Abstract A broad analysis was performed on the network-facing components of the Microsoft Windows Vista TM release version. Our analysis explores how it affects network security and how it differs from previous versions of Microsoft Windows. Windows Vistafeatures a rewritten network stack, which introduces a number of core behavior changes. Windows Vista also introduces a numberof new protocols, most importantly IPv6, its supporting protocols, and several IPv4 to IPv6 transition protocols. As a clientoperating system, Windows Vista will be widely deployed and as such is an important topic for security research. We studied thefollowing protocols and technologies: LLTD, IPv4, IPv6, Teredo, TCP, SMB2 named pipes, MS-RPC, and the Windows Firewall.We also studied ARP, NDP, IGMP, MLD, ICMPv6, and UDP.