Mailing List Archive: UnNATing

UnNATing

Jul 24, 2001, 5:00 AM

Post #1 of 4 (1978 views)

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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RE: UnNATing [ In reply to ]

Filip.Sneppe at cronos

Jul 24, 2001, 5:16 AM

Post #2 of 4 (1930 views)

Permalink

Toby Chamberlain [SMTP:tjchamberlain@hotmail.com] 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

RE: UnNATing [ In reply to ]

tjchamberlain at hotmail

Jul 24, 2001, 5:59 AM

Post #3 of 4 (1923 views)

Permalink

>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

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RE: UnNATing [ In reply to ]

N.Morse at hyperknowledge

Jul 24, 2001, 6:06 AM

Post #4 of 4 (1934 views)

Permalink

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??