SlashDot: "Comcast Gunning for NAT Users"

Daniel Golding dgolding at
Thu Jan 31 17:15:06 UTC 2002

Hmm. I doubt Comcast is actually doing this - they are far too busy actually
trying to build a network, out of the ashes of the @home debacle. However,
even if they were, there isn't really anything wrong with it. We scratch our
heads, collectively, when a large broadband provider goes chapter 11, but
then oppose a pricing model that might be profitable. Now, if a provider was
refusing to provide extra IPs, then I could see the problem. However, if a
provider is willing to provide extra IPs for something reasonable like
$5/month, more power to them. There are several good reasons why they might
want to ban NAT:

1 - When you come to the stadium, you can't bring in your own hot-dogs. It's
the same sort of thing - the hot dogs are subsidizing the ticket price. In
this case, extra fees for things like IP addresses and extra email boxes,
are the concession items.

2 - Support issues - supporting a largely clue-challenged user base, is hard
enough without people slapping linksys routers in, then expecting the ISP
to, defacto, provide support. Anyone remember when the only supported router
for UUNet ISDN lines was the Pipeline 50? This was to (in theory) enable

3 - NAT is wonderful, but we aren't running out of IP addresses that
quickly, and NAT will break some applications. Large scale NAT is probably
not the solution to future IP address exhaustion problems. Providers who do
this are not being bad guys, because extra IP addresses cost less than the
costs of supporting NAT boxes. If folks don't like this, they can become
involved with ARIN and propose some bizarre price-support scheme for IP
addresses, to encourage NAT, I suppose.

4 - This is, of course, an unenforceable policy (which is why I suspect it
does not exist). However, it is very reasonable for a provider to refuse to
support a customer with a NAT box, if the customer is buying a single user

One usage policy I would support: never again seeing the word "slashdot" in
the subject line of a NANOG email :)

- Daniel Golding

> -----Original Message-----
> From: owner-nanog at [mailto:owner-nanog at]On Behalf Of
> Martin J. Levy
> Sent: Thursday, January 31, 2002 10:58 AM
> To: nanog at
> Subject: Fwd: SlashDot: "Comcast Gunning for NAT Users"
> I got this forwarded to me.  I'm not impressed.
> Based upon the general desire for providers to have NAT'ed users
> and to reduce IP-space usage where appropriate, does this make
> sense?  I can understand the providers desire to increase
> revenue, but I don't believe this is a good way to do it.
> Besides the technical difficulties of detecting a household that
> is running a NAT'ed router, why not win over the customer with a
> low-cost extra IP address vs: the customers one-time hardware
> cost for the router.  There are people who would be willing to
> pay some amount monthly vs: (let's say) $100 for a NAT box.
> Does anyone know what percentage of home broadband users run NAT?
>  Does anyone have stats for IP-addresses saved by using NAT?
> Martin
> ------ Forwarded Message
> From: Ward Clark <ward at>
> Date: Sat, 26 Jan 2002 15:00:32 -0500
> To: "NetTalk" <nettalk at>
> Subject: SlashDot: "Comcast Gunning for NAT Users"
> Today's MacInTouch links to a report that appeared in SlashDot on
> Thursday:
> "A co-worker of mine resigned today. His new job at Comcast: Hunting down
> 'abusers' of the service. More specifically, anyone using NAT to connect
> more than one computer to their cable modem to get Internet access-
> whether or not you're running servers or violating any other Acceptable
> Use Policies. Comcast has an entire department dedicated to eradicating
> NAT users from their network. ... did anyone think they'd already be
> harassing people that are using nothing more than the bandwidth for which
> they are paying? ..." Earthlink and Comcast have both been advertising
> lately their single-household, multi-computer services (and additional
> fees) -- probably amusing to many thousands of broadband-router owners,
> at least until the cable companies really crack down.
> There's a huge number of responses (691 at the moment), which I quickly
> scanned out of curiosity.  I'm not a Comcast or Earthlink user.
> You can start here:
> -- ward
> --------------------
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> ------ End of Forwarded Message

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