Mailing List Archive: iptables: User

UnNATing

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tjchamberlain at hotmail

Jul 24, 2001, 5:00 AM

Post #1 of 4 (890 views)
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UnNATing

Sorry if I am terribly confused, but if I SNAT an outgoing packet from the
local LAN, is the return packet automatically DNATed back to the original
internal IP when the return packet comes in (as it would be for MASQ in
ipchains)? If so, I would assume the auto-DNAT happens pre-routing.. is this
correct?

The NAT HOWTO hints that this is the case but doesn't explicitly say it
anywhere.

Thanks
Toby

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Filip.Sneppe at cronos

Jul 24, 2001, 5:16 AM

Post #2 of 4 (854 views)
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RE: UnNATing [In reply to]

Toby Chamberlain [SMTP:tjchamberlain [at] hotmail] wrote:
>
>Sorry if I am terribly confused, but if I SNAT an outgoing packet from
>the
>local LAN, is the return packet automatically DNATed back to the
>original
>internal IP when the return packet comes in (as it would be for MASQ in

Yes, happens automatically

-Filip

tjchamberlain at hotmail

Jul 24, 2001, 5:59 AM

Post #3 of 4 (846 views)
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RE: UnNATing [In reply to]

>is the return packet automatically DNATed back to the
> >original
> >internal IP when the return packet comes in (as it would be for MASQ in
>
>Yes, happens automatically
>

And am I right in assuming that it happens _before_ any packet filtering..
so the return packet will hit the FORWARD chain and not the INPUT chain??

Thanks
Toby

_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp

N.Morse at hyperknowledge

Jul 24, 2001, 6:06 AM

Post #4 of 4 (854 views)
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RE: UnNATing [In reply to]

In this case (ie. an automatic DNAT of a return packet) yes.

>
> >is the return packet automatically DNATed back to the
> > >original
> > >internal IP when the return packet comes in (as it would
> be for MASQ in
> >
> >Yes, happens automatically
> >
>
> And am I right in assuming that it happens _before_ any
> packet filtering..
> so the return packet will hit the FORWARD chain and not the
> INPUT chain??

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