Openssl view website ssl certificate dns entries

Before going live with a new domain or after updating a cert, I always verify the SAN entries cover everything I need. With SNI, a cert might be valid for one subdomain but not another, and this command tells you exactly what domains the cert covers without needing a browser.

Watch Explanation on YouTube

how to view website ssl certificate dns entires using openssl

Link URL : https://youtu.be/HF5iLlQ_hA8

• split DNS entries using new line

$ echo |openssl s_client -connect google.com:443 2>/dev/null | openssl x509 -noout -text | grep DNS:| sed "s/,/\\`echo -e '\n\r'`/g"

• split DNS entries using tr

$ echo |openssl s_client -connect google.com:443 2>/dev/null | openssl x509 -noout -text | grep DNS: | tr ',' '\012'