Comcast Outlawing use of NAT

zxc47 · Post by **zxc47** » Tue Aug 27, 2002 1:22 am

Comcast Outlawing use of NAT.

According to an article in Slashdot, COMCAST is starting to search for users that share a single IP address among several computers using a technique called 'Network Address Translation' (NAT).
This technique is employed by basically all internet gateways (Linksys, Windows Internet Connection Sharing, Linux Firewalls), that allow you to connect multiple computers to the internet using a single IP address.
So far, some cable companies outright allow the use of NAT at not additional charge (with the caveat that problems routed in such setups are not covered by tech support). Even if it is not outright allowed, cable companies so far just didn't care. You only have to pay extra in most cases if you are asking for multiple IP addresses.
Lately, several cable ISPs however started to offer their own NAT / home networking solutions. Some of which compete with the cheaper do it yourself methods.
The current Comcast subscriber agreement (as posted on Comcast's web site on 1/25/2002), does only exclude reselling. So according to this, you are not allowed to share the cable modem with your neighbors and charge them for it.

MtCableman · Post by **MtCableman** » Tue Aug 27, 2002 9:31 am

Old news.

Question:
How would they be able to tell that you are using a router? Would the sniff every packet of information? Wouldn't the Router's natural firewall keep them from seeing the computers on the other side of the NAT? Wouldn't they run out of IPs to give to the customers? Seems like a lot of work to see if you are using a router or not.

Indy · Post by **Indy** » Tue Aug 27, 2002 9:50 am

Originally posted by MtCableman
Old news.

Question:
How would they be able to tell that you are using a router? Would the sniff every packet of information? Wouldn't the Router's natural firewall keep them from seeing the computers on the other side of the NAT? Wouldn't they run out of IPs to give to the customers? Seems like a lot of work to see if you are using a router or not.

They can tell what is hooked up to the modem by the mac address that is reported back to the headend. So, if you have a 3com card in your computer, they can see that fact from the main office. Same with a router. However, most routers can spoof a mac address, so you can make your router look like a regular nic card with the right mac address in it...

zxc47 · Post by **zxc47** » Tue Aug 27, 2002 10:09 am

MtCableman: I just ran across that on the net and though it was funny.With cable and DSL lock in a war for new user you would think that they would not even be think about stupid stuff like that.With my cable co. I ask if I could run two modem, one for each computer they said no.One modem per household.They told me to get a router or switch and set up a network.

MtCableman · Post by **MtCableman** » Tue Aug 27, 2002 7:44 pm

Originally posted by Indy

They can tell what is hooked up to the modem by the mac address that is reported back to the headend. So, if you have a 3com card in your computer, they can see that fact from the main office. Same with a router. However, most routers can spoof a mac address, so you can make your router look like a regular nic card with the right mac address in it...

That is true but I pretty sure you could only tell the manufacturer by MAC. Most manufacturers make routers as well as NICs so you couldn't really tell if the MAC is a router or a NIC by that manufacturer. Besides you answered the question by stating the"cloning" of a MAC by the router. My D-Link 704P can do that so on the internet side it would look like my NIC.

The Dude · Post by **The Dude** » Wed Aug 28, 2002 8:40 pm

Here is a clause from the "Terms of use policy" for my ISP

(f) While you are welcome to run gaming servers, you are not allowed to run FTP, Web, IRC or other servers. You cannot run proxy servers such as WinGate or WinProxy, or utilize any other method to connect multiple machines to a single cable modem. The residential service price is based on one machine utilizing the network. Operating any type of server, other than a gaming server, will result in the deactivation of your cable modem.

I was using Windows ICS to connect two PC's. They found out somehow and had my account flagged. They wouldn't give me any tech support. I switched to a router and had to call them because they use the mac address. I could have cloned the Mac address but at the time I didn't know it. I told them I wanted it for the firewall protection. I even asked them if I would have to pay extra if I connected another PC. They said no since I would not need another IP, the router would do it for me. Good enough for me. The way I see it, it's better for them. I'm not stealing any bandwidth since it's split between all the PC's on the router. Also it gives them more IP addresses to hand out, since I only require one. They get enough from me anyway since I get my digital TV from them too. Probably why they didn't disconnect me in the first place.

therealcableguy · Post by **therealcableguy** » Fri Aug 30, 2002 5:28 am

Originally posted by zxc47
I ask if I could run two modem, one for each computer they said no.One modem per household.They told me to get a router or switch and set up a network.

Thats interesting.We will allow you to have more than one modem in your house,however, you will pay full price(39.95) for each one.We have a few customers with that setup.I would never recommend it.I explain the options of a cable/dsl router,but,we have had them pay anyway.

YARDofSTUF · Post by **YARDofSTUF** » Mon Sep 02, 2002 7:36 am

Originally posted by Indy
They can tell what is hooked up to the modem by the mac address that is reported back to the headend. So, if you have a 3com card in your computer, they can see that fact from the main office. Same with a router. However, most routers can spoof a mac address, so you can make your router look like a regular nic card with the right mac address in it...

i think my router can do that. hope so, i may need it

Robot Army · Post by **Robot Army** » Mon Sep 02, 2002 10:02 am

Found this in another forum. Hope it helps to allay any fears you may have....

http://www.bitzenbytes.com/101/101.htm

go to Network, then Comcast 101