s_client
Pull x509 certificate
HOST=myhost
openssl s_client -connect $HOST:443 -servername $HOST </dev/null 2>/dev/null \
| openssl x509 -noout -text
Pull x509 certificate summary
HOST=myhost
openssl s_client -connect $HOST:443 -servername $HOST </dev/null 2>/dev/null \
| openssl x509 -noout -subject -issuer -dates -startdate -enddate
Verify TLS communication
openssl s_client -connect host:port
x509
Decode certificate from STDIN
echo "...base64encoded..." | base64 -d | openssl x509 -text -noout
Decode certificate from file
openssl x509 -in server.crt -text -noout
Verify
Display certificate chain
openssl verify -CAfile server.crt -show_chain client.crt