Server/Client

TLS 1.3 Handshake (CC) Skisope999/commons.wikimedia.org

Client

# certificate
echo -n | openssl s_client -connect www.google.de:443

# scripted
cert-info www.google.de

Server

openssl req -x509 -newkey rsa:4096 -keyout key.pem -nodes -subj '/CN=localhost' -days 365 -out server.pem

# serve on port 4433
openssl s_server -cert server.pem -key key.pem -www

SSL Labs

https://www.ssllabs.com/ssltest/analyze.html