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How do they know that single computer isn't doing DHCP/NAT for other computers? Are they doing nmap OS fingerprinting and banking off the assumption that peopl

How do they know that single computer isn't doing DHCP/NAT for other computers? Are they doing nmap OS fingerprinting and banking off the assumption that people using Windows/OSX wouldn't be doing that, but people using Linux might be?

ghshephard 15y ago
NAT basically doesn't exist in the IPv6 world. Realize that Comcast is optimizing for the 95% of their customer base that just wants something to work. Clearly their will be another 5% that will always go off the beaten path - and will likely be responsible for their own support.
- burgerbrain 15y ago
  I understand that. I'm wondering how Comcast would be able to selectively roll this out. How do they know the person who has a single computer connected directly to the modem doesn't have more computers behind it? Since they would currently be using IPv4, I would say NAT is a very real possibility.
  - ghshephard 15y ago
    There are two perspective here. One is what Comcast is prepared to support - and they've identified a minimally useful environment, that allows them to start off slowly, and eliminates as many possible variables from the equation as they can. No /48 routing, (no routers on the CPE at all), no proxying, no RFC 4193, no stateless auto configuration, no 4941 privacy extension. That is from the perspective of Comcast and what they'll support. Then, there is the perspective of what the end user can do (with or without telling comcast) - obviously, in the IPv4 case, you can PAT/NAT to your heart's content, and Comcast will be none the wiser. So - depending on whether you want to stay within the confines of what Comcast is "officially" supporting, or working with the realm of what you know will work - you may or may not want to NAT4 (I personally would have no problems doing it) Which brings us back to the question of IPv6 - I don't think there is any mechanism to allow multiple hosts to hide behind a single IPv6 address, so, from that perspective, the "What will Comcast support" and "What will I do" - turn out to be the same perspective. :-)
    - X-Istence 15y ago
      You can run NAT using IPv6 without issues using OpenBSD's pf firewall for example, so yes, you can "hide" multiple hosts behind a single IPv6 address.
      - trout 15y ago
        There aren't any widely deployed standards for NAT66. There are some drafts and ideas, but nothing commercially standard. I'd be hesitant to trust these implementations. You're better off using a firewall than a half-baked IPv6 NAT at this point.
        X-Istence 15y ago
        I was simply pointing out that an implementation exists. Whether it is complete or not I can't speak to because I haven't used it. Although, I do tend to trust the OpenBSD crew when it comes to implementing functioning code.
- deleted 15y ago
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ghshephard 15y ago

NAT basically doesn't exist in the IPv6 world. Realize that Comcast is optimizing for the 95% of their customer base that just wants something to work. Clearly their will be another 5% that will always go off the beaten path - and will likely be responsible for their own support.

burgerbrain 15y ago
I understand that. I'm wondering how Comcast would be able to selectively roll this out. How do they know the person who has a single computer connected directly to the modem doesn't have more computers behind it? Since they would currently be using IPv4, I would say NAT is a very real possibility.
- ghshephard 15y ago
  There are two perspective here. One is what Comcast is prepared to support - and they've identified a minimally useful environment, that allows them to start off slowly, and eliminates as many possible variables from the equation as they can. No /48 routing, (no routers on the CPE at all), no proxying, no RFC 4193, no stateless auto configuration, no 4941 privacy extension. That is from the perspective of Comcast and what they'll support. Then, there is the perspective of what the end user can do (with or without telling comcast) - obviously, in the IPv4 case, you can PAT/NAT to your heart's content, and Comcast will be none the wiser. So - depending on whether you want to stay within the confines of what Comcast is "officially" supporting, or working with the realm of what you know will work - you may or may not want to NAT4 (I personally would have no problems doing it) Which brings us back to the question of IPv6 - I don't think there is any mechanism to allow multiple hosts to hide behind a single IPv6 address, so, from that perspective, the "What will Comcast support" and "What will I do" - turn out to be the same perspective. :-)
  - X-Istence 15y ago
    You can run NAT using IPv6 without issues using OpenBSD's pf firewall for example, so yes, you can "hide" multiple hosts behind a single IPv6 address.
    - trout 15y ago
      There aren't any widely deployed standards for NAT66. There are some drafts and ideas, but nothing commercially standard. I'd be hesitant to trust these implementations. You're better off using a firewall than a half-baked IPv6 NAT at this point.
      - X-Istence 15y ago
        I was simply pointing out that an implementation exists. Whether it is complete or not I can't speak to because I haven't used it. Although, I do tend to trust the OpenBSD crew when it comes to implementing functioning code.
deleted 15y ago
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