NAT etc. (was: Spam Control Considered Harmful)

Jay R. Ashworth jra at
Mon Nov 3 19:27:54 UTC 1997

On Mon, Nov 03, 1997 at 11:27:41AM -0700, Yakov Rekhter wrote:
> > On Mon, Nov 03, 1997 at 01:49:13PM -0500, Sean M. Doran wrote:
> > > One of the ways to make it and renumbering seamless is to
> > > understand that IP addresses are subject to change over
> > > time and topological distance.
> > 
> > Wel, yes... <sigh>, but as I've noted before, that's an assumption that
> > the current design of the Internet does _not_ require.
> Quoting RFC2101 ("IPv4 Address Behavior Today") Section 4.2:
>       To summarize, since the development and deployment of DHCP and
>       PPP, and since it is expected that renumbering is likely to become
>       a common event, IP address significance has indeed been changed.
>       Spatial uniqueness should be the same, so addresses are still
>       effective locators. Temporal uniqueness is no longer assured. It
>       may be quite short, possibly shorter than a TCP connection time.

Um, the RFC notwithstanding, there are _acres_ of stacks out there that
keep track of a connection by an {IPaddr, protocol, port} tuple, and
don't expect to have to rewrite any of that during a connection.

Can anyone document a stack that _does_ deal correctly with an IP
address changing during a connection session?  Between sessions sure...
but during?

-- jra
Jay R. Ashworth                                                jra at
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