To download the certificates of the SSL secured server, use the following command.
openssl s_client -connect <secure authentication server IP and port> -showcerts < /dev/null > server.crt
The following examples show how you can download using different servers.
RED HAT CDN
openssl s_client -connect cdn.redhat.com:443 -showcerts < /dev/null > server.crt
LDAP or Active Directory
openssl s_client -connect the.ldap.server.net:636 -showcerts < /dev/null > server.crt
OAuth (Use the Authorization URL). For example, with GitHub
openssl s_client -connect github.com:443 -showcerts < /dev/null > server.crt