|IPSec - IP Security protocol suite|
2406 -ESP (Encapasulating Sec. Payload)
2402 - AH (Authentication Header)
IPSec is a suite of protocol consisting of pricipally two: Authentication Header protocol (AH) and Encapsulation Security Payload (ESP) protocol. Its purpose is to provide security services to IP, which inherently lacks them. The primary services are data integrity, data origin authentication, and data confidentiality.