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Re: application layer cross checking



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nuqneH,

The API should make things easier to control: you can tell your application
to, say, "allow reusable passwords if your link is protected with reasonable
crypto" or something - instead of configuring trusted ip address range and 
configuring policy for those addresses.

Afair there was a feature like that in cisco pix ;)


Michael Thomas <mat@cisco.com> said :

 >  > Even in your own example, note that IPsec works almost
 >  > entirely in terms of IP addresses, and the identity you're claiming it
 >  > should verify is based on a host *name*.  Not the same thing at all,
 >  > and the mapping between them is non-trivial.
 > 
 >    Well, explicit coupling of identity to IP
 >    addresses isn't exactly without its own set
 >    of problems (cf HIP, multihoming, mobility,
 >    etc). But I don't think we even need to raise
 >    _that_ spectre: if you're using a wildcarded
 >    rule on the incoming IP address for a
 >    particular destination port that it is 
 >    required to authenticate into a particular
 >    realm before it passes that access check, 
 >    being able check which credentials were
 >    *actually* passed to create the SA is nothing
 >    different than allowing recvfrom() to pass
 >    the incoming dst IP address as a means of identity.
 >    The stack, after all, doesn't care *what* the
 >    credentials name, it just wants to know whether
 >    to permit the traffic based upon the rule. 
 > 
 >  > What IPsec perhaps *should* have an API for, is for asking "how sure are
 >  > you that packets claiming to be from 10.20.30.40 are really from him?"
 >  > (or, perhaps better, to say "I'm opening a connection to 10.20.30.40,
 >  > please give me only packets that you are sure came from him").  It will
 >  > still be necessary, in general, for an application to do its own thinking
 >  > about what that assurance implies.
 > 
 >    I don't think this entirely disimilar to what
 >    I'm saying, though I don't think the IP address
 >    coupling is necessary to do what I'm thinking
 >    of. What I'm extremely skeptical of is having 
 >    each application re-create IKE and its kin.
 >    Ugh. You might as well just chuck IPsec
 >    altogether and use TLS. And chuck transport
 >    mode while you're at it.

                                      _     _  _  _  _      _  _
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