IPsec is a security protocol for the Internet Protocol layer that you can use, for example, to set up a secure tunnel between machines or networks.

It consists of these subprotocols:

AH (Authentication Header)
Guarantees the integrity of the IP packet and protects it from intermediate alteration or impersonation, by attaching a cryptographic checksum computed by one-way hash functions.
ESP (Encapsulated Security Payload)
Protects the IP payload from wire-tapping, by encrypting it using secret-key cryptography algorithms.

IPsec has these modes of operation:

Protects peer-to-peer communication between end nodes.
Supports IP-in-IP encapsulation operation and is designed for security gateways, such as VPN configurations.
Note: The IPsec support is subject to change as the IPsec protocols develop.

For more information, see IPSec in the QNX Neutrino C Library Reference.