Practical documentation · Authorized use only

testssl.sh

testssl.sh provides a comprehensive TLS service configuration review. It is especially useful for owned public endpoints when run under an approved scan window, with results interpreted against current policy and verified through server configuration.

WebSSLTLSCryptographyVulnerabilityCLIBash

Start safely and get useful results

Best for

• TLS configuration review
• Certificate and protocol baseline

Not for

• Unapproved endpoint scanning
• Treating one scan as a compliance certification

Before you run anything

• Document the authorized target, time window, success criteria, data-handling rules, and a named stop contact before you begin.
• Confirm the installed version with the tool’s version or help command, then compare its documented behavior with the linked upstream project before relying on any option.

Practical workflows

Beginner

Review a local TLS service

Scenario: Validate a development reverse proxy on the local machine.

./testssl.sh --fast localhost:443

Run a reduced local check to confirm protocol and certificate behavior.

Expected use: Expect protocol, cipher, and certificate observations that need policy context.

Intermediate

Save an approved staging report

Scenario: A release gate needs TLS evidence for one owned origin.

./testssl.sh --jsonfile-pretty tls-report.json staging.example.invalid:443

Create structured evidence for the explicitly approved endpoint.

Expected use: Review changes against the organization’s TLS standard and server configuration.

Interpret results like an analyst

• A weak protocol finding may be intentionally enabled for a documented legacy dependency; validate ownership and risk.
• Certificate-chain and hostname errors should be confirmed from multiple clients where relevant.

Common mistakes and operating tips

Avoid

• Scanning without considering rate limits or WAF sensitivity.
• Calling a report a compliance attestation without policy mapping and exception review.

Operational discipline

• Treat command output as evidence, not a conclusion: retain the command, version, scope, timestamp, and a redacted result in the engagement record.
• Start with the smallest safe scope, validate expected behavior in a lab or pilot, then expand only when the authorization and monitoring plan support it.

Verify against the current upstream

Tool behavior and release syntax can change. Treat this guide as practical operating context, then verify version-specific details against the upstream project before an assessment.

Open authoritative upstream documentation