https://www.feistyduck.com/library/openssl%2dcookbook/online/ch-testing-with-openssl.html https://stackoverflow.com/questions/14959461/how-to-talk-to-imap-server-in-shell-via-openssl
ex:
openssl s_client -connect 10.10.10.7:993
- https://www.madboa.com/geek/openssl/
- https://wiki.openssl.org/index.php/Command_Line_Utilities
- https://www.reddit.com/r/oscp/comments/au8jy1/ncat_ssl_ctx_use_certificate_error00000000ssl/
- https://www.openssl.org/docs/manmaster/man1/s_server.html
- https://www.openssl.org/docs/manmaster/man1/s_client.html