On Thu, Sep 24, 2020 at 07:43:04AM -0700, PGNet Dev wrote: > > I'd be tempted to drop most if not all of those settings, they're not email-friendly. > > PUBLIC email non-friendly, because of still-frequent old cipher/protocol implementations? > > or, > > inherently problematic with TLS in/onr SMTP? Mostly the former. > > Also, Postfix has no knowledge of TLS 1.3 cipher suites, Postfix has > > only cipher configuration knobs only for the TLS <= 1.2 ciphers, so > > I don't know how that particular string ended up in your logs. > > a bit too postfix-y for this list, but ... > > I'm then perhaps misreading > > http://www.postfix.org/TLS_README.html > http://www.postfix.org/FORWARD_SECRECY_README.html > > In any case, the following should be with defaults. > > > Is there something in your Postfix configuration that resembles that > > particular blob? If so, it should not be there... > > yep. now removed ... That's very likely to have been the cause of the problem. That setting was not valid as a TLS <= 1.2 cipherlist. > simplifying > > /etc/pki/tls/openssl.cnf > openssl_conf = default_conf > [default_conf] > ssl_conf = ssl_sect > [ssl_sect] > system_default = system_default_sect > [system_default_sect] > Options = PrioritizeChaCha > > send/receive is successful. > > postfix logs > > Trusted TLS connection established from > internal.mx.example.com[10.0.1.17]: TLSv1.3 with > cipher TLS_AES_256_GCM_SHA384 (256/256 bits) > key-exchange X25519 server-signature ECDSA (P-384) > server-digest SHA384 client-signature ECDSA (P-384) > client-digest SHA384 So client and server both support TLS 1.3, and use AES-256-GCM by default. > changing only > > /etc/pki/tls/openssl.cnf > - Options = PrioritizeChaCha > + Options = ServerPreference,PrioritizeChaCha > > @ re-test submit to dovecot FAILs, > > postfix log > > Sep 24 05:01:44 mx postfix/submit-from-dovecot-proxy/smtpd[11261]: connect from internal.mx.example.com[10.0.1.17] > Sep 24 05:01:44 mx postfix/submit-from-dovecot-proxy/smtpd[11261]: SSL_accept error from internal.mx.example.com[10.0.1.17]: -1 > Sep 24 05:01:44 mx postfix/submit-from-dovecot-proxy/smtpd[11261]: warning: TLS library problem: error:1408F10B:SSL routines:ssl3_get_record:wrong version number:ssl/record/ssl3_record.c:331: > Sep 24 05:01:44 mx postfix/submit-from-dovecot-proxy/smtpd[11261]: lost connection after CONNECT from internal.mx.example.com[10.0.1.17] > Sep 24 05:01:44 mx postfix/submit-from-dovecot-proxy/smtpd[11261]: disconnect from internal.mx.example.com[10.0.1.17] commands=0/0 > > again, the _only_ change between the two submissions is the addition of the "ServerPreference" option to the openssl.cnf config. This looks like the protocol version is no longer TLS 1.3 as a result, and one side or the other now expects or sent the wrong protocol version. For further progress a PCAP file is needed which contains a full capture of exactly one TCP connection corresponding to this failure. You should check for any other non-default Postfix TLS settings that may have been set to poorly chosen values. > still not clear to me which piece(s) of that^ are having an issue with it. or why. Ultimately, the TLS library (OpenSSL) is failing to interoperate between client and server after this change. But whether this is a bug in OpenSSL, or a problem setting in the application is not yet clear. > for this list, my initial question is -- *IS* it openssl's "fault"? > or mine, or one of the other apps'? You need to post A PCAP file that tshark can read with a single TCP session containing the failed handshake. What are the exact OpenSSL versons on the client and server? Anything interesting in openssl.cnf on the client end? -- Viktor.
