Endnote 99 STP attacks are themselves relatively new, having been initially proposed in Phrack GG magazine in 2002, and investigated at Black Hat Europe HH in 2005 with the introduction of Yersinia. Because of this it is likely that intruders have not yet begun to take full advantage of STP-based attacks. We can expect this sort of attack to become more prevalent. SuMMARy Because layer two in general, and the STP in particular, have no inherent security, layer 2 attacks will continue and pose a serious risk to network security. Other pro- tocols exist at layer two and these can also be exploited; many of these exploits are already implemented in Yersinia. Since layer two creates the foundation for your entire network, any trouble on this level can be difficult to diagnose and can mani- fest itself in several ways. The incident detailed at the start of this chapter illustrates the trouble that can arise, or that an intruder can cause, using a layer 2 protocol such as STP. This chapter explained what layer two is and investigated STP in particular. You