Re: How does Linux do RTTM?
From: John Richard Moser
Date: Sat Aug 12 2006 - 09:30:01 EST
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David Miller wrote:
> Please use netdev@xxxxxxxxxxxxxxx for discussions about the linux
> networking implementation, not linux-kernel@xxxxxxxxxxxxxxx
I'm told now that it uses Jiffies for TCP timestamps. I've had thoughts
- I figured a random timestamp with random microsecond skew would be
nice but this might expose internals of the RNG; amusingly I'm trying
not to expose internals of the RNG by exposing system time.
- Someone recommended starting at zero. This would work, really,
there's no attacks based on guessing the TCP timestamp value. This is
nice since if I want to hax0rz then I might make a connection and see
how many jiffies there are to get a feel for the system's uptime; this
tells me how long since you upgraded your kernel, so I have an arsenal
of vulns I KNOW you haven't fixed ready ;) Starting at 0 doesn't give
> Thanks a lot.
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