Microsoft has released an update package to enhance the current functionality of the Layer Two Tunneling Protocol (L2TP) and Internet Protocol security (IPSec) on computers that are running Windows XP or Windows 2000. This update includes improvements to IPSec to better support virtual private network (VPN) clients behind network address translation (NAT) devices by implementing NAT as specified in the Internet Engineering Task Force (IETF) RFC 3193 and draft-02 of the IETF NAT-T specification. The update also includes additional support for stronger IPSec protection by using the 2048-bit Diffie-Hellman algorithm (Group 14). Knowledge Base Article Download via WindowsUpdata