1. Connect to specific port and show certificate detail
$ openssl s_client -showcerts -connect www.saroot.net:443
2. Show certificate expire date
$ echo | openssl s_client -connect www.saroot.net:443 2>/dev/null | openssl x509 -noout -dates
3. Certificate finger print
$ openssl s_client -connect www.saroot.net:443 < /dev/null 2>/dev/null | openssl x509 -fingerprint -noout -in /dev/stdin
