Retrieve an SSL Certificate from a Server With OpenSSL

I was setting up VMware vRealize Automation’s Active Directory connections the other day and I needed the public SSL certificate for the AD DCs to authenticate correctly. You can use OpenSSL to get that information. I used a Linux shell but this should be do-able from a Mac or with OpenSSL installed on Windows, too. If you wanted to read the SSL certificates off this blog you could issue the following command, all on one line: openssl s_client -showcerts -servername lonesysadmin.net -connect lonesysadmin.net:443 < /dev/null In this case you’ll get a whole bunch of stuff back: CONNECTED(00000003)depth=2 O = Digital Signature Trust Co., CN = DST Root CA X3verify return:1depth=1 C = US, O = Let’s Encrypt, CN = Let’s …

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