Mailing List Archive

Comcast Customer Owned Modem Firmware : WAS : Xfi Advances Security (comcast)
Jason-

I have a sidebar question here.

I came across the AQM paper you and others recently published. (
https://arxiv.org/pdf/2107.13968.pdf ) In that paper, the following is
stated :

When a customer purchases their own cable modem, they are responsible for
> administering it, updating the software, configuring it, replacing it if it
> fails, and so on. These modems are generally referred to as Consumer Owned
> And Managed (COAM) devices.



> An important distinction between leased and COAM modems is support for the
> operating firmware. For COAM devices, the modem’s operating firmware is
> provided by the modem’s manufacturer, who controls the feature set, bug
> fixes, and firmware release schedule (to the extent that there even are any
> post-sale software updates).


Does Comcast actually allow customers who own their own modems full
management of the modem firmware? As far as I have been aware since my time
at Adelphia 20-odd years ago, that has never been allowed by provider; all
users of a given model had the same firmware enforced, customer owned or
leased didn't matter.

On Mon, Sep 13, 2021 at 5:58 PM Livingood, Jason via NANOG <nanog@nanog.org>
wrote:
>
> On 9/13/21, 12:02, "Owen DeLong" <owen@delong.com> wrote:
> > Yes, but it’s tragically opt-out instead of opt-in as it should be.
>
> It is not a default for an Internet access service. It comes bundled as
one of several features in an optional add on service. See
https://www.xfinity.com/learn/internet-service/modems-and-routers for
details. This is targeted at the average consumer, particularly those that
may want parental controls, mesh WiFi, a voice port, and so on - so not
really targeted at NANOG list subs like us. ;-) That said, I have an XB7
modem at home and really like it a lot - especially the new AQM feature
that dramatically lowered working latency.
>
> > That means that anyone whose site happens to get miscategorized by them
gets the added costs of dealing with the user complaints instead of Comcast
having to bear the costs of their error.
>
> As my other reply noted, this service uses a bunch of 3rd party services
and it is those 3rd parties that maintain the lists (a la anti-spam and
anti-phishing email list vendors). So if an IP/FQDN/URL happens to be on
"our" list it is very likely getting filtered/blocked in a lot of network
places because it is on a well-known independent list.
>
> BUT, how do we know that was even the case here? Do we have a traceroute
or a screen shot of an error or block message? We seem to have concluded it
was blocked by a content filter but what technical evidence do we have
(that can help troubleshoot)? I know you are not the OP (it is Chris) - but
I'd love to know more technical detail and I am in communication off-list
with the OP (along with my colleague Tony Tauber, who was the first to
reach out to Chris 1:1).
>
> Jason
>
>
>
Re: Comcast Customer Owned Modem Firmware : WAS : Xfi Advances Security (comcast) [ In reply to ]
On 9/16/21 08:13, Tom Beecher wrote:

> Does Comcast actually allow customers who own their own modems full
> management of the modem firmware? As far as I have been aware since my
> time at Adelphia 20-odd years ago, that has never been allowed by
> provider; all users of a given model had the same firmware enforced,
> customer owned or leased didn't matter.

I can't speak for Comcast, but my local cable company indeed flashes
COAM modem firmware to whatever their latest approved version is at
least on installation and perhaps periodically thereafter. When I bought
my modem and it was first put online its firmware was upgraded
over-the-wire as one of the first steps of provisioning.

Even owned modems are TTBOMK very limited on what the customer can do
with them. SNMP typically isn't available on the ethernet side for
example. About all one can do is parse the HTML on 192.168.100.1 (in
most cases) to get an idea of signal quality, etc. If the modem has
built-in wi-fi you can expect the cable company to enable it for their
roaming customers to piggyback on your RF, resulting in interference
even if you turn off your own wi-fi in the modem.

Leasing a modem from the cable company seems to universally be a
terrible deal for the customer. DOCSIS 3.1 modems go for about $100 new
retail in quantities of one. I'm sure they're much less when a cable
company buys them by the tens of thousands in bulk packaging. At $10 to
$16 per month it makes zero sense for anyone to rent one. Of course the
phone companies did the same thing for decades with extension phones.

--
Jay Hennigan - jay@west.net
Network Engineering - CCIE #7880
503 897-8550 - WB6RDV
Re: Comcast Customer Owned Modem Firmware : WAS : Xfi Advances Security (comcast) [ In reply to ]
> Does Comcast actually allow customers who own their own modems full management of the modem firmware? As far as I have been aware since my time at Adelphia 20-odd years ago, that has never been allowed by provider; all users of a given model had the same firmware enforced, customer owned or leased didn't matter.

No and I am not aware of any DOCSIS network operator that does permit that. But we are very responsive to firmware updates from the OEMs and try to quickly test & deploy those. See for example: https://kb.netgear.com/000036375/What-s-the-latest-firmware-version-of-my-NETGEAR-cable-modem-or-modem-router

Thx
Jason