The document summarizes Dan Kaminsky's talk at Black Hat 2007 about exploiting the DNS rebinding vulnerability to bypass firewalls and access internal networks from external web browsers. It describes how DNS rebinding works by abusing the same-origin policy to treat websites with different domain names but the same IP address as coming from the same origin. It then outlines several ways an attacker can force a domain to resolve to different IP addresses and use this to tunnel network traffic over the browser.