Get as much IP space as you ever dreamed of, was: Re: Looking to buy IPv4 addresses from class C swamp

Richard Welty rwelty at
Tue Apr 29 12:32:08 UTC 2003

On Tue, 27 May 2003 05:03:31 -0700 todd glassey <todd.glassey at> wrote:
> What I dont understand is the need to stay 1:1 routable. Most all of you
> larger ISP's could have your own private IP Space by simply running a
> NAT'd
> infrastructure. Why not do it for all your customers?

umm, because there are protocols (like IPSec) which make end-to-end
assumptions that are broken by NAT?

yes, IPSec can be gotten through NAT, in some very specific cases, but i
have a client who is 1) on ameritech DSL (/29 space allocated) and
2) requires a specifc IPSec setup to communicate with one of their vendors,
an IPSec configuration that won't pass through NAT. if Ameritech (the only
viable DSL choice in their area) NATed, they'd be SOL, unable to
communicate with their vendor.

Richard Welty                                         rwelty at
Averill Park Networking                                         518-573-7592
              Unix, Linux, IP Network Engineering, Security

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