From: Piete Brooks <Piete.Brooks@cl.cam.ac.uk>
Date: Fri, 25 Aug 95 04:11:59 PDT
To: jim@acm.org
Subject: Re: Cypherpunk Brute Squad [Re: SSL Challenge: Server problems]
In-Reply-To: <199508250059.RAA02668@mycroft.rand.org>
Message-ID: <"swan.cl.cam.:226410:950825111043"@cl.cam.ac.uk>
MIME-Version: 1.0
Content-Type: text/plain


**** Anyone participating in the SSL Challenge who has logs of their searches
**** please ensure you read "What to do if you have logs" below

** Anyone who is running a brclient earlier than 0.14 or a brloop earlier
** than 0.05 please ensure you read "current requirements"

> Live and/or learn

The purpose of this project was the latetr ...

> -- looks like the performance is a little better now that they're handing out
> bigger chunks.

That is just one of the tweaks I made ...

> The important thing is to learn something new each time so the next one goes
> more smoothly.

Indeed -- the current project is a merge of three I had planned ...

> Should be nicer with hierarchical servers and so on for the next challenge...
> DES or lobotomized DES or whatever.

Yeah .... :-)



This project arose from the "failed" rc4-40 attempt.
Personally I think it worked -- it showed that it was possible to scan a 40 
bit address space performing the kind of manipulations needed for brute force 
attacks.

The WWW interface was a pain as it required users to do something, so the norm 
was to allocate large chunks, etc.
Also collating the results was a nightmare !

So we decided that cutting the people out would be a good idea all round.
We bolted it all together, and it seemed kind of OK.
The plan was then to pass it round a wider audience to check that it ported to 
other systems and environments, and once it was shown to bsasically work, see 
how it stood up to heavy usage. Finally we could let it rip & see what it 
could do.
Unfortunately, due to various external pressures, we have ended up rolling all 
these three into one. It has made it a lot messier than I would have hoped, 
for which I apologise to you all.

rc4-40 had shown that 40bit address spaces could be scanned.
hal1 slipped through our fingers, and showed somewhat more than we had 
planned, i.e. that actual code could be broken by a *single* person (this 
sounds more impressive, but is technically easier !).
We asked for hal2 and hal3 to "check it works" and "watch it zip" repectively.
Before he left, Hal gave us hal2, so we combined the two remaining stages.

SO: this project is:
    1) to shake down the code on different systems
    2) to see how it works under real load
    3) to see how quickly a 40bit address space can be scanned.

Again I apologise to you all that (1) has been non-trivial and that (2) has 
had unpleasant effects of (1). I think next time we may be ready for (3) ...

I was going to summarise some of the lessons so far, but things are getting 
congested again, so I shall send out this PLEA to ensure recent code is used !!

current requirements
====================

PLEASE ensure that you are using a brclient of at least 0.14
("grep comment.inffo brclient" to discover what you are using)
You can updare brclient while brloop is running.
Some people are still running old versions, and this is hammering the server.

It also helps to run at least brloop 0.05 ("grep BRLOOPCOMMENT brloop").

What to do if you have logs
===========================

During the early part of the project, the server was highly congested, and I 
fear that many ACKs may have been lost :-(

If you have logs of the searches your machine(s) did, it would be useful to 
check  that all ACKs got through.

Look at the stats page http://www.brute.cl.cam.ac.uk/cgi-bin/brute?op=stats
(or something like
http://www.brute.cl.cam.ac.uk/cgi-bin/brute?op=stats&project=&proj=2977+Hal%27s
+second+challenge&substring=YourID&patt=unacknowledged
but with YourID repleaced by the ID ypou use)
and look for all the NOACKs. e.g:
	008f      NOACK 008f   1 Piete Brooks <pb@cl.cam.ac.uk>
See if there is a corresponding entry in your logs
	grep -h '2977 [0-9a-f]* 008f [0-9]* [n0-9a-f][o0-9a-f]'
and if so, ACK it
	brclient -Ltssl -a'2977 2a07 008f 1 no'

[ If your a HACKer, you can automate it, as in

	lynx -dump 'http://www.brute.cl.cam.ac.uk/cgi-bin/brute?op=stats&project=&proj
=2977+Hal%27s+second+challenge&substring=Piete.Brooks&patt=unacknowledged' |
	grep ' NOACK ' | while read a b; do
	   grep -h '2977 [0-9a-f]* '$a' [0-9]* [n0-9a-f][o0-9a-f]' ~/BR-*;
	   done | while read a; do brclient -Ltssl -a"$a"; done

  of the like ....
]