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Re: order/nesting of IPsec headers (transport mode)



Aug 22, 97 11:45 pm
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Karen, I think any one of the other combinations should be 
mandated ONLY if there's a genuine application need for it 
out there in the market.

My preference is to let the vendors have the flexibility to
choose what combinations to offer their customers. Forbidding
a combination would be a shame if a customer were to ask for
a specific combination and the vendor were willing to provide it.
I'm assuming interoperability wouldn't be an issue.

- Ly

> 
> Folks,
> 
> Recent email has raised the question of what order/nesting of IPsec
> headers should be supported in transport mode.  In general, we've been
> assuming that ONLY the combinations of IPsec headers listed as 1-3 below
> should occur in transport mode.  ("above" = higher in the protocol
> stack, "below" = lower in the protocol stack.  So, for example, TCP is
> "above" IP):
> 
> 	1. AH only
> 	2. ESP only
> 	3. ESP above AH (i.e., in the outbound direction, do ESP processing,
>                          then do AH processing)
> 
> What is the sense of this community with regard to other combinations,
> e.g.,:
> 
> 	4. AH above ESP (i.e., authenticate first, then encrypt)
> 	5. AH above AH 
> 	6. ESP above ESP
> 	7. AH above AH above ESP
> 	8. AH above ESP above AH
> 	9. etc.
> 
> Should support for any of these be mandated? allowed? forbidden?
> 
> Thank you,
> Karen
> 
> 





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