&gt; Yes, but by default a modem from your ISP is acting as a NAT device routing to a private IP space.<p>Not in my experience. The default modem provided by both Comcast and Knology (who is -I guess- now WOW!) is (or was, in the case of Knology) a bridge device that requires you to provide your own router. You have to ask for a modem that&#x27;s also a router to get something that&#x27;s not a bridge.<p>That doesn&#x27;t mean that the modem doesn&#x27;t have an IP address, mind. AIUI, on Comcast&#x27;s network the <i>modem</i> gets an IPv6 address so that they can do network management stuff to it.