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Re: NAT and IPSEC INCOMPATIBLE???





>>> Makoto Kubota <kubota@flab.fujitsu.co.jp> 06/09/99 05:57PM >>>
> > Looking at rfc1631 (NAT) and rfc2401 (IPSEC Overview) I have not yet
> > discovered a reason for conflict in using the two protocols together.  Just
> > trying to understand if it is possible.....or if a IPSEC and NAT are just
> > not made to function together.  Specifics of the reason this will or won't
> > work would be VERY much appreciated.
> 
> Yep, NAT breaks IPSEC.
> 
> NAT breaks any protocol which protects IP addresses from modification.
> AH's checksum includes these header fields, so that's one thing which
> breaks.

>>>Can I have additional question about this?

>>>So, if we do NAT before IPSEC, can I usr NAT & IPSec together?
>>>For example,
>>>  Home Office ---[NAT]---[IPSec]--->Internet...
>>>  Home Office <--[NAT]<--[IPSec]<---Internet...

>>> Thanks in advance.

Yes NAT breaks IPSec if NAT is between the tunnel (IPSec) points.
But, NAT can be behind the IPSec. 

umesh


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