Internet Exchange Points (IXPs) exist all over the world for the purpose of, as the name suggests, exchanging internet dataz between networks. They're a pretty good way of keeping local traffic off transit links which has all sorts of benefits for network operators consumers of internets alike. For relatively low cost, IXPs can also get an attacker layer 2 adjacent to a significant number of ISP routers for fun and profit. Sometimes those routers do things that their operators might not expect, and sometimes they do things that their operators probably don't want them to be doing. Some of the reasons why connecting a Serious ISP Network to an IXP should be approached with a little more caution than it currently appears to be will be covered, along with some examples of what happens when appropriate precautions are not taken.