual Private Network. A technology that creates an encrypted tunnel between a device and a remote server, protecting data in transit and masking the user's real IP address. Used for privacy, security, and accessing restricted networks. implementations.

Key Protocols Within IPsec

IPsec relies on two sub-protocols. Authentication Header (AH) provides data integrity and authentication but no encryption. Encapsulating Security Payload (ESP) provides both encryption and authentication and is used in virtually all modern deployments. Internet Key Exchange (IKE), currently at version 2, handles the negotiation of EncryptionThe process of converting plaintext data into ciphertext using a cryptographic algorithm and key, making it unreadable without the corresponding decryption key. The foundation of secure communication on the internet. algorithms and the exchange of cryptographic keys between peers.

Practical Deployment

IPsec is widely used in site-to-site VPN connections between corporate offices and in remote-access VPNs, often paired with L2TPLayer 2 Tunneling Protocol. A VPN tunneling protocol that encapsulates data but provides no encryption on its own. Almost always paired with IPSec (L2TP/IPSec) to add confidentiality and integrity. to add tunneling capabilities (L2TP/IPsec). It is also the underlying protocol for many router-level VPN TunnelAn encrypted, encapsulated connection between two endpoints through which all tunneled data passes securely across an untrusted network like the public internet. configurations. Because it operates below the application layer, it is transparent to software and requires no client-side application changes beyond the VPN client itself.