IPSec is a framework or suite of protocols combined to ensure secure data communication across an IP network. IPSec combines different protocols to provide data confidentiality (encryption), data integrity (hashing), authentication (PSK and RSA digital certificates), and key exchange (Diffie-Hellman) between devices over an untrusted network:
Within the IPSec framework, there are two protocols that assist with the transportation of IP packets across the IPSec VPN tunnel, these are known as Authentication Header (AH) and Encapsulation Security Payloads (ESPs).
When creating an IPSec VPN tunnel, either the AH or the ESP can be used as a standalone protocol. However, both AH and ESP can be used together.
