On Mon, May 18, 2020 at 06:59:59PM +0200, Claus Assmann wrote: > I'm stuck and looking for some hints/help. I have two MTAs (let's > call them M1 and S8), both built with OpenSSL 1.1.1g. The problem > is M1 cannot establish a TLSv1.3 connection with S8. Using other > MTAs/sites/protocols/tools works just fine, e.g., M1 can send mail > to google using TLSv1.3, and S8 can send mail to M1. Replacing the > server or client with openssl s_client/s_server also works. I'll strongly second Matt's request for a PCAP file. > M1 client side: > apps_ssl_info_cb, where=10, ret=1 > apps_ssl_info_cb, SSL_connect=before SSL initialization > ssl_msg_cb, writep=1, version=0, len=5, ct=100 > ssl_msg_cb, SSLv3/TLS write client hello > ssl_msg_cb, writep=1, version=772, len=512, ct=16 > ssl_msg_cb, SSLv3/TLS write client hello > apps_ssl_info_cb, SSL_connect=SSLv3/TLS write client hello > ssl_msg_cb, writep=0, version=0, len=5, ct=100 > ssl_msg_cb, SSLv3/TLS write client hello > apps_ssl_info_cb, SSL_connect=SSLv3/TLS write client hello > ssl_msg_cb, writep=0, version=772, len=88, ct=16 > ssl_msg_cb, SSLv3/TLS read server hello > apps_ssl_info_cb, SSL_connect=SSLv3/TLS read server hello > ssl_msg_cb, writep=1, version=0, len=5, ct=100 > ssl_msg_cb, SSLv3/TLS write change cipher spec > ssl_msg_cb, writep=1, version=772, len=1, ct=14 > ssl_msg_cb, SSLv3/TLS write change cipher spec > apps_ssl_info_cb, SSL_connect=SSLv3/TLS write change cipher spec > ssl_msg_cb, writep=1, version=0, len=5, ct=100 > ssl_msg_cb, SSLv3/TLS write client hello > ssl_msg_cb, writep=1, version=772, len=512, ct=16 > ssl_msg_cb, SSLv3/TLS write client hello > apps_ssl_info_cb, SSL_connect=SSLv3/TLS write client hello > ssl_msg_cb, writep=0, version=0, len=5, ct=100 > ssl_msg_cb, SSLv3/TLS write client hello The client trace looks rather odd, why is writing the hello again after CCS? I don't recall what happens with HRR (Hello retry request) when client's initial keyshare is not usable on the server... Any unusual signature algorithm preferences in this particular client? -- Viktor.