(coffee != sleep) & (!coffee == sleep)
Donald(_dot_)Smith(_at_)qwest(_dot_)com gcia
-----Original Message-----
From: opsec-bounces(_at_)ietf(_dot_)org
[mailto:opsec-bounces(_at_)ietf(_dot_)org]
On Behalf Of Fernando Gont
Sent: Monday, April 13, 2009 1:23 PM
To: Joe Touch
Cc: tcpm(_at_)ietf(_dot_)org; ietf(_at_)ietf(_dot_)org; Joe Abley;
opsec(_at_)ietf(_dot_)org;
Lars Eggert; Eddy,Wesley M. (GRC-RCN0)[Verizon]
Subject: Re: [OPSEC] [tcpm] draft-gont-tcp-security
Joe Touch wrote:
So we had tcp-secure in 2004, icmp-attacks in 2005, a claim for a
trivial attack in 2008 (Outpost24/CERT-FI), and we'll
probably continue
in this line, because we do nothing about it.
Whether we have this document or not, we will continue to
have people
who incorrectly assume that TCP is secure.
Secure is a general term. TCP was intended to address several areas of security.
The classic tenets for computer security is:
CIA -> Confidentiality, Integrity and Availability.
TCP doesn't attempt to address Confidentiality.
However it was designed to address integrity and availability so failures in
those areas should be documented and addressed in some fashion.
That's correct. But we also have people that do know it is not mean to
be secure, but that it should be resilient enough so that it's still
usable. One way or another, most stacks implement counter-measures for
SYN-floods (on which tcpm did publish something), timers on the
FIN-WAIT-2 state, port randomization (on which tsvwg is working), ICP
ISN randomization, etc.
The reason for which they did that was to improve TCP's
security/resiliency.
Would you argue in favour of predictable ISNs, predictable ports,
time-less FIN-WAIT-2 state, etc.? -- I hope you wouldn't.
It summarizes issues already raised by the WG,
I believe this statement is unfair with respect to our
document. e.g.,
has the issues described in Section 4.3, Section 9.2, or
Section 10 been
brought to tcpm before???
I didn't say that's all it does ;-) Agreed that it raises
other issues,
many of which are operational.
Many of which arise if you expect to use TCP in some other
scenario that
just two computers in a LAN. If that makes those issues
"operational", I
agree.
TCP itself is not a secure protocol, nor is it intended to be.
Again, it was intended to help ensure integrity and availability.
Yeah. But that does not mean that we should not do our
best to improve
it.
It means we should not try to give the incorrect impression that it
*can* be secured.
It can be made better that is not an incorrect impression it is a fact.
It's security/resiliency can be improved. After all, if that were not
the case, I guess you're wasting your time with TCP-AO. Or is it that
you believe the only way to improve a protocol is to throw
crypto at it?
Adding crypto improves confidentiality and integrity but is counter productive
to availability as most
crypto engines are prone to fairly low pps resource exhaustion attacks.
Interpreting every unexpected event as an attack makes
a protocol robust but also brittle; TCP is intended to
trade flexibility
for security, AFAICT, because it is agnostic about intent,
and gives the
benefit of doubt at all times.
I would prefer that instead of making this type of broad
statement, you
would argue against a particular recommendation in
draft-gont-tcp-security, and explain how it makes TCP more brittle.
Consider packet drops. That can happen due to loss, non-malicious
corruption, or jamming, e.g. In the last case, it makes
sense to blast
copies of packets in the hopes of getting something
through, but that's
NOT what we assume.
Wasn't this very behavior what lead to the Internet
congestion collapse
in the 80's, or am I missing something?
Please talk to vendors. I don't want to reproduce here
what seems to
be the consensus among vendors with respect to the current state of
affairs in terms of how up-to-date our specs are.
I talk to vendors a lot. I don't think there is a consensus on the "how
up-to-date our specs are".
I can't even get a straight answer on how they addressed the icmp-blind resets
or the tcp-blind resets from several years ago. There were several possible
mitigations with some trade offs on each of them. Yet finding out how your
favorite vendor addressed those is likely to be difficult.
Vendors misapply our protocols then complain that they
don't work. Yes,
there are operational issues, but one severe operational
issue is not
using security for some policy, financial, or operation
expense and then
complaining that nonsecure TCP is being attacked.
Again the use of a generic "secure". What do you mean by "nonsecure" here?
Joe, we're talkng about a simple web server being taken down
because of
a SYN flood, a FIN-WAIT-2 flood, or the like. Even the most stupid web
server should survive these types of attacks.
Kind regards,
--
Fernando Gont
e-mail: fernando(_at_)gont(_dot_)com(_dot_)ar || fgont(_at_)acm(_dot_)org
PGP Fingerprint: 7809 84F5 322E 45C7 F1C9 3945 96EE A9EF D076 FFF1
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