Neglected IPv6 features endanger the LAN

Protocol Duties

Article from ADMIN 10/2012

By Egon Grünter , By Werner Anrath , By and Sabine Werner

IPv6 is establishing itself in everyday IT life, and all modern operating systems from Windows, through Mac OS X, to Linux have it on board; but if you let IPv6 introduce itself into your environment, you could be in for some unpleasant surprises.

In 1995, the Internet Engineering Task Force (IETF) chose IPv6 as the successor to IPv4. Initially, this was not an issue that raised much interest. But this changed when Microsoft added IPv6 support to its Windows Vista and Windows Server platforms in 2007. Linux in all its variants and Apple's Mac OS X followed suit; thus, the new protocol spread with each new installation. On all of these computers today, IPv6 is active by default, communicating in unsolicited dual-stack operations using IPv4 and IPv6. Moreover, Microsoft's operating systems introduced transition technologies, which use IPv4 as a link-layer protocol for IPv6 use. This happens autonomously and, in some cases, long before admins organize normal IPv6 operations – which is exactly where the latent threat lies.

Dual-Stack on the LAN

The most common operating systems on the LAN are Windows, Linux, and Mac OS X. They all run IPv6 in parallel with IPv4. IPv6 is enabled and active by default, and the systems on the network communicate via dual-stack operations (Figure 1). The overview in Table 1 shows the default settings for current operating system versions.