IpSec is a suite of protocols aimed to provide SecurityManagement technology for IP packets transported over the internet. It is developed by InternetEngineeringTaskForce (IETF) and is widely in use for VirtualPrivateNetwork (VPN).
From Cisco documentation, IpSec include a list of optional security services:
- Data confidentiality
- Data integrity
- Data origin authentication
- Antireplay
Resources
- IP Security protocol based VPNs' http://www.sans.org/rr/papers/44/372.pdf
- Remote Access IPSec VPNs http://www.sans.org/rr/papers/20/877.pdf