12 ms·

What’s this xfinitywifi network and why do I keep connecting? (2016)

51 points by apsec112 7y ago

peter303 7y ago
Note for comcast customers: the default on your setup is devote one fifth of your modem capacity to general xfinity wifi. So the general public can surf porn at your expense. Xfinity has settings to turn this off. However like Facebook privacy, comcast continuously turns this back on.
- LeoPanthera 7y ago
  This is misleading. It doesn't share bandwidth on the cable with your internet connection. Removing it wouldn't make your interest faster.
  - lotsofpulp 7y ago
    Where is the bandwidth coming from? Coax in general is sharing bandwidth between the whole neighborhood, hence the piss poor upload speeds and latency. Obviously all bandwidth is shared at some point, but the extend to which coax is is ridiculous in my experience. They sell individuals hundreds of megabits download, 5 “megabit” upload, when the whole neighborhood might only have a few hundred megabits download capacity total. It’s a joke compared to symmetric fiber connections, and that they share even more of your connection with their xfinitywifi adds to that. Hence why one should always buy and use your own cable modem.
    - rayiner 7y ago
      This is a little bit off. Looking at an actual comcast channel map: https://pickmymodem.com/ofdm-sub-carrier-ranges-on-docsis-3-1-cable-modem https://pickmymodem.com/ofdm-sub-carrier-ranges-on-docsis-3-.... The 24 DOCSIS 3.0 channels are about a gigabit in the aggregate, and the 94 MHZ OFDM channel is about another gigabit. Compared to 2.4 gbps down for GPON. (GPON is a decade older tech, so not surprising.) There will be more people on a cable node than on a GPON (which is typically 16-32). But Comcast is N+0 on its DOCSIS 3.1 footprint (which is 75% of its network). That means they’ve removed amplifiers that extend the signal of the cable over distances, because those amplifiers get in the way of more aggressive techniques used in DOCSIS 3.1. That requires pushing fiber deeper into the network, and has the side effect of reducing how many subscribers are in each shared bus. The upload limits are more an issue of legacy channel maps than insufficient bandwidth on the wire. The upstream/downstream portions are separated into different portions of the RF spectrum, and for historical reasons the split is heavily biased toward downstream. But symmetric DOCSIS is around the corner. There is also a lot of headroom left in DOCSIS 3.1. Compatible cable modems must support a minimum 192 MHz OFDM channels, which is almost 4 gbps. 10 gbps is possible if all the bandwidth on the coax is used for data rather than TV.
      - lotsofpulp 7y ago
        Appreciate the information regarding specs. My observations are from repeated exposures on east and west coast of US to Comcast cable connections, which are noticeably slower in the evening when there is more network congestion, and have terrible latency. Various speed tests give me only a fraction of advertised bandwidth, and even then, it won’t be sustained. It feels like they’ve programmed the system to allow new connections to have a burst of bandwidth, and then taper it down. I have yet to experience a coax internet experience as reliable and pleasant to use as a symmetric fiber connection. I presume it’s because Comcast is overselling their capacity, because they’re Comcast.
        mikeash 7y ago
        Your feeling is spot on. They definitely burst to a higher speed at the beginning of a transfer. What’s really amazing is that they’re proud of it! https://corporate.comcast.com/comcast-voices/what-is-powerboost https://corporate.comcast.com/comcast-voices/what-is-powerbo...
        rayiner 7y ago
        Apple and Intel seem pretty proud of their burst speeds too. (And battery life, which is quoted based on running the CPU at short bursts and then going idle.) And why shouldn’t they be? Consumer tech is properly optimized for burst usage. The network delivers the 10MB home page in a burst, then goes idle. The CPU bursts to 4 GHz to render it as fast as possible, then goes idle. The battery delivers 35W for half a second, then drops down to 5W. The whole system is designed around that usage profile.
        mikeash 7y ago
        The difference is that CPUs burst above the speed they can sustain. The alternative would be running slower all the time. Comcast, in contrast, just lets you use more of their otherwise idle capacity, then throttles you. The alternative would be getting the full capacity of their network all the time.
- skinnymuch 7y ago
  Can you show where this is true? I’ve been trying to get the WiFi part enabled. Have had a hard time on current and last router. The opposite of it being enabled by default.
- u801e 7y ago
  Does this apply if you're using your own modem/router?
  - colanderman 7y ago
    No. (Source: I've used my own modem & router with Comcast. There's no physical way they can force your router to host an xfinitywifi SSID.)
  - MrMember 7y ago
    I bought my own modem and router specifically to not deal with this garbage.
m463 7y ago
Nothing I hate more than devices auto-connecting to "partner wifi". One day my phone browsing was interrupted by a starbucks terms-and-conditions webpage. wtf? Turns out my phone had auto-connected to an attwifi access point in range. What's more disturbing is that companies work with "smart device" manufacturers so they can connect this way without you ever knowing. What if your smart tv, only ever plugged into HDMI, was connecting to your neighbor's xfinitywifi without you knowing it?
- paulcole 7y ago
  > What if your smart tv, only ever plugged into HDMI, was connecting to your neighbor's xfinitywifi without you knowing it? If this is the sort of thing I’m ever willing to wring my hands over and give more than 1/2 second of thought to, then I will thank God for how easy and cushy my life has become.
  - cameronbrown 7y ago
    Your Smart TV with integrated microphone array, sometimes a camera, potential for detecting location, potential WiFi sniffing tools and full access to the internet which you didn't grant? Oh and targeted ads right in the UI - so we know there's an incentive for them to do these things.
    - deleted 7y ago
      [deleted]
  - skinnymuch 7y ago
    What I feel about many of the things Some on HN go over the top over like it’s the biggest injustice. Though not necessarily this.
- briandear 7y ago
  In iOS 11+ you can disable this behavior.
  - 7y ago
sl1ck731 7y ago
This is especially annoying when it hops onto a 1 bar xfinity WiFi that barely works at all, or one that I just passed by at 60 mph, instead of just using 4G. I could never get my S6 to stop connecting to them, even after doing "forget this network". Thankfully I've replaced it. I understand what they're going for, but I'd rather have some kind of app manage it in such a way that it requires a certain strength and for me to be in the vicinity for more than a microsecond.
altmind 7y ago
xfinitywifi is free for anyone who already have xfinity at home. its extemely useful when you have a local internet outage. they are great because they authenticate with login/password only once and then remember the mac addr, you dont have to log in ever again. hope they wont start charging for this.
- mercantile 7y ago
  Agreed with this. Comcast is a terrible company in pretty much every way, shape, and form, but xfinitywifi has been useful to me many times now as a usable fallback when nothing else is available. Better OS-level tools to manage these connections (i.e. intelligently not connect and flag as degraded) when the signal or backing network is extremely weak would be a huge boon though.
- owl57 7y ago
  So, someone can just spoof that mac address and have their activity logged as yours? What could possibly go wrong?
  - deleted 7y ago
    [deleted]
  - markovbot 7y ago
    Yep! Last I checked (which admittedly was a while ago), 00:00:00:00:00:01 was valid for xfinitywifi
  - asveikau 7y ago
    I feel like it could also have bad legal consequences to have your MAC associated with an xfinity account. What if somebody spoofs your MAC and does sketchy illegal things? Similar to anecdotal stories I heard about people running TOR relays and subsequently hearing from law enforcement.
    - owl57 7y ago
      Thinking about this again, there's a bit of difference: most people running a Tor exit node probably made a conscious decision to take this risk.
jchw 7y ago
>Users aren’t reducing your internet speed any more than a new neighbor signing up for Comcast. The technical capability of their cable network is far faster than the speed Comcast doles out to you, since you pay for a throttled speed tier. The xfinitywifi network users aren’t included in your throttled speed. Is this actually true? I mean sure, DOCSIS 3.1 is capable of gigabit speeds in theory. But are the CPU and other resources on the modem/router actually _fully_ isolated? And coaxial cables that were laid decades ago, are they actually capable of reaching speeds fast enough to totally isolate you from bandwidth issues? Some people fail to hit their advertised speeds as is. My guess is that the reality is, you do lose some performance and gain some latency if there's a lot of xfinitywifi traffic going through your router. I am a Comcast customer, reluctantly, as pretty much any other Comcast customer, but I use my own hardware always. I don't like what Comcast is doing here, especially because they're not really telling you about it. Of course, as you would expect, you don't get any discount for what you are doing for them either, it's just part of life if you rent equipment, which eventually costs more than it saves anyways. But even if you buy your own hardware, trying to feel in control can be very hard. I used to use a MikroTik hAPlite as a router, but it got hacked a couple of times, and many more vulnerabilities eventually turned me off of MikroTik products despite how nice they were to use. Then I moved to one of the actually-kinda-expensive Linksys AC2600 and boy did that stuff piss me off royally. On top of the annoying 'smart' features, including a click through EULA and requiring online registration to access my own router's configuration menu, it honestly performed terribly. Being in an apartment, I connect my desktop via WiFi, and this thing couldn't even keep a stable connection for that. Some devices wouldn't connect at all, and I never figured out why, after hours of looking through logs and troubleshooting; the hAPlite had no such issues. So... I gave in. Surfboard SB82000 modem, Ubiquity Unifi AC and USG, and Cisco switches. It isn't cheap, and frankly it's completely ridiculous overkill. It's gotta be like, $500 worth of crap new, and it does require some additional setup, like having a machine setup to act as the controller. But, I rest a lot easier, and I have literally not had a single issue since configuring everything. Which is definitely more than I can say for any Comcast-installed equipment I've had to deal with. Good riddance. I hope some day there's a 'sane' option for people who just want good performance, good security for home use cases, but right now I'm wondering if there will ever be anything aimed at consumers that isn't trying super hard to exploit the crap out of them. The situation with consumer internet equipment has left me very jaded, especially because I remember running DD-WRT on a WRT54G and having a great time. Edit: It is worth noting that I never tried any of the whole home mesh WiFi solutions. I’ve heard good things, but apartments seem like unideal places to install them.
lebrad 7y ago
Comcast piggybacked an xfinitywifi hotspot on the Comcast Business router they installed for me. When I asked Comcast to turn off the hotspot, they told me to disable xfinitywifi using the Comcast Business web-based administration page. However, toggling the options on the page failed to disable their hotspot. Comcast said that I had discovered a bug, and that as a workaround they could disable the hotspot manually from their end. This also failed to work. In the end, I had them replace the router with a much older wired-only model.
- beauzero 7y ago
  Seriously had the same experience.
Fnoord 7y ago
Answer: Free WLAN for Comcast customers (USA cable telco). Just like KPN Fon, Ziggo, EMS Hotspot, and Wifi in de trein in The Netherlands, and very likely a plethora of other countries and businesses have such a feature as well. Use with a VPN, and you can make it secure. With Wireguard, you can make it reliable. Other than that, I'd be careful for MITM attacks.
Spare_account 7y ago
iOS: While in range of the xfinitywifi network, tap Settings > Wi-Fi. Tap the (i) to the right of the xfinitywifi network. Tap “Forget this network” Is it still the case that you can't 'Forget' a Wifi network on iPhone devices unless you're in range of the network? I recall this being a fact when I had an iPhone some time ago.
- masklinn 7y ago
  Yeah. AFAIK there's no way to access a list of all known networks.
- kalleboo 7y ago
  > Is it still the case that you can't 'Forget' a Wifi network on iPhone devices unless you're in range of the network? AFAIK, yes. The only exception is if you have a Mac logged into the same iCloud account, you can forget it on the Mac which does have a full list (and WiFi credentials are synced)
thrower123 7y ago
One of the main reasons I bought my own modem rather than using the one Comcast provides is to avoid broadcasting this terrible xfinitywifi network. It's not worth the liability.

51 points by apsec112 7y ago

Note for comcast customers: the default on your setup is devote one fifth of your modem capacity to general xfinity wifi. So the general public can surf porn at your expense. Xfinity has settings to turn this off. However like Facebook privacy, comcast continuously turns this back on.

LeoPanthera 7y ago
This is misleading. It doesn't share bandwidth on the cable with your internet connection. Removing it wouldn't make your interest faster.
- lotsofpulp 7y ago
  Where is the bandwidth coming from? Coax in general is sharing bandwidth between the whole neighborhood, hence the piss poor upload speeds and latency. Obviously all bandwidth is shared at some point, but the extend to which coax is is ridiculous in my experience. They sell individuals hundreds of megabits download, 5 “megabit” upload, when the whole neighborhood might only have a few hundred megabits download capacity total. It’s a joke compared to symmetric fiber connections, and that they share even more of your connection with their xfinitywifi adds to that. Hence why one should always buy and use your own cable modem.
  - rayiner 7y ago
    This is a little bit off. Looking at an actual comcast channel map: https://pickmymodem.com/ofdm-sub-carrier-ranges-on-docsis-3-1-cable-modem https://pickmymodem.com/ofdm-sub-carrier-ranges-on-docsis-3-.... The 24 DOCSIS 3.0 channels are about a gigabit in the aggregate, and the 94 MHZ OFDM channel is about another gigabit. Compared to 2.4 gbps down for GPON. (GPON is a decade older tech, so not surprising.) There will be more people on a cable node than on a GPON (which is typically 16-32). But Comcast is N+0 on its DOCSIS 3.1 footprint (which is 75% of its network). That means they’ve removed amplifiers that extend the signal of the cable over distances, because those amplifiers get in the way of more aggressive techniques used in DOCSIS 3.1. That requires pushing fiber deeper into the network, and has the side effect of reducing how many subscribers are in each shared bus. The upload limits are more an issue of legacy channel maps than insufficient bandwidth on the wire. The upstream/downstream portions are separated into different portions of the RF spectrum, and for historical reasons the split is heavily biased toward downstream. But symmetric DOCSIS is around the corner. There is also a lot of headroom left in DOCSIS 3.1. Compatible cable modems must support a minimum 192 MHz OFDM channels, which is almost 4 gbps. 10 gbps is possible if all the bandwidth on the coax is used for data rather than TV.
    - lotsofpulp 7y ago
      Appreciate the information regarding specs. My observations are from repeated exposures on east and west coast of US to Comcast cable connections, which are noticeably slower in the evening when there is more network congestion, and have terrible latency. Various speed tests give me only a fraction of advertised bandwidth, and even then, it won’t be sustained. It feels like they’ve programmed the system to allow new connections to have a burst of bandwidth, and then taper it down. I have yet to experience a coax internet experience as reliable and pleasant to use as a symmetric fiber connection. I presume it’s because Comcast is overselling their capacity, because they’re Comcast.
      - mikeash 7y ago
        Your feeling is spot on. They definitely burst to a higher speed at the beginning of a transfer. What’s really amazing is that they’re proud of it! https://corporate.comcast.com/comcast-voices/what-is-powerboost https://corporate.comcast.com/comcast-voices/what-is-powerbo...
        rayiner 7y ago
        Apple and Intel seem pretty proud of their burst speeds too. (And battery life, which is quoted based on running the CPU at short bursts and then going idle.) And why shouldn’t they be? Consumer tech is properly optimized for burst usage. The network delivers the 10MB home page in a burst, then goes idle. The CPU bursts to 4 GHz to render it as fast as possible, then goes idle. The battery delivers 35W for half a second, then drops down to 5W. The whole system is designed around that usage profile.
        mikeash 7y ago
        The difference is that CPUs burst above the speed they can sustain. The alternative would be running slower all the time. Comcast, in contrast, just lets you use more of their otherwise idle capacity, then throttles you. The alternative would be getting the full capacity of their network all the time.
skinnymuch 7y ago
Can you show where this is true? I’ve been trying to get the WiFi part enabled. Have had a hard time on current and last router. The opposite of it being enabled by default.
u801e 7y ago
Does this apply if you're using your own modem/router?
- colanderman 7y ago
  No. (Source: I've used my own modem & router with Comcast. There's no physical way they can force your router to host an xfinitywifi SSID.)
- MrMember 7y ago
  I bought my own modem and router specifically to not deal with this garbage.

m463 7y ago

Nothing I hate more than devices auto-connecting to "partner wifi". One day my phone browsing was interrupted by a starbucks terms-and-conditions webpage. wtf? Turns out my phone had auto-connected to an attwifi access point in range. What's more disturbing is that companies work with "smart device" manufacturers so they can connect this way without you ever knowing. What if your smart tv, only ever plugged into HDMI, was connecting to your neighbor's xfinitywifi without you knowing it?

paulcole 7y ago
> What if your smart tv, only ever plugged into HDMI, was connecting to your neighbor's xfinitywifi without you knowing it? If this is the sort of thing I’m ever willing to wring my hands over and give more than 1/2 second of thought to, then I will thank God for how easy and cushy my life has become.
- cameronbrown 7y ago
  Your Smart TV with integrated microphone array, sometimes a camera, potential for detecting location, potential WiFi sniffing tools and full access to the internet which you didn't grant? Oh and targeted ads right in the UI - so we know there's an incentive for them to do these things.
  - deleted 7y ago
    [deleted]
- skinnymuch 7y ago
  What I feel about many of the things Some on HN go over the top over like it’s the biggest injustice. Though not necessarily this.
briandear 7y ago
In iOS 11+ you can disable this behavior.
- 7y ago

sl1ck731 7y ago

This is especially annoying when it hops onto a 1 bar xfinity WiFi that barely works at all, or one that I just passed by at 60 mph, instead of just using 4G. I could never get my S6 to stop connecting to them, even after doing "forget this network". Thankfully I've replaced it. I understand what they're going for, but I'd rather have some kind of app manage it in such a way that it requires a certain strength and for me to be in the vicinity for more than a microsecond.

altmind 7y ago

xfinitywifi is free for anyone who already have xfinity at home. its extemely useful when you have a local internet outage. they are great because they authenticate with login/password only once and then remember the mac addr, you dont have to log in ever again. hope they wont start charging for this.

mercantile 7y ago
Agreed with this. Comcast is a terrible company in pretty much every way, shape, and form, but xfinitywifi has been useful to me many times now as a usable fallback when nothing else is available. Better OS-level tools to manage these connections (i.e. intelligently not connect and flag as degraded) when the signal or backing network is extremely weak would be a huge boon though.
owl57 7y ago
So, someone can just spoof that mac address and have their activity logged as yours? What could possibly go wrong?
- deleted 7y ago
  [deleted]
- markovbot 7y ago
  Yep! Last I checked (which admittedly was a while ago), 00:00:00:00:00:01 was valid for xfinitywifi
- asveikau 7y ago
  I feel like it could also have bad legal consequences to have your MAC associated with an xfinity account. What if somebody spoofs your MAC and does sketchy illegal things? Similar to anecdotal stories I heard about people running TOR relays and subsequently hearing from law enforcement.
  - owl57 7y ago
    Thinking about this again, there's a bit of difference: most people running a Tor exit node probably made a conscious decision to take this risk.

jchw 7y ago

>Users aren’t reducing your internet speed any more than a new neighbor signing up for Comcast. The technical capability of their cable network is far faster than the speed Comcast doles out to you, since you pay for a throttled speed tier. The xfinitywifi network users aren’t included in your throttled speed. Is this actually true? I mean sure, DOCSIS 3.1 is capable of gigabit speeds in theory. But are the CPU and other resources on the modem/router actually _fully_ isolated? And coaxial cables that were laid decades ago, are they actually capable of reaching speeds fast enough to totally isolate you from bandwidth issues? Some people fail to hit their advertised speeds as is. My guess is that the reality is, you do lose some performance and gain some latency if there's a lot of xfinitywifi traffic going through your router. I am a Comcast customer, reluctantly, as pretty much any other Comcast customer, but I use my own hardware always. I don't like what Comcast is doing here, especially because they're not really telling you about it. Of course, as you would expect, you don't get any discount for what you are doing for them either, it's just part of life if you rent equipment, which eventually costs more than it saves anyways. But even if you buy your own hardware, trying to feel in control can be very hard. I used to use a MikroTik hAPlite as a router, but it got hacked a couple of times, and many more vulnerabilities eventually turned me off of MikroTik products despite how nice they were to use. Then I moved to one of the actually-kinda-expensive Linksys AC2600 and boy did that stuff piss me off royally. On top of the annoying 'smart' features, including a click through EULA and requiring online registration to access my own router's configuration menu, it honestly performed terribly. Being in an apartment, I connect my desktop via WiFi, and this thing couldn't even keep a stable connection for that. Some devices wouldn't connect at all, and I never figured out why, after hours of looking through logs and troubleshooting; the hAPlite had no such issues. So... I gave in. Surfboard SB82000 modem, Ubiquity Unifi AC and USG, and Cisco switches. It isn't cheap, and frankly it's completely ridiculous overkill. It's gotta be like, $500 worth of crap new, and it does require some additional setup, like having a machine setup to act as the controller. But, I rest a lot easier, and I have literally not had a single issue since configuring everything. Which is definitely more than I can say for any Comcast-installed equipment I've had to deal with. Good riddance. I hope some day there's a 'sane' option for people who just want good performance, good security for home use cases, but right now I'm wondering if there will ever be anything aimed at consumers that isn't trying super hard to exploit the crap out of them. The situation with consumer internet equipment has left me very jaded, especially because I remember running DD-WRT on a WRT54G and having a great time. Edit: It is worth noting that I never tried any of the whole home mesh WiFi solutions. I’ve heard good things, but apartments seem like unideal places to install them.

lebrad 7y ago

Comcast piggybacked an xfinitywifi hotspot on the Comcast Business router they installed for me. When I asked Comcast to turn off the hotspot, they told me to disable xfinitywifi using the Comcast Business web-based administration page. However, toggling the options on the page failed to disable their hotspot. Comcast said that I had discovered a bug, and that as a workaround they could disable the hotspot manually from their end. This also failed to work. In the end, I had them replace the router with a much older wired-only model.

beauzero 7y ago
Seriously had the same experience.

Fnoord 7y ago

Answer: Free WLAN for Comcast customers (USA cable telco). Just like KPN Fon, Ziggo, EMS Hotspot, and Wifi in de trein in The Netherlands, and very likely a plethora of other countries and businesses have such a feature as well. Use with a VPN, and you can make it secure. With Wireguard, you can make it reliable. Other than that, I'd be careful for MITM attacks.

Spare_account 7y ago

iOS: While in range of the xfinitywifi network, tap Settings > Wi-Fi. Tap the (i) to the right of the xfinitywifi network. Tap “Forget this network” Is it still the case that you can't 'Forget' a Wifi network on iPhone devices unless you're in range of the network? I recall this being a fact when I had an iPhone some time ago.

masklinn 7y ago
Yeah. AFAIK there's no way to access a list of all known networks.
kalleboo 7y ago
> Is it still the case that you can't 'Forget' a Wifi network on iPhone devices unless you're in range of the network? AFAIK, yes. The only exception is if you have a Mac logged into the same iCloud account, you can forget it on the Mac which does have a full list (and WiFi credentials are synced)

thrower123 7y ago

One of the main reasons I bought my own modem rather than using the one Comcast provides is to avoid broadcasting this terrible xfinitywifi network. It's not worth the liability.