Obtain cert from self signed site
openssl s_client -showcerts -connect 75.74.58.21:443 </dev/null 2>/dev/null | sed -n '/-----BEGIN CERTIFICATE-----/,/-----END CERTIFICATE-----/p' | grep -m1 -B-1 -- '-----END CERTIFICATE-----' > cert.pem
Connect with cert
curl --cacert cert.pem https://hostname.com 