Messages in this thread |  | | Subject | test SYN cookies (was Re: SYN cookies security bugfix?) | From | Ed L Cashin <> | Date | 08 Nov 2001 17:00:30 -0500 |
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Alan Cox <alan@lxorguk.ukuu.org.uk> writes:
> > I received a forwarded message from SuSE regarding a security vulnerability > > with respect to randomization of the ISN for SYN cookies - or something to > > that effect. I have not been able to find the patch which addresses this > > problem; if anyone can point me towards it, I would be appreciative. > > Its fixed in 2.2.20, you can grab the 2.2 patch from there
What is a good way to test SYN cookies? I can induce a three-second delay (on victim host V) before new TCP connections are accepted by sending a burst of 2000 SYN packets (from attacker A), where V is running a 2.2.14 or 2.2.17 kernel. During the three seconds ICMP echo requests from A to V are being answered.
Turning on SYN cookies after /proc is mounted does not affect the three-second pause, though, so I figure that either the pause is not on account of a full half-open connection queue or SYN cookies are not working.
-- --Ed Cashin PGP public key: ecashin@terry.uga.edu http://www.terry.uga.edu/~ecashin/pgp/
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