On 9/24/20 5:51 PM, Viktor Dukhovni wrote: >> 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 need to post A PCAP file that tshark can read with a single > TCP session containing the failed handshake. Been awhile since I 'de-noised' a comms dump; I'll dust off my notes, & work on getting a useful/relevant PCAP file ... > You should check for any other non-default Postfix TLS settings that > may have been set to poorly chosen values. i need to re-read, again, to figure out what those might be, and what restrictions exist. iiuc, i _should_ be able to lock this all down to specification and use of even a _single_ cipher. it's all/only 'internal' (to my org) transport after all. i can certainly live with a short list -- but with the goal to 'always' end up using TLS13 chacha20-poly1305 suite . >> 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'? > > What are the exact OpenSSL versons on the client and server? > Anything interesting in openssl.cnf on the client end? The client/server are the _same_ host. Specifically, dovecot & postfix are submission listeners on the same box -- on different ports, of course. So they both 'experience' the same openssl.cnf Version is openssl version OpenSSL 1.1.1g FIPS 21 Apr 2020 provided by distro pacakges on Fedora 32, rpm -qa | grep ssl | sort openssl-1.1.1g-1.fc32.x86_64 openssl-devel-1.1.1g-1.fc32.x86_64 openssl-libs-1.1.1g-1.fc32.x86_64
