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When using curl , you may need to download or handle certificates for two primary reasons: to for local inspection or to download a Certificate Authority (CA) bundle so curl can verify secure connections. 1. How to Download a Website’s SSL Certificate
: Once downloaded, tell curl to use this specific file for verification: curl --cacert cacert.pem https://secure-site.com . 3. Quick Reference for curl Certificate Flags curl download certificate
: This command dumps the peer certificate(s) into the cacert.pem file, including the BEGIN CERTIFICATE and END CERTIFICATE markers. Using OpenSSL (Standard Method) When using curl , you may need to
: echo | openssl s_client -servername google.com -connect google.com:443 2>/dev/null | openssl x509 -inform pem -noout -text > website_cert.txt 2. Downloading the CA Certificate Bundle
If your version of curl doesn't support the certs variable, the standard "Swiss army knife" approach uses openssl :
: Use openssl s_client -showcerts -connect example.com:443 to see the entire certificate chain. 2. Downloading the CA Certificate Bundle