OpenSSL • Verification & Inspection
How to View and Inspect SSL Certificate Details (Subject, Issuer, SAN)
The `openssl x509 -text -noout` command decodes all ASN.1 structures of an X.509 certificate. It reveals which Certificate Authority signed it, all covered domains, signature algorithms, and key usage constraints.
Inspect Certificate Details Command
Safe • Read-Only / File Generation
openssl x509 -in cert.pem -text -nooutCustomize:
Domain:
Cert File:
OpenSSL Flags & Options Explained
-in cert.pemInput certificate path-textDecodes and displays all certificate fields in readable format-nooutSuppresses printing of the raw base64 encoded PEM block-subjectPrints only the Subject line (CN, Organization, Country)-issuerPrints only the signing Certificate Authority (CA) identityExecution Steps & Verification
1Display complete certificate breakdown
Inspect all fields and extensions:
openssl x509 -in cert.pem -text -noout2Extract Subject Alternative Names (SANs) only
View all domains and subdomains covered by the certificate:
openssl x509 -in cert.pem -noout -ext subjectAltName3Check Issuer and Fingerprint
View issuing CA and SHA-256 fingerprint:
openssl x509 -in cert.pem -noout -issuer -fingerprint -sha256Common Security Pitfalls & Solutions
- If you get "unable to load certificate", check if the file is in binary DER format. Convert it with: `openssl x509 -inform der -in cert.cer -out cert.pem`.
Prerequisites & Environment
- Local certificate file in PEM format (.crt, .pem, or .cer).
Frequently Asked Questions About Inspect Certificate Details
Frequently Asked Questions
Frequently Asked Questions
Everything you need to know regarding specifications, syntax, and security best practices.
Look under the "X509v3 Subject Alternative Name" extension block for `DNS:domain.com, DNS:www.domain.com` entries.
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