Internet Protocol security (IPSec) in the Microsoft Windows Server 2003 operating system helps protect networks from active and passive attacks by securing IP packets through the use of packet filtering, cryptographic security services, and the enforcement of trusted communications. IPSec is integrated within the security framework of Windows Server 2003, which allows you to use Active Directory domains to provide identity and manage trust relationships between users and computers in different departments within an organization.
This subject provides a high-level description of IPSec that includes the scenarios for which it is intended and not intended.