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Date:      Thu, 11 Jan 2001 12:11:44 +0000
From:      Josef Karthauser <joe@tao.org.uk>
To:        itojun@iijlab.net
Cc:        freebsd-security@FreeBSD.ORG
Subject:   How does Racoon exchange packets after policy has been defined?
Message-ID:  <20010111121144.B3594@tao.org.uk>

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Hi Itojun,

I'm a bit confused as to how key exchange works between two machines?

Imagine that I've used setkey to set a policy that all traffic between
two machines should be encrypted.  Once this has been done no traffic
flows until the IPsec engine has got keys relating to this SPI AFAIU.

I don't understand how Racoon (IKE) can occur.  It can't occur in the
clear because the security policy says that only encrypted packets can
flow, and it can't occur encrypted because no keys have been installed
yet.

Is there some special handling of IKE packets in the kernel to allow
this to work?

Joe


On Thu, Jan 11, 2001 at 11:32:03AM +0900, itojun@iijlab.net wrote:
> 
> >> > Use a password generator that creates passwords with upper/lower case letters
> >> > and numbers.  This gives me 62 possible combinations.  3DES uses 192-bit keys
> >> > for a keyspace of 2^192.  So the problem is 62^x = 2^192.  Take the log of both
> >> > sides and divide to get: 32.2.  Therefor, a 33 length password should provide a
> >> > slightly greater keyspace to search than the 3DES keyspace.
> >> >
> >> > Am I doing this correctly?  Also, if neither machine is compromised, is there
> >> > any reason to change keys periodically since I am using IKE?
> 
> 	preshared keys are not directly related to IPsec key length,
> 	preshared keys are just for authenticating IKE daemon at the other end.
> 	so key length argument (above) may not be 100% right...
> 
> itojun
> 
> 
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