On Mar 24, 2026, at 01:47, Seo Suchan <[email protected]> wrote:
> someone on Let's encrypt forum wanted to add an extension to this to limit 
> validation to be from a specific IP.
> https://community.letsencrypt.org/t/dns-persist-01-add-ability-to-filter-request-ip/246091
> 
> I personally think it'd be better be a extension of RFC8657 than specific for 
> dns-persist-01 but still interesting proposal to discuss here.

Thanks for the pointer.

The forum poster wants source IP restrictions to replace the DNS API key that 
dns-persist-01 removes from the issuance path. The problem is that source IP 
does not work as an independent second factor. CDN and cloud IP ranges are 
shared infrastructure. If the legitimate client's requests traverse a CDN, an 
attacker with the stolen key routes through the same CDN and arrives from the 
same IP range. The constraint does not distinguish between the legitimate 
client and an attacker on the same network. For dedicated infrastructure with a 
static IP the constraint is stronger, but it also reintroduces the DNS 
maintenance dependency that dns-persist-01 was designed to remove.

This applies regardless of where the parameter lives — dns-persist-01 TXT 
record or CAA.

Shiloh

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