RE: IPv4 flag day

I can't imagine any case in where the ability to arbitrarily punch through your firewall (as an attacker) once I have any kind of foothold is a good feature. 

It's explicitly one reason why I highly dislike 1:many NAT, having been party to cleanup of attacks where such technique was leveraged. 

-----Original Message-----
From: William Herrin via NANOG <[email protected]> 
Sent: Thursday, June 18, 2026 5:06 AM
To: North American Network Operators Group <[email protected]>
Cc: William Herrin <[email protected]>
Subject: Re: IPv4 flag day

On Wed, Jun 17, 2026 at 10:39 AM Douglas Fischer via NANOG <[email protected]> wrote:
> NAT is cancer!
> NAT in IPv6 is spreading cancer cells to all the organs of a new, 
> healthy body.

Hi Douglas,

Hate on it all you want, 1:many NAT renders my internal network not just inaccessible from the Internet but inaddressible as well. That's a feature not a bug. It's a feature I want for some of my subnets.
When I get around to deploying IPv6 on those subnets it's a feature I will use. You don't have to like it. It's not your network.

Regards,
Bill Herrin

--
For hire. https://bill.herrin.us/resume/ _______________________________________________
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