Re: [tcpm] Privacy problems of TCP Fast Open
Michael Tuexen <michael.tuexen@lurchi.franken.de> Tue, 21 May 2019 10:18 UTC
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From: Michael Tuexen <michael.tuexen@lurchi.franken.de>
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Date: Tue, 21 May 2019 12:18:48 +0200
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To: sy@informatik.uni-hamburg.de
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Subject: Re: [tcpm] Privacy problems of TCP Fast Open
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> On 21. May 2019, at 09:52, Erik Sy <sy@informatik.uni-hamburg.de> wrote: > > Hi Michael, > > thanks for this question! > > Yes, TFO cookies are bound to the clients (local) IP address. However, a > client with a static local IP address in a home network will use the > same TFO cookie independently of it's publicly visible IP address. As a > result, TFO cookies present an independent tracking mechanism, which > does not necessarily rely on the client's publicly visible IP address. How often do the public addresses change? One could extend the TFO API in a way that the application can request a new cookie by only sending a cookie request. > > Returning to your example, onion routing does not necessarily protect > you against tracking via TFO cookies. Yepp, that is what I wanted to say. But using TFO in that case doesn't make much sense. Best regards Michael > > Best regards, > Erik > > On 5/21/19 09:13, Michael Tuexen wrote: >>> On 20. May 2019, at 23:19, Erik Sy <sy@informatik.uni-hamburg.de> wrote: >>> >>> I think it is important to warn users about the privacy risks of RFC >>> 7413. For example, Mozilla reacted to the privacy problems of TCP Fast >>> Open by deprecating this protocol on all it's Firefox branches. In >>> total, TCP Fast Open has significant issues with respect to user >>> privacy, performance and deployment on the real-world Internet. From my >>> point of view, it is about time to deprecate RFC 7413. >> Hi Eric, >> >> my understanding is that a cookie is specific to a client address, a server >> address and a server port. So it would make sense for a client to remove >> entries from the cookie cache on an address change. Assuming that, how >> does your described host based attacks relate to the server just using >> the client IP address for tracking? If you are trying to hide you IP-address >> (like using a TOR browser) you don't want to use TFO, but you are not >> optimising for small RTTs in that case, so it makes no sense in that case. >> >> Best regards >> Michael >>> Regards, >>> Erik >>> >>> On 5/10/19 14:14, Erik Sy wrote: >>> >>>> Hi everyone, >>>> >>>> TCP Fast Open has significant privacy problems which are not considered >>>> in RFC 7413. >>>> For example, this protocol allows a passive network observer to >>>> correlate connections established by the same client, which protocols >>>> such as TLS 1.3 and QUIC actively protect against. Furthermore, Fast >>>> Open cookies present a kernel-based tracking mechanism which is quite >>>> persistent. Amongst others, they can be used to conduct cross-browser >>>> tracking on the same operating system. >>>> For further details please refer to this article: >>>> https://arxiv.org/pdf/1905.03518.pdf >>>> >>>> I suggest, that the working group takes steps to highlight these privacy >>>> problems of RFC 7413. >>>> >>>> Regards, >>>> Erik >>>> >>>> _______________________________________________ >>>> tcpm mailing list >>>> tcpm@ietf.org >>>> https://www.ietf.org/mailman/listinfo/tcpm >>> _______________________________________________ >>> tcpm mailing list >>> tcpm@ietf.org >>> https://www.ietf.org/mailman/listinfo/tcpm
- [tcpm] Privacy problems of TCP Fast Open Erik Sy
- Re: [tcpm] Privacy problems of TCP Fast Open Erik Sy
- Re: [tcpm] Privacy problems of TCP Fast Open Michael Tuexen
- Re: [tcpm] Privacy problems of TCP Fast Open Erik Sy
- Re: [tcpm] Privacy problems of TCP Fast Open Michael Welzl
- Re: [tcpm] Privacy problems of TCP Fast Open Michael Tuexen
- Re: [tcpm] Privacy problems of TCP Fast Open Erik Sy
- Re: [tcpm] Privacy problems of TCP Fast Open Brian Trammell (IETF)
- Re: [tcpm] Privacy problems of TCP Fast Open Michael Tuexen
- Re: [tcpm] Privacy problems of TCP Fast Open Michael Tuexen
- Re: [tcpm] Privacy problems of TCP Fast Open Praveen Balasubramanian
- Re: [tcpm] Privacy problems of TCP Fast Open Erik Sy
- Re: [tcpm] Privacy problems of TCP Fast Open Michael Tuexen
- Re: [tcpm] Privacy problems of TCP Fast Open Erik Sy
- Re: [tcpm] Privacy problems of TCP Fast Open Erik Sy
- Re: [tcpm] Privacy problems of TCP Fast Open Michael Welzl
- Re: [tcpm] Privacy problems of TCP Fast Open Olivier Bonaventure
- Re: [tcpm] Privacy problems of TCP Fast Open Erik Sy
- Re: [tcpm] Privacy problems of TCP Fast Open Praveen Balasubramanian
- Re: [tcpm] Privacy problems of TCP Fast Open Michael Tuexen
- Re: [tcpm] Privacy problems of TCP Fast Open Erik Sy
- Re: [tcpm] Privacy problems of TCP Fast Open Michael Tuexen
- Re: [tcpm] Privacy problems of TCP Fast Open Erik Sy
- Re: [tcpm] Privacy problems of TCP Fast Open Michael Tuexen