Does ASA5510 check xlate table first when coming from inside?

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Sep 9th, 2009
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Cisco document says by default traffic from higher level interface to lower level interface is always allowed. However it seems for traffic going from higher interface to lower interface, ASA always checks xlate table first. So there should always be some type of NAT (pool or static) or PAT configured from higher interface to lower interface.

Is it correct?


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Collin Clark Wed, 09/09/2009 - 08:02
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Yes that is correct. Here's an example NAT from 'outside' to 'inside'

static (inside,outside) netmask

Hope that helps.

m.reay Wed, 09/09/2009 - 08:30
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You don't always need to nat the source - you can also use nat bypass or nat exemption, but this still has to be configured.

There is also an option to negate the use of NAT totally - the no nat-control command, however I recommend you fully understand this command before you use it.

gwhuang5398 Wed, 09/09/2009 - 18:35
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Thanks all. I'm clear now. I just didn't find it clearly specified in any Cisco documentations.

I've never tried "no nat-control".


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