openssl: download a certificate

openssl s_client -connect ecx.dellroad.org:443

openssl: auth via tls certificate in s_client

If you’ve gotten yourself into a corner and need to test tls authentication, you can use this.

openssl s_client -connect server.example.com -host client.example.com -servername server.client.com -key key.pem -cert cert.pem

openssl: check to see if ssl3 works

openssl s_client -connect 10.99.1.19:443 -ssl3

openssl: check to see if tls 1.2 works

openssl s_client -connect 10.99.1.19:443 -tls1_2

openssl: grab the cert

openssll s_client -connect example.com:443 2>/dev/null < /dev/null | sed -ne '/-BEGIN CERTIFICATE-/,/-END CERTIFICATE-/p' > cert.pem