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RE: Bridging non-IP traffic over IPSec
I noticed that Scott G. Kelly <skelly@redcreek.com> wrote:
>> [...] Given that PPTP has been shown
>> to be very broken (by Schneier, et al), and given that ultimately,
>> putting a bunch of extra bits on already overtaxed network wires is
>> frowned upon by most realists, even m$ may have difficulty convincing
>> everyone that their way is the only way [...]
To which, Sumit A. Vakil replied:
> Actually, Schneier makes it very clear that its not PPTP, but the
> implementation of PPTP they analyzed that is broken. Check out his FAQ on
> the topic at http://www.counterpane.com/pptp-faq.html.
Please be aware that this FAQ does not go nearly far enough
in condemning PPTP. MS-PPTP is just one particularly weak
version of challenge-hashed-response authentication for
passwords (CHRAP), in which, according to the FAQ:
"Passwords are protected by hash functions
so badly that most can be easily recovered."
What the FAQ neglects to say, however, is that even a "good"
implementation of PPTP, like all similar methods based on
purely symmetric ciphers or hash functions, necessarily
exposes *lots* of user passwords to brute-force network attack.
In my view, this is completely unacceptable.
Given the *many* stronger alternatives today, with IPSEC as
merely one example, there is just no good excuse to use PPTP
or any similar CHRAP over an otherwise insecure network.
-------------------------
David P. Jablon
Integrity Sciences, Inc.
dpj@world.std.com
<http://world.std.com/~dpj/>
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