In the old days of DOCSIS, I was able, during failures of DHCP (for various reasons) to self assign a "nearby" IP address in the same subnet and this worked fine as long as that IP wasn't being used by someone else at the time. While this was done to cope with some failures or bad policy at the cable company with no ill intent, I realise that I could have used this technique to do bad stuff on the internet with DHCP logs pointing to some neighbour (or poiting to nothing). Has this "loophole" been plugged with the advent of DOCSIS2 and now DOCSYS3 software ? Or is DHCP still just a "suggestion" of what IP to use, with ARP being the authoritative mechanism used by the CMTS to know the MAC address associated with an IP address ? If this has been solved, at what level was it done ? is it the DOCSYS modem that sets up a filter based on a DHCP response to only let traffic "from" the assigned IP address through ? Or would it be done at the CMTS (again based on the DHCP response being recorded) ? I ask this in the context of the law where one party tries to sue another based on IP address (such as Voltage Pictures suing thousands of IP addresses). If B can use the IP address that DHCP assigned to A and A gets sued, it becomes rather difficult to prove.