My Fritz!Box 6590 using current Fritz!OS 7.12 cannot use my mail server to send out push service notifications. The problem is, that my mail server uses ECDSA certificates. I see in the TLS client hello message from the Fritz!Box that only RSA certificates are supported, neither DSA nor ECDSA certificates are accepted by Fritz!Box. So the mailserver is correctly rejecting the TLS handshake with “no shared cipher”.
postfix/smtpd[22491]: SSL_accept error from unknown[xxx.xxx.xxx.xxx]: -1
postfix/smtpd[22491]: warning: TLS library problem: error:1417A0C1:SSL routines:tls_post_process_client_hello:no shared cipher:ssl/statem/statem_srvr.c:2259:
postfix/smtpd[22491]: lost connection after STARTTLS from unknown[xxx.xxx.xxx.xxx]
Is there any way to enable support for DSA certificates in the Fritz!Box? I mean actually there aren't that uncommon, it's a standard type of TLS certificate.
Is there any reason why Fritz!Box shouldn't support this type of certificates?