Internet Protocol Security IPsec is actually a suite pf protocols. Each protocol within the suite provides different functionality. Collective IPsec does everything except.

IPsec's ESP (Encapsulating Security Payload) protects packet payloads, and AH (Authentication Header) covers IP header fields, making header and payload protection core IPsec capabilities.

IPsec's ESP protocol natively supports symmetric encryption algorithms including AES and 3DES, making encryption a direct, built-in IPsec function.

IPsec operates at OSI Layer 3 (Network Layer) processing IP packets - it does not operate at Layer 2 (Data Link Layer), which handles frames, so this is already something IPsec does not do.

IPsec does not directly authenticate users or sessions - while AH provides packet-level data origin integrity verification, actual endpoint and user authentication is delegated to IKE (Internet Key Exchange) and external credential mechanisms such as certificates or pre-shared keys, so authentication is not an inherent IPsec built-in function.