Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt
"Anantha Ramaiah (ananth)" <ananth@cisco.com> Mon, 29 September 2008 17:41 UTC
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Thread-Topic: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt
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From: "Anantha Ramaiah (ananth)" <ananth@cisco.com>
To: Ted Faber <faber@ISI.EDU>
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Cc: rrs@cisco.com, tcpm@ietf.org, David Borman <david.borman@windriver.com>, "Mitesh Dalal (mdalal)" <mdalal@cisco.com>
Subject: Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt
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> > The paragraph I'm commenting on reads: > > A third type of attack is also highlighted by both the RST and SYN > attacks. It is also possible to inject data into a TCP > connection by > simply guessing a sequence number within the current receive window > of the victim. The ACK value of any data segment is > considered valid > as long as it does not acknowledge data ahead of the next > segment to > send. In other words an ACK value is acceptable if it is > ((SND.UNA- > (2^31-1)) <= SEG.ACK <= SND.NXT). The (2^31 - 1) in the above > inequality takes into account the fact that comparisons on TCP > sequence and acknowledgement numbers is done using the > modulo 32 bit > arithmetic to accommodate the number wraparound. This > means that an > attacker has to guess two ACK values with every guessed sequence > number so that the chances of successfully injecting data into a > connection are 1 in ((2^32 / RCV.WND) * 2). > > I'm saying that, assuming the math is correct, that last > expression should be (2^33 / RCV.WND). I didn't check the > math. If you also believe the math is wrong, you have a > larger edit. :-) > > On rereading the argument, it does sound like a data > injection attack should be harder by a factor of 2 and that > they multiplied by the wrong expression (2^32 rather than > 2^31). So I think you're correct about the math, and if so > the final expression would be 2^32 / RCV.WND. > > I'd be happier if someone else also looked at this paragraph > for technical accuracy. I have updated the document with the correct math. I agree that it would be nice if a few more folks take a look. Thanks, Anantha > > -- > Ted Faber > http://www.isi.edu/~faber PGP: > http://www.isi.edu/~faber/pubkeys.asc > Unexpected attachment on this mail? See > http://www.isi.edu/~faber/FAQ.html#SIG > _______________________________________________ tcpm mailing list tcpm@ietf.org https://www.ietf.org/mailman/listinfo/tcpm
- [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt David Borman
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Fernando Gont
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Anantha Ramaiah (ananth)
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Fernando Gont
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Fernando Gont
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Anantha Ramaiah (ananth)
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Ted Faber
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt David Borman
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt David Borman
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Eddy, Wesley M. (GRC-RCN0)[VZ]
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt David Borman
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt David Borman
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt David Borman
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Anantha Ramaiah (ananth)
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt David Borman
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Ted Faber
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Ted Faber
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Anantha Ramaiah (ananth)
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Ted Faber
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Anantha Ramaiah (ananth)
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Ted Faber
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Joe Touch
- Re: [tcpm] WGLC: draft-ietf-tcpm-tcpsecure-10.txt Ted Faber