Forgive the top posting, but Lookout is the corporate standard.
It prevents you from typing at the bottom? How quaint :-)
Now, on to the topic at hand. Why would you scan the address space in the first place?
Maybe because you haven't really thought about the magnitude of the task? Maybe you feel that there's some likelihood of certain addresses being used? We've seen stupid things under IPv4, and it seems certain that IPv6 won't be immune to stupid vendor tricks.
Wouldn't it be easier to compromise a known host and look at the ARP table?
Maybe; however, it's not clear that this would be useful in generating a complete list of available hosts, though it would certainly provide the opportunity for finding more of them.
Or better yet, the router on the edge? If it's moving packets, something on the network has mapped the MAC address to its IP at some point.
And if it isn't moving packets, then maybe nothing has. The devices on a network that are just idling and may be forgotten or unloved may be at a fairly high risk for exploits and all that. Eventually this sort of thing is going to be a problem, as the number of network- attached devices is exploding. What's going to be more interesting is the number of devices that are (re-)programmable; we'll eventually see malware networks that are able to target more than just your CPE/router device, and will have attack vectors against your ATA, your TV, your DVR, your fridge, etc. The trick is to find those devices, but even in a bad case scenario, where you might have to scan the network to find additional devices to infect, the use of scanning alone isn't practical, but scanning for devices from a given manufacturer's MAC assignment pool might be, especially if you've essentially got forever in which to do it, and certainly sitting there passively on the network snooping is very practical. The fact that many people walk around with a cell phone that has a high speed processor and lots of memory in it says a lot about where consumer electronics is going, and that we're likely to be seeing a lot more of this sort of low-level bad guy activity that is able to target a list of heterogeneous targets. ... JG -- Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net "We call it the 'one bite at the apple' rule. Give me one chance [and] then I won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN) With 24 million small businesses in the US alone, that's way too many apples.