I think Catoosa is correct. They really don't care if you have a reuter. But, they refuse to give tech support for one. So, if something happens, some of the tech people will refuse to help you. Some don't care and will help you anyways.
Comcast's language isn't bizarre. They're saying that you are NOT allowed to share your connection outside of your domicile - i.e., you cannot be an end point on a non-Comcast LAN (which is what you would be if you were allowing your neighbors access via WiFi). They don't care how many of your own machines you connect to the WAN via a NAT router. As far as File and Printer sharing goes - their references to it in their text are for people who might connect a PC naked (without router) to the WAN but have file and printer sharing enabled with other computers on a home LAN - which could be exploited from the outside. I have multiple machines connected via a router and they all have file and printer sharing enabled - but since the router is firewalling the inside LAN, there is no exposure.
IP sharing cannot be audited: Pay for one IP and the router with built in DHCP and NAT allows multiple users to share the IP. Unless you are using very large bandwidth - traders workstations dont - then you dont need additional IPs.
Actually IP sharing CAN be audited with monitors doing packet inspection and looking at the NAT header that's carried in the packets. However, the real key point is that Comcast does NOT care how many machines you're using at your own house that are sharing the single WAN connection. Consequently, they have no interest in bothering to try to audit the traffic.
What I should have said was that no sane organization would attempt this level of processing: the costs would far, far, exceed the cost of providing the service. In practice, IP sharing can not be audited. In fact, if this was attempted it could be easily stopped by changing the algorithm in hardware - some products already do this .
I run 4 computers through a router that the Comcast tech support guy helped me set up over the phone (although they don't officially support it), never any problems. If you need multiple static IP addresses for some reason (If you don't know the reason, you don't need them....), then it will cost you the extra $5. Jessie
I have multiple computers behind router using comcast...never been a problem. When I call for support from Comcast, they usually ask me if I have a router or firewall, I tell them yes, no big deal.
The reason why they ask if your behind a firewall/router is because if they can't seem to troubleshoot the problem, they will blame your router. Had that happen to several of my friends. lol
I don't know about Comcast, but SBC (Pacbell) DSL charges for the number of computers on the line, regardless of whether you're using a single IP address with a NAT router or multiple IP addresses with one per computer. Here's the trick: DON'T TELL SBC THAT YOU'RE USING A ROUTER TO ATTACH MORE THAN ONE PC TO A SINGLE IP ADDRESS. If you do, they charge you more. SBC likes to overcharge anyway. Many of my customers (I do computer consulting) were originally set up with entire subnets (usually six usable static IP addresses, one gateway, one broadcast) when they naively told SBC they had two or three computers. SBC didn't care that they only needed two IP addresses; Their DSL bills were $200 to $300 per month, more than running two separate $50/month single DSL lines into their office! I told them to call SBC back and downgrade to a single DCHP'd IP address. Then, I set up a Linksys wireless firewall router, NAT the private network, and tell the client to never tell SBC they have more than one PC on the line. Saved 'em bundles!