
Comcast turns 50,000 paying customer homes into public hotspots - jrochkind1
http://www.extremetech.com/computing/184263-comcast-turns-50000-paying-customer-homes-into-public-hotspots-millions-more-by-the-end-of-the-year
======
jamesbrownuhh
Frightening level of stupidity in that article ("Exact details of the setup
aren’t yet known" says the writer, so then go on to pull numerous
scaremongering scenarios out of a hat) and especially stupid stupidity in the
comments too.

Why is this so hard to understand? Router broadcasts a second SSID. Router
ensures that connections to that SSID are completely isolated from your own
network, never touch your IP address or internal devices, and are tunnelled
back to base over a separate channel VPN.

In scenarios where you are maxing out your net connection and someone else is
using the guest wifi too, your traffic always takes priority. That's a rule
right there - the kind of thing that routers are kind of good at.

It also means that you have access to free wifi when you're out and about, as
you can use your Comcast ID to use this same wireless in other locations.

As has been pointed out several times, many ISPs around the world do this.
It's simple and convenient and not remotely worthy of the scaremongering and
technical ignorance being displayed.

~~~
borplk
Does this open the door for people to capture their outgoing traffic which
will include the traffic of people who are using their router? If you use the
ComcastID and connect to someone else's router your non-encrypted traffic is
up for grabs?

~~~
eli
No it is a separate network

~~~
borplk
But the traffic is going out of your cables at some point no? Is it not
possible to capture that even if it's on a different network?

~~~
gizmo686
It is certainly possible, but it is far easier to just join the second network
and run a packet sniffer. You could also sniff in monitor mode to see traffic
on all networks in range, but driver support for that can be annoying.

------
abalone
This is quite common in Europe. In fact this sounds exactly how the BT FON
crowdsourced wifi network works:
[https://www.btfon.com](https://www.btfon.com)

The opening line of the article's totally wrong in saying this "would be
inconceivable if it was any other company than Comcast".

~~~
_pmf_
> This is quite common in Europe.

The fuck it is.

~~~
1gn1t10n
I know for a fact that at least two major ISPs in France already do this (SFR,
Free).

~~~
illumen
and in Spain, Germany, Portugal, Italy, and the United Kingdom. Which covers
quite a lot of Europe already, not even counting the rest of the places that
do this.

------
coenhyde
The public wifi and the private wifi have different public ip's but counter to
Comcast's claim that the second wifi does not effect the internet speed, it
does. I know this because I discovered the xfinitywifi network coming out of
my box about 2 months ago and did some tests.

I called Comcast to ask them to wtf was going on, they refused to disable is
saying it was a service to the public, bla bla bla. I was able to disable in
their admin panel though.

~~~
leorocky
You can just install your own router too. You can get a Motorola cable modem
that works just as fine as whatever they put in there I imagine. I have my own
modem.

The only time having my own modem has ever been an issue is when I called
customer service about network issues. They wanted to blame my modem, but
that's never been the actual problem (last time it was a bad cable outside the
house).

You could also shield that thing so it can't effectively broadcast wifi and
connect your own wifi router with a cable.

~~~
ohazi
This is not strictly true. I own my own cable modem (bought it on Amazon
before signing up with Comcast - [http://www.amazon.com/Motorola-SURFboard-
Gateway-SBG6580-Wir...](http://www.amazon.com/Motorola-SURFboard-Gateway-
SBG6580-Wireless/dp/B0040IUI46/)) and I specifically picked this one because
it was on Comcast's list of recommended modems and reviews suggested that it
worked without headaches on Comcast's network.

HOWEVER, after installing the device, I eventually started to notice that the
firmware was being updated remotely, without my intervention. At one point the
Motorola administrative web UI was replaced completely with a new Arris UI
(this was a few months ago when Comcast was experimenting with their IPv6
rollout). This lasted for about a month before the firmware was reverted back
to an older Motorola image (and now I no longer have IPv6 at home -- I guess
there were issues).

So yes, you can install your own router. But at least in some (most?)
instances, your cable provider may have direct access to the firmware on your
router, which essentially means that they can pull shit like this whenever
they want, without your knowledge or intervention.

TLDR: Comcast can update the firmware on _my_ cable modem without my knowledge
or intervention. Because it's an all-in-one device, that basically means they
can do whatever the fuck they want.

~~~
leorocky
Wow. How could Comcast control the firmware updates for a product they didn't
make? Did they hijack the update software lookup? This must have been done
with Motorola's backing.

~~~
ohazi
So I looked into this a while ago and wasn't really able to find an
authoritative answer. Farthest I got was here:
[http://forums.comcast.com/t5/Home-Networking-Router-
WiFi/DOC...](http://forums.comcast.com/t5/Home-Networking-Router-
WiFi/DOCSIS-3-0-Modems/td-p/778147)

The claim seems to be that Comcast has the ability to update the firmware of
any modem that is physically connected to their network. I don't know if this
is actually true. There might be some obscure part of the DOCSIS spec (or an
extension) that specifies how firmware updates can be delivered from the coax
side (if so, I've certainly never been able to find it, and I don't even want
to think about what they're (not) doing for security and authentication).

If this claim is true, then the best you can do is to get a dumb "modem only"
device, in order to minimize their control of your hardware and network. Use
your own router and/or your own wireless gateway and maintain exclusive
firmware control over those devices.

If the claim is false, then they're likely able to get in via some sort of
Comcast-specific protocol. This protocol might be in the generic firmware
because Comcast also happens to sell this particular device themselves, and
maintaining a single firmware image is probably easier for Motorola
logistically. I wonder if there are similar update channels for other ISPs on
the same device.

~~~
hackmiester
I believe it's pretty common for the customer equipment to be updated by the
ISP. I have an old modem-only Scientific Atlanta modem. If I start it up on
Comcast, the web GUI gets rebranded to Cisco, who now own SA. If I start it on
WideOpenWest, it isn't rebranded anymore, it says Scientific Atlanta on the
web GUI again.

~~~
uxp
For DOCSIS modems, they are only updatable and configurable via the ISP. When
you connect and power on your cable modem, it requests a configuration file
from someplace upstream. That config file contains the firmware version that
is compatible with both the network and the modem, and if they don't match
then it'll either ask upstream for a new firmware image or fail to connect to
the network.

Any configuration done by an end user is limited to the LAN portion of the
network. WAN should be cut off entirely.

------
paul_f
Last Sunday, Comcast, unbeknownst to me, and without my permission, turned on
a wifi hotspot in my house (in north Atlanta). Causing all sorts of wifi
connectivity problems. A new network appeared called xfinitywifi. Did Comcast
find a channel that didn't cause channel conflict? Of course not. Channel one.
Not knowing what Comcast was up to, I assumed my Airport had failed and spend
a couple hours swapping it for a new one. Of course, same problem. Finally
resolved the channel conflict and all is working Ok now. But thanks Comcast
for ruining my Sunday.

tl;dr Comsat did this to me. Learned how to change wifi channel on my router

~~~
graylights
I hope that it always defaults to channel one. That way in an apartment
complex all the xfinitywifi can conflict with eachother and at least leave
some channels open for real wifi networks.

------
Moral_
Interestingly enough, there is one of these in my apartment complex. I just
connected to it and it allows DNS requests through. You could connect to some
ones wifi and DNS tunnel out to the internet. Looks like there is a real easy
way to get free internet without giving a penny to CommieCast.

~~~
chacham15
It doesnt get you out of paying for internet: you still have to pay for the
other end of the DNS tunnel.

~~~
jjoonathan
Would you rather give your money to Amazon or to Comcast?

~~~
meowface
You can get away with spending $5/month to Amazon or a cheap VPS provider to
achieve the same kind of speeds you'd get from $60 to Comcast.

------
smoyer
This article is full of hyperbole and half-truth - I'm not a fan of Comcast
(my cable TV costs too much for the few channels I actually watch), but let's
get some facts straight.

There may be bandwidth bottlenecks in Comcast's network (the reason for the
NetFlix peering charges) but they're not between the fiber-optic transmitter
and the home. The HFC network (hybrid fiber-coax) has effectively seen a huge
increase in capacity due to the elimination of the analog channels (which
consumed 6MHz of bandwidth each). Each 6MHz channel now digitally carries
10-12 MPEG compressed channels.

The rest of the available bandwidth can be used for data transmission and with
the adoption of the MQAM, the same modulators can be switched between video
and data as bandwidth demands. SDV (Switched Digital Video) and DOCSIS 3.0
both help manage the infrastructure's efficency - you probably can't even use
all the bandwidth Comcast could provide from the head-end.

From the head-end to the Internet is another matter - because the large cable
operators grew through acquisition, it's uncommon to have similar data
capacities between their "systems". Since Comcast's backbone capacity is
miniscule in comparison to their "last mile" capacity, the real problem is
where to inject NetFlix data and how to transport that data to each head-end.
If NetFlix could peer into each Comcast head-end, this wouldn't even be an
issue.

(Disclaimer: 20 year CATV industry veteran now in higher education)

------
ghshephard
One correction to the article - The Comcast program is not "Opt-In" as the
article notes, but an "Opt-Out" program.

------
kator
Aren't they stealing electricity from these users?

It sounds like nothing but one of the ways laws developed around FAX machine
spam was judges said you were costing the end person real money in sheets of
paper. Certainly running the second WiFi has some small amount of additional
power requirement. I'm not sure it's even barely measurable but it is more
then zero which makes it like the fax paper reasoning.

~~~
tim333
I presume Comcast have put something in the small print of the terms and
conditions saying they are allowed to do that.

~~~
kator
Lawyers are notorious for not understanding the underlying things like this.
Could be the crack in their armor that they didn't see. It just takes a $5 per
customer class action suit to get their attention.

------
webkike
I'm actually connected to one of these hotspots right now. I had just moved in
to this new apartment and hadn't yet had time to set up internet. But lo and
behold there's this public network called "xfinitywifi", and my dad's comcast
account logs me in! Now, I dont think I'd like my own modem broadcasting a
hotspot, but it did turn out to be pretty convenient.

------
brudgers
IANAL

Generally in the US, the Owner of the property will own any improvements which
the cable company makes to the property unless their was an encumbrance on the
land title (or deed) - in which case their remedy for not allowing their use
of the improvement would be foreclosure but would be in line behind all
previously recorded encumbrances such as mortgages and covenants. This would
historically include anything buried or running through the walls. Overhead
wires also would likely fall in this category. Real property is funny that
way.

Contrary to the article's implication, the cable company could retain
ownership of the wire between the box and the wall socket. It's just
equipment, like the box itself. But the improvements to the land convey with
the land...if your neighbor builds his fence on your side of the property
line, it's not his fence it's yours. That's why the cable company cannot
insist you share your infrastructure.

~~~
banjomonster
IANAL either, but easements[1] may apply here, depending on how broadband
cable is classified.

And I'm not remembering the terms for this, but I've heard there are
situations where your neighbor building his fence on your land and you not
taking action within a certain amount of time would cede that part of your
land to your neighbor.

1\.
[https://en.wikipedia.org/wiki/Easement](https://en.wikipedia.org/wiki/Easement)

~~~
brudgers
Easements are a form of encumbrance upon a title. Though real estate law
varies by state in the US, access easements are typically the only form of
easement established by use...i.e. Passage across the property for physical
access to another property. Any other easement must typically be recorded.

Recording an easement requires paperwork at the courthouse, doc stamps, and
approval of any lien holders (such as a mortgager). The reason is that the
lien holder has a secured interest in the property secured by the title - that
they have joint ownership is the easiest way to think about it.

But rest assured, that if you build a fence on your neighbors side of the line
its his fence. You can have a contract that gives you the right to access it
and prohibits your neighbor from demolishing it, but it's with your neighbor
as an individual. If they sell the property the new owner owns the fence and
is not bound by the contract.

------
JamyDev
Here in Belgium they do the same, if you have one of their new DOCSIS3 modems
it is activated automatically. Although their hotspots are for their customers
only. If you disable it on your router you can't access other people's
hotspots. The speed is limited to 1Mbps per user so it wouldn't impact you
much, knowing that euro docs is can go up to 300 Mass (if not higher)

Personally I love it, it's perfect for when you're at a friends house and want
to check out something real quick.

------
opendais
I wouldn't be surprised if Comcast could effectively deliver 150mbps to all
subscribers on their network and just uses the excess capacity to provide
wifi. Of course that sucks if you paid for the full 150mbps. ;)

Of course, that doesn't mean where their network connects to the internet
won't get more congested...

~~~
noselasd
For cable, the other wifi network is served on a different docsis channel, and
shouldn't affect your speed - at least not the part from your router to the
other end of the cable.

~~~
opendais
Yes. But it probably doesn't help at the hop from their and onward.

~~~
noselasd
Well, the other end should be a Comcast central office, if they don't have the
necessary bandwidth backhaul, you have at least a very valid reason to
complain.

------
tim333
Bit off topic but I was reading up on FON who pioneered this stuff. Early
stuff (2005):

"At first, Varsavsky says, he "couldn't see a business model" in his idea.
"But I thought it could be a great thing. I thought, 'I'm going to develop
some firmware that people can download into their router.'" By November 2005,
Fon's firmware was ready. Users could install it on the hack-friendly Linksys
WRT54G router, which was built around Linux."

from
[http://www.wired.co.uk/magazine/archive/2011/09/features/ope...](http://www.wired.co.uk/magazine/archive/2011/09/features/open-
access-fon/viewall)

They now have about 12 million spots ( [http://gigaom.com/2014/05/20/fons-
crowdsourced-wi-fi-network...](http://gigaom.com/2014/05/20/fons-crowdsourced-
wi-fi-network-spreads-down-under-with-telstra-deal/) ) so doing ok but still a
minority thing

------
fiatpandas
Comcast should be paying property owners for the privilege of using their
building for a commercial/advertising service, deducting some percentage from
the monthly bill. There are various benefits Comcast receives from having this
turned on. They make their wifi coverage map larger and more competitive
thanks to your location. They wouldn't have that blip on the map if you
weren't paying property taxes.

Additionally, there is the profit benefit, assuming they will charge non-
subscribers when their free 10 minutes is up.

WiFi services are competitive because of coverage, and therefore geographic
location. When they are attached to buildings they need (small) amount of
power and physical protection. You're providing all of this to Comcast, for
free, to build their coverage network. I think compensation is warranted. In
more expensive areas, both in terms of rent and location-based taxes, this
becomes even more important of an issue.

~~~
jedbrown
The "rebate" has already been applied to your monthly bill. How much is it
worth to you to remove it?

------
bstar77
I live in NJ and I see an open (and extremely strong) XfinityWifi network
signal. I don't know if this is the default SSID with no security or one of
these public hotspots. But since Comcast has a corporate office a couple miles
from me, I wouldn't be surprised if they were experimenting with this lovely
service locally as well.

~~~
epoxyhockey
Comcast has large gray boxes installed on some telephone pole lines that are
wifi access points (with an ssid of _xfinitywifi_ ). They are installed in
many cities across the country (including in NJ) and can be found on this map:
[http://www.att.com/maps/wifi.html](http://www.att.com/maps/wifi.html) (ignore
the fact that this information is hosted on an att.com website)

~~~
jonny_eh
Can you explain the att.com and comcast angle? Are you saying that att.com
lists Comcast wifi hotspots?

------
zobzu
My ISP in EU does this and theres zero impact. Nobody ever connects - and if
they do they're quite capped. Capped enough that i couldnt tell the diff (but
they can check emails and view webpages so thats nice for them)

Of course, i agreed to this when subscribing so theres that - and in fact I
can turn it off if i want (its opt out)

~~~
leorocky
Can you tap the wire between that public hotspot and the wall and serve those
people upside down cat images (and snoop all their clear text traffic)?

~~~
cr3ative
I'm under the impression that the router forms a VPN tunnel to an endpoint at
the ISP (which is why public users have a different IP and their traffic is
easily proven not to be that of the subscribers)

------
jtokoph
FYI, the 'xfinitywifi' hotspots you've seen over the past couple years are
this same thing deployed via Comcast Business customers' modems.

------
zitterbewegung
Pretty sure they are doing this after you upgrade your modem. I have been
noticing this more and more with my iPhone. Gets sort of annoying though when
it keeps on trying to connect to these hotspots and basically causes my
internet to drop out due to it trying to connect.

------
lsh123
I would be curious to learn how this is done technically: would the "owner"
connections and public hotspot wifi connections share the same IP or not? If
the IP is shared then there will be some interesting issues to be resolved if
someone connects to a public hotspot, fires up Torrent client, downloads tons
of movies, and then the owner of the hotspot gets the takedown notice or there
will be charges against the owner for downloading copyrighted material. And
you can imagine other cases from child pornography to financing terrorists.

~~~
jsz0
Cable modems can be configured to support multiple service flows with
different classes of service. The users of the public hotspot network have a
unique IP and separate service flows provisioning additional bandwidth to the
modem. Presumably Comcast is also tracking an authenticated user's IP address
while on public hotspots for DMCA enforcement purposes.

~~~
jrockway
Though there's very little stopping you from setting up an access point called
"XfinityWifi" and connecting it to whatever evil you want.

~~~
jsz0
This is a very legitimate concern. I doubt Comcast or any other ISP using
these community wifi services are really prepared to deal with this problem.
Any Comcast customer who runs into problems with DMCA / legal issues (via IP)
will have plenty of reasonable doubt on their side.

------
chollier
Nice, what took them so long ? it's been like that and so useful (for
everyone) for years in France. Maybe one days the US will discover the EAP-SIM
"revolutionary thing" too

~~~
xroche
Can confirm - "Free Wifi" (from ISP Free) is pretty useful, because you can
find hostspots almost everywhere. (Too bad EAP-SIM isn't working on Android
without rooting the device, sheesh :p)

------
mclemme
A Danish company, yousee, did something like this, in an opt-out model. After
launching it nationwide, it was found that the two wireless networks were not
quite separate. IIRC only IPv4 traffic was separate.

Translated article:
[http://www.google.com/translate?hl=en&ie=UTF8&sl=da&tl=en&u=...](http://www.google.com/translate?hl=en&ie=UTF8&sl=da&tl=en&u=http%3A%2F%2Fwww.version2.dk%2Fartikel%2Fyousee-
lukker-hotspots-paa-grund-af-sikkerhedshul-57044)

While it was running, some people reported that not opting out and then
putting your cable model in bridge mode, would disable both wireless networks,
but allowing you to use the extra bandwidth for your own use. Didn't get to
try it myself before the feature was disabled due to the bug mentioned above.

------
boyaka
I don't like this, because it creates a network that users can connect to, on
YOUR property, that YOU don't control. Comcast is literally using the property
you own to spy on people that are near you. I assume that they are doing a lot
to control the traffic of individuals connecting to these hotspots.

~~~
jamesbrownuhh
Whoa! What? Who's "spying on people that are near you"?

And incidentally, what part of "the property you own" is being used here? The
cable modem, which isn't yours? The Comcast network, which you don't own? The
wireless spectrum, over which you have no exclusivity? Your IP connectivity,
which isn't affected?

I find it baffling that people can be so hugely resistant to such harmless
ideas. Seriously, where does that come from?

~~~
boyaka
I assume there is motivation for these large ISPs to provide internet access
(and thus additional bandwidth) for free at all of their customer's locations.
I assume there is some sort of profit being made from it, and I assume it has
something to do with finding out what/who is near these access points and
maybe seeing what they are doing and feeding them different sorts of data
based on that information.

The property you own that they are utilizing is just that, your property, or
your estate. They are using the land that you work your entire life to rent or
own to scan mobile devices around it and gather information which they are
profiting from.

I just think it is a stretch to go from a simple cable modem (which customers
could easily own, but they'd rather give away their natural right to control
their own property for ease of use/access) which should just simply be
providing access to the bandwidth you are paying for (like cable boxes would
just provide you a connection to your TV channels of choice), to operating an
internet service to anybody in your area.

~~~
jamesbrownuhh
Your opening paragraph starts with four assumptions, none of which are backed
up by any evidence. Why do you "assume" that Comcast are trying to "find out"
who/what is near those access points? What cause have you to "assume" that
they are "maybe seeing what they are doing"?

What is the basis of your claim that they are using this as a way to 'scan
mobile devices .. and gather information which they are profiting from'? What
information? Profiting how?

Without facts, what you're saying is indistinguishable from any other
conspiracy theory.

You say 'operating an internet service to anybody in your area' and in the
main it's not "anybody" \- it's Comcast customers. Of which you, if you are so
affected, are likely to be one. Comcast using their equipment, their
facilities, their network and their backhaul to operate an internet facility
to THEIR customers.

The long and the short of services like this is that people - where they have
a choice - are more likely to choose, or stay with, or be happier paying for,
an Internet Service Provider if they get more value from it. If your Comcast
internet service suddenly comes with the ability to access that service from
wifi hotspots throughout the town or city where you live [and there's a great
chance of there being a significant number of such hotspots available in a
locale served by a dominant cable operator] then you, as a Comcast customer,
are likely to get a good value from that.

Good value equals more and happier customers willing to keep paying the same
or more. Simple business. No covert data-gathering and "seeing what people are
doing" conspiracies required.

~~~
boyaka
I'm not just making up a cause for worrying about free hotspots...It may have
been conspiracy talk but there has been discussion about the ethics behind
them before. I think it's worth discussing what people are doing with the
power to control people's access to internet, especially when it seems like
Comcast is just shoving them into peoples homes.

Fact: Once you have a XfinityWIFI added to your device and wifi turned on, you
are automatically connecting to these hotspots.

Lots of customers don't understand the implication of this, which is that
Comcast knows where you are located.

Fact: You can see a lot more information about devices connected to the an
internet access point if you control the lowest routing layer. Just try
hooking up a router into another router, and try seeing the devices connected
to the first router on the second.

Giving Comcast control of routing the internet connection available on your
property is allowing them to see details about devices in the area, which they
would not see if they were simply providing you a single connection to a
router that you own. Sure, plenty of providers had wifi built into their
modems (all those crappy 2WIRE things), but at the very least the customer is
able to set a password and control who Comcast is able to see is near their
property. With this service it just seems like Comcast is making all it's
customer's homes a tracking point for everybody else.

Why should customers be able to access the internet at random locations based
on where other customers live? Isn't that what a mobile data connection is
for? Sure, the more hotspots available the better, I guess, but if comcast
wants to provide access to the internet it should create a technology that can
do it without using other people's property/land/estate, and without being
able to gather useful information about peoples' locations and maybe more
detailed device and network traffic information.

Also, I don't know much about analyzing a single network interface for
internet traffic from multiple users, like what we hear about the NSA doing at
major internet hubs, but I assume a lot of work needs to be done to filter
through information like that. I admit I don't have enough
knowledge/experience/evidence/facts about networking, even though I did study
computer engineering, but I will make an assumption (at least educated?) that
if you have control over the lowest layer of routing you can get a lot more
information about the activities taking place on the clients.

------
brianbreslin
How does this compare to FON wifi routers in Europe? There people share their
connection for revenue sharing.

~~~
icebraining
Not always; here in Portugal our biggest ISP started installing FON routers
for all their clients, but they don't get any of the revenue sharing, just
access to other FON routers.

------
tehwebguy
Brighthouse has been quietly doing something similar throughout central
Florida (at least) for a year or so. I only saw it at businesses and in the
cases I saw there were two separate modems.

My _guess_ is that there's no way this doesn't degrade the customers'
connection.

------
HenryMc
Telstra is planning on doing this in Australia.

[http://www.theaustralian.com.au/technology/telstra-phones-
ho...](http://www.theaustralian.com.au/technology/telstra-phones-home-to-
build-wifi-network/story-e6frgakx-1226924057245)

------
smutticus
I am not a Comcast customer, but have a simple question. Who owns the CPE
device(Xfinity Wifi router) that Comcast installs in people's homes? Does
Comcast own it, and subscribers agree to have it managed by Comcast? Or is it
owned by the subscribers?

~~~
Omniusaspirer
Comcast owns it, if people don't like it they should buy their own
modem/router and then it won't be an issue for them personally (and who
wouldn't buy their own router anyways?).

------
tim333
It's a shame Comcast seems to be rolling their own system rather than joining
the FON network. The great thing with FON in principle is that you can use it
around the world although in practice it doesn't work very well, in my
experience.

------
reustle
I'm pretty sure Time Warner has been doing this in NY for some time now

~~~
MichaelApproved
My area (Astoria, Queens) recently got upgraded to 300/20mbps but, to get that
speed, I needed to upgrade my modem. I wouldn't be surprised if this new modem
will have this capability. It's yet another reason to have your own router
behind their modem.

As long as my speed doesn't degrade and I'm using my own router behind the
modem, I don't mind if they make it a public hot spot.

Of course, most people use the cable companies modem as their wifi/router. I
wouldn't be surprised if people discover major security vulnerabilities in
these mix-public/private modems.

~~~
learc83
>As long as my speed doesn't degrade and I'm using my own router behind the
modem, I don't mind if they make it a public hot spot.

If your wireless router is near the modem and it's broadcasting on an
overlapping channel then it will definitely degrade your speed.

~~~
jrockway
First, if you care about wireless speed, you're not using 2.4GHz, you're using
5GHz. 5GHz channels do not overlap.

Second, other WiFi networks are not really the cause of interference.
Certainly, if two networks are sharing the same channel and both have stations
that want to use the full bandwidth at the same time, that won't work. But
WiFi does listen before it transmits, and does not transmit when it can hear
other stations transmitting. This lets many networks share the same channel.

Where this goes wrong is when two stations want to talk to the same access
point, but can't hear each other. (The "hidden node" problem.) In that case,
station A can't tell that station B is transmitting, and so station A might
transmit over station B's transmission, resulting in garbage at the access
point. (Access points that can both hear a station but not each other can also
do this, of course.)

In the scenario you mention, your own access point and Comcast's access point
are almost in the same place, so they should be able to hear the same set of
stations. If they pick the same channel (and autoselection _is_ notoriously
poor), they should not interfere except to share bandwidth.

Finally, there's so much crap in the 2.4GHz band already that another WiFi
network isn't going to make a difference. From my apartment I can hear 20+
WiFi networks, and if I look at a spectrum readout, can see tons of other
things that I have no idea what they are.
[https://plus.google.com/115192122236060613729/posts/RZHLmV5K...](https://plus.google.com/115192122236060613729/posts/RZHLmV5KPQH)

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learc83
>you're not using 2.4GHz, you're using 5GHz.

I was assuming these comcast modems were 2.4GHz. But you have a point, if
you're using a 5GHz router this problem is avoided.

>Finally, there's so much crap in the 2.4GHz band already that another WiFi
network isn't going to make a difference. From my apartment I can hear 20+
WiFi networks, and if I look at a spectrum readout, can see tons of other
things that I have no idea what they are.

That depends on where you live. At my house there are only 2 wireless networks
near enough to matter and I moved my network to a non-overlapping channel.
Also I use 2.4GHZ because 5GHz doesn't cover my entire house.

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iancarroll
I just installed a new modem to provide "higher speeds". Speed hasn't changed,
but we have a new wifi network (xfintywifi).

We do have the old equipment, but it's not that bad honestly.

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sergiotapia
I'm assuming Comcast pays the user for opting in to this service. Hah! Of
course not, when does the US government protect consumers from these telecom
behemoths.

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nkozyra
How exploitable is this concept? As a node, I should be privy to sensitive
data, if nefariously.

Seems like a couple of those incidents would bring this to a screeching halt.

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jrs235
I assume the NSA and government like this. More ways to determine the location
of devices (people) and ways to get onto those devices or data.

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higherpurpose
Are the hotspots free for anyone to use at least? Or do they intend on
charging for them, too? Because that would really be a dick move.

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nmrm
AFAIK the way it typically works is that subscribers to the ISP's service get
access for free, but others have to pay.

So if you're an xfinity customer, you can use their public wifi hotspots. But
if you're not an xfinity customer, you have to pay.

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jaachan
Either way you're paying...

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nmrm
Yes, I agree. I was just explaining how it works :)

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beedogs
Seems like a fantastic way to indemnify yourself against any charges of piracy
that are leveled at you and your Internet connection.

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josephpmay
What's even worse is that they're doing this for businesses, which can become
an obvious security disaster.

~~~
wmf
What part of it is a security disaster?

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yzzxy
Often the owner of an access point is liable for illegal traffic on it.

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MichaelApproved
The public hotspot will likely have a different IP than the "hosting"
business. At least, let's hope they would be smart enough to do that.

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snarfy
They can't stop you from putting their cable modem in a Faraday cage.

