cert-check

Checks TLS certificate health including expiry, chain verification, TLS version, and cipher inspection for endpoints.

2|Updated Feb 16, 2026

Search Tags:#devops #security #validation #tls #certificate #expiry

Ready to run

npx skills add https://github.com/dmzoneill/skills --skill cert-check

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: cert-check
Source: https://github.com/dmzoneill/skills/tree/main/cert-check
Command: npx skills add https://github.com/dmzoneill/skills --skill cert-check

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes scripts (resource) and references (resource) components.

What problem does it solve?

This Skill helps ensure the security and reliability of your web services by automatically checking the health of TLS certificates.

Core Features & Use Cases

Expiry Monitoring: Detects certificates nearing expiration to prevent service disruptions.
Chain Verification: Confirms that the certificate chain is valid and trusted.
TLS Configuration Analysis: Inspects TLS versions and ciphers for security best practices.
HTTP Header Validation: Checks for security-related HTTP headers like HSTS.
Use Case: When you need to quickly assess the security posture of a set of web endpoints, especially before a major release or during a security audit.

Quick Start

Check the certificate health for the endpoint example.com:443, warning if it expires within 15 days.

Frequently Asked Questions about cert-check

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I check TLS certificate expiry and chain validation for a web endpoint?▼

You check TLS certificate expiry and chain validation by running an automated health assessment on the target endpoint. This verifies the certificate chain is trusted and alerts you before expiration to prevent service disruptions.

Can I inspect TLS version and cipher configuration using openssl?▼

You can inspect TLS version and cipher configuration using openssl. The health check leverages openssl alongside curl and nmap to analyze endpoints against security best practices and identify weak cryptographic configurations.

Does this TLS certificate validation require nmap and curl to be installed?▼

Comprehensive TLS certificate validation requires openssl, curl, and nmap to be installed in your environment. These tools provide the necessary functionality for chain verification, HTTP header validation, and security posture scanning.

What's the best way to assess the security posture of web endpoints before a release?▼

Assessing the security posture of web endpoints before a release requires a comprehensive scan covering TLS versions, ciphers, HTTP headers like HSTS, and Nmap port scans. This identifies vulnerabilities and misconfigurations in a single pass.

How do I validate HTTP security headers like HSTS during a TLS audit?▼

To validate HTTP security headers like HSTS during a TLS audit, execute a curl request to the endpoint and inspect the response headers. The health check includes this validation to ensure proper security configurations are present.