Hi Mark,

thanks a lot for your comments.

My comments below prefixed with [ML2].

Il 13/10/2026 09:42, Mark Nottingham ha scritto:
Hi Mario,

On 9 Oct 2026, at 12:11 am, Mario Loffredo <[email protected]> wrote:

NEW
If an HTTP request cannot be delivered to or accepted for EPP processing, the 
EoH server or an HTTP intermediary can return any status code applicable under 
HTTP. Examples include malformed HTTP requests, unsupported media types, 
request-size limits, rate limits, overload conditions, and gateway failures. 
Such a response represents an HTTP-layer outcome and is not an EPP response. 
EoH clients MUST be prepared to receive any HTTP status code.

An EoH server MUST NOT return a 3xx (Redirection) response to an EoH request. 
Although an HTTP intermediary might generate such a response, an EoH client 
MUST NOT follow it. The client MUST treat the response as an HTTP-layer failure 
and MUST abandon the EoH connection establishment attempt or drop the 
established EoH connection, as applicable. If the request carries an EPP 
command, the outcome of that command MUST be treated as indeterminate.

Clients MUST process unrecognized status codes according to the status-code 
class semantics defined in Section 15 of [RFC9110]. If a client does not 
receive a valid EPP response, it has not received an authoritative EPP command 
result. The client MUST process any HTTP response according to its status-code 
semantics. If the request might have reached the EPP processing layer but no 
valid EPP response is received, the outcome of the EPP command is indeterminate.
I suspect that the requirement on the server is SHOULD NOT -- in cases where 
generic HTTP infrastructure is in place (e.g., load balancers, libraries, WAFs, 
etc.) it's going to be impossible to guarantee that they won't generate a 
redirect. Remember, in HTTP a server is not just your box, it's anything that 
offers a server interface, including intermediaries.

[ML2] OK. We'll use "SHOULD NOT".

[ML] .it EPP server uses a certificate that has been issued for the server host but I guess that a 
certificate issued for the host subdomain can be used too e.g. "*.nic.example" if 
"epp.nic.example" is the server host.
Therefore, we would add the following sentence to Section 9:

The EoH client MUST verify the server identity against the host component of the EoH server URL in accordance with 
Section 4.3.4 of [RFC9110]. This verification can include wildcard matching when permitted by the applicable service 
identity verification rules. For example, a certificate containing the DNS-ID "*.nic.example" matches the 
host "epp.nic.example", but does not match "nic.example" or "test.epp.nic.example".

Moreover, given that RFC 9110 refers to RFC 6125—which is now obsolete—it might 
also be appropriate to directly reference RFC 9525 for the updated matching 
rules as follows:

EoH clients MUST verify the server identity as specified in Section 4.3.4 of 
[RFC9110], using the service identity verification procedures defined in 
[RFC9525].

Does it work for you (including the reference to RFC9525) or do you recommend 
using a dedicated certificate for the server host ?
That's up to you and the security reviewers :)

[ML] I suspected as much, but I didn't know—and still don't—whether requesting a dedicated certificate for the server host is an unnecessary security measure. :-(

We'll discuss what is most apropriate and applicable.


Thank you very much for the comprehensive review of this document.

Cheers,

Mario

Cheers,

--
Mark Nottingham   https://mnot.net/

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--
Dott. Mario Loffredo
Senior Technologist
Technological Unit “Digital Innovation”
Institute of Informatics and Telematics (IIT)
National Research Council (CNR)
Address: Via G. Moruzzi 1, I-56124 PISA, Italy
Phone: +39.0503153497
Web: http://www.iit.cnr.it/mario.loffredo

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