On 2024-07-01 10:41, Viktor Dukhovni via Exim-users wrote: > On Sun, Jun 30, 2024 at 11:32:58PM +0200, Wolfgang via Exim-users wrote: > > > I have problems connecting DANE configured hosts, when the MX has a > > correct TLSA-RR but an valid certificate (letsencrypt) with the wrong > > CN. > > This is required and expected behaviour. See: > > > With DANE-TA(2) TLSA records, the TLSA base domain (generally equal to > the MX hostname) MUST be one of the DNS SANs (or perhaps be the fallback > CN in the absence of any DNS SANs) in the certificate. Thanks for the hint to the SANs, I checked right now only the CN. The failing cert contains the right hostname as a SAN, so I really don't get it, why this connection fails. Exim complains with: "TLS session: (gnutls_handshake): Key usage violation in certificate has been detected." So I make miss a configuration option, that exim should look into the SANs of the corresponding cert, in case this is a DANE validated connection.
> > Otherwise, any MX host with a Let's Encrypt certificate could > impersonate any other such host. I don't get this: Even, when either the CN nor an additional SAN matches, I see no risk for impersonating, as the trusted public key belongs to an private key. So if someone has further hints, what I am missing in my configuration. Regards Wolfgang -- ## subscription configuration (requires account): ## https://lists.exim.org/mailman3/postorius/lists/exim-users.lists.exim.org/ ## unsubscribe (doesn't require an account): ## exim-users-unsubscr...@lists.exim.org ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
