Re: forged tsecr giving -ve numbers in rtt calculation causing retran

From: Mike Silbersack (silby_at_silby.com)
Date: 01/19/04

  • Next message: Emil Filipov: "Re: PPPOE server with pppoed and mppe" 
    Date: Mon, 19 Jan 2004 01:21:01 -0600 (CST)
To: rw@codeburst.co.uk

    On Fri, 16 Jan 2004, Richard Wendland wrote:

    > I'd hazard a guess that you are seeing zero, not forged, TSECRs.
    > Windows sets TSECR zero on SYN-ACK when it does a passive open. This is
    > established Windows behaviour for several years, and there is a reading
    > of RFC1323 that might justify this.

    Hm, wasn't this accounted for in rev 1.174 / 1.107.2.31? From Matt's
    commit log: 

    ---
...
FreeBSD sends a
timestamp with the SYN, W2K returns a timestamp of 0 in the SYN+ACK
causing FreeBSD to calculate an insane SRTT and RTT, resulting in
a maximal retransmit timeout (60 seconds).
...
This commit works around the W2K bug.
---
Of course, that doesn't account for other non-zero strange values.  I
guess the timestamp code needs a lot of work. :(
Mike "Silby" Silbersack
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  • Next message: Emil Filipov: "Re: PPPOE server with pppoed and mppe"