Get the SAN (subjectAltName) of a site's certificate.

echo "quit" | openssl s_client -connect facebook.com:443 | openssl x509 -noout -text | grep "DNS:" | perl -pe "s/(, )?DNS:/\n/g"
Based on http://stackoverflow.com/questions/13127352/checking-alternative-names-for-a-san-ssl-cert Replace "facebook.com" with the desired hostname.
Sample Output
depth=1 /C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert High Assurance CA-3
verify error:num=20:unable to get local issuer certificate
verify return:0
DONE

*.facebook.com
facebook.com
*.fb.com
fb.com
*.fbsbx.com
*.fbcdn.net
*.xx.fbcdn.net
*.xy.fbcdn.net
*.xz.fbcdn.net
*.m.facebook.com
*.messenger.com
messenger.com

1
By: lgarron
2015-08-13 22:50:45

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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