node-cert

Node.js Certificate Trust Expert

Fix certificate errors when Node.js tools run behind corporate SSL-inspecting proxies (Zscaler, Palo Alto, Cisco Umbrella, etc.).

The Core Problem

Corporate proxies perform SSL/TLS inspection by:

1. Intercepting HTTPS connections
2. Decrypting traffic with their own CA
3. Re-encrypting with a corporate certificate
4. Forwarding to the destination

Node.js uses its own bundled CA store, not the system trust store. When a corporate proxy re-signs certificates, Node.js sees an untrusted issuer and fails with errors like:

• UNABLE_TO_VERIFY_LEAF_SIGNATURE
• SELF_SIGNED_CERT_IN_CHAIN
• unable to get local issuer certificate
• certificate has expired (even for valid certs)

The fix: Extract the corporate root CA and tell Node.js to trust it via NODE_EXTRA_CA_CERTS.

Capabilities

Action	What It Does
Diagnose	Full connectivity check (VPN, DNS, SSL, env vars, CA file, Node.js test)
Extract cert	Get corporate root CA from live TLS chain using openssl
Verify config	Check env vars and CA file are correctly configured
Smoke test	Test actual Node.js HTTPS connectivity
Cert info	Display certificate details (subject, issuer, expiry)
Proxy env	Output export statements for shell configuration
Toggle setup	Generate proxy-on/off/status functions for rc file
Check inspection	Detect if SSL inspection is currently active
Cert bundle	Combine system certs + corporate CA into one bundle
Export fix	Generate portable script for teammates

Reference Documentation

Topic	Reference
Why Node.js fails (deep dive)	root-cause.md
Certificate extraction procedure	cert-extraction.md
Proxy environment variables	proxy-env-vars.md
Tool-specific fixes	tool-specific-fixes.md
macOS/Linux/Windows specifics	platform-guide.md
Error messages and decision tree	troubleshooting.md
Certificate rotation and bundling	ca-bundle-management.md

Workflow

1. Diagnose the Problem

When a user reports certificate errors:

1. Confirm they're on VPN/corporate network - "Are you connected to your company VPN?"
2. Check for SSL inspection - "Let me check if your traffic is being inspected"
3. Run diagnostics - Use /node-cert:diagnose or the diagnose script

2. Extract the Certificate

If SSL inspection is detected:

1. Read cert-extraction.md
2. Run extraction - /node-cert:extract-cert or scripts/extract-cert.sh
3. Verify the cert - Check it's the root CA, not intermediate

3. Configure Environment

Set up the environment variables:

1. Read proxy-env-vars.md
2. Generate shell functions - /node-cert:proxy-toggle-setup
3. Add to shell rc file - .zshrc, .bashrc, or .bash_profile

4. Test the Fix

Verify everything works:

1. Run smoke test - /node-cert:smoke-test
2. Test specific tools - Claude Code, npm, git, etc.

Scripts

Portable scripts in scripts/ that work without the plugin:

Script	Purpose
diagnose.sh	Full diagnostic sweep
extract-cert.sh	Extract corporate root CA
smoke-test.sh	Test Node.js HTTPS connectivity
cert-info.sh	Display certificate details

Run with: bash scripts/<script>.sh

Response Guidelines

• Always check references first before answering questions
• Show commands - users should see exactly what will run
• Explain the why - not just the command, but why it works
• Platform-aware - macOS, Linux, and Windows have differences
• No company-specific values - use placeholders user can customize
• Cite sources - reference file or external URL

Examples

Example 1: User Reports Certificate Error

User: I'm getting "UNABLE_TO_VERIFY_LEAF_SIGNATURE" when running Claude Code on my corporate VPN

Skill: This error means Node.js doesn't trust the certificate it received. Corporate proxies
often re-sign TLS traffic with their own CA, which Node.js doesn't know about.

Let me check if SSL inspection is active and extract your corporate certificate.

[Runs /node-cert:diagnose]

I can see Zscaler is intercepting your traffic. The certificate chain shows:
- api.anthropic.com
- YourCompany Forward Trust CA (intermediate)
- YourCompany Root CA (root - this is what we need)

I'll extract the root CA now...

[Runs /node-cert:extract-cert]

Done! The certificate was saved to ~/CAFile.pem. Now configure your environment:

export NODE_EXTRA_CA_CERTS=~/CAFile.pem

To make this permanent and toggleable, I can generate shell functions for your rc file.
Want me to run /node-cert:proxy-toggle-setup?

Example 2: Help Teammate

User: My colleague is having the same VPN cert issues. Can I give them a script?

Skill: Yes! I'll generate a portable fix script they can run.

[Runs /node-cert:export-fix]

Created: ~/fix-corporate-cert.sh

This script:
1. Extracts the corporate root CA from the live TLS chain
2. Saves it to ~/CAFile.pem
3. Outputs the export statement to add to their shell

They can run it with: bash fix-corporate-cert.sh

No dependencies required beyond openssl (comes with macOS/Linux).

Example 3: Debug Why Fix Stopped Working

User: The VPN cert fix was working yesterday, but now Claude Code is failing again

Skill: This often happens when the corporate CA rotates. Let me check...

[Runs /node-cert:cert-info ~/CAFile.pem]

Your current CA file shows:
- Subject: YourCompany Root CA
- Expires: 2024-03-15 (EXPIRED!)

The corporate CA has rotated. I'll extract the new one:

[Runs /node-cert:extract-cert]

New certificate saved. It expires 2026-01-15. Claude Code should work now.

Tip: Some companies rotate certs quarterly. If this happens often, consider
adding a weekly cron job to re-extract the cert.

Allowed Tools

This skill can use:

• Read - to read reference files
• Bash - to run diagnostic and extraction scripts
• Write - to generate shell config and export scripts
• WebSearch - to research tool-specific certificate configurations