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Security Tools

Review the security posture a client sees: certificate chains and expiry, negotiated ciphers, response headers, open services and hostnames that expand your attack surface.

How these tools run · TLS checks perform a real TLS handshake with Node.js tls against port 443 and inspect the presented certificate chain; the Security Headers and Exposure Check tools issue HTTP requests from the server; Subdomain Discovery and CT Log Search query the public crt.sh Certificate Transparency service.

Tools in this category

SSL / TLS Check

Chain, expiry, protocols and cipher suites.

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Security Headers

HSTS, CSP, referrer and frame policy audit.

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Certificate Monitor

Days remaining and issuer for every SAN.

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Subdomain Discovery

Passive enumeration from CT logs and DNS data.

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Exposure Check

Internet-facing services on a host or range.

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CT Log Search

Certificates issued for a domain over time.

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Related guides

In-depth articles that cover security tools in more detail.

Security

Reading a TLS Certificate Chain Without Panicking

A certificate is just a structured document. Learn to read the fields that matter — chain order, SANs, expiry, and the trust anchor — and TLS debugging stops being intimidating.

Security

A Field Guide to HTTP Security Headers

Security headers are cheap, effective, and frequently missing. A practical tour of HSTS, CSP, referrer, and frame policies — what each does and how to audit them.

Editorial note

Maintained by the networkutils.org editorial team. Tool descriptions and methodology on this page reflect the live implementation in the NetworkUtils.org backend. Last updated September 2026.