Tls Handshake Debugging
Diagnose a failing TLS connection: \"SSL handshake failed\", \"tlsv1 alert\", \"unable to get local issuer certificate\", \"works in the browser but not curl\", \"certificate required\" on mTLS. Establish TCP reachability, then run openssl s_client -connect host:443 -servername host -showcerts, because a missing SNI returns the wrong certificate. Read in order: certificate served, whether the chain includes the intermediate (browsers fetch it via AIA, curl and Java do not), hostname against SAN not CN, validity dates and client clock, protocol and cipher overlap, ALPN, and for mTLS the CertificateRequest and CA list. Separate server faults from client trust with --resolve from a clean client; capture the alert first. Use for any handshake failure. Not for an internal CA that clients do not trust yet (private-ca-trust-distribution), issuance and renewal (certificate-automation), allowed protocols (host-hardening) or app code (debugging).
Security AStatic scan found no risk patternsHow grading works ›
From the source SKILL.md
This skill is done when you can state which side failed and at which step (reachability, certificate served, chain, name, validity, protocol or cipher overlap, client certificate), with the alert text or verify code as evidence, and a clean client now completes the handshake against the corrected endpoint.
What this skill does
Tls Handshake Debugging is a community-contributed Claude Code skill in the network-security sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/tls-handshake-debugging/ and loads when your prompt matches the skill's trigger.
Who uses this skill
The Tls Handshake Debugging Claude Code skill is built for security engineers, penetration testers, DevSecOps practitioners, and development teams hardening codebases and infrastructure. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 213,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).
How to install
Free
Manual install (2 steps)
mkdir -p ~/.claude/skills/tls-handshake-debugging
curl -L https://claudskills.com/skills/tls-handshake-debugging/SKILL.md \
-o ~/.claude/skills/tls-handshake-debugging/SKILL.md
Or just download SKILL.md directly and drop it into ~/.claude/skills/tls-handshake-debugging/. Claude Code auto-discovers it on next session.
Skills live at ~/.claude/skills/tls-handshake-debugging/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\tls-handshake-debugging\SKILL.md on Windows. See the full install guide for step-by-step instructions.
Telegram
📱 Install from your phone or desktop Telegram
Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →
Pro
One-click install via the desktop app
The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.
Pro
For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.
Frequently asked questions
How do I install the Tls Handshake Debugging Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy
SKILL.md from the source repository to
~/.claude/skills/tls-handshake-debugging/SKILL.md and restart Claude Code. Both flows are detailed at
claudskills.com/install/.
What does the Tls Handshake Debugging skill do?
Diagnose a failing TLS connection: \"SSL handshake failed\", \"tlsv1 alert\", \"unable to get local issuer certificate\", \"works in the browser but not curl\", \"certificate required\" on mTLS. Establish TCP reachability, then run openssl s_client -connect host:443 -servername host -showcerts, because a missing SNI returns the wrong certificate. Read in order: certificate served, whether the chain includes the intermediate (browsers fetch it via AIA, curl and Java do not), hostname against SAN not CN, validity dates and client clock, protocol and cipher overlap, ALPN, and for mTLS the CertificateRequest and CA list. Separate server faults from client trust with --resolve from a clean client; capture the alert first. Use for any handshake failure. Not for an internal CA that clients do not trust yet (private-ca-trust-distribution), issuance and renewal (certificate-automation), allowed protocols (host-hardening) or app code (debugging).
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the Tls Handshake Debugging skill?
Use Tls Handshake Debugging when your Claude Code task falls under the Security category — specifically in the network security area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Tls Handshake Debugging" or describe the task and let Claude pick). Browse related skills at
/category/security/.
What is a Claude Code skill and how does the Tls Handshake Debugging skill fit in?
A Claude Code skill is a
SKILL.md file that lives under
~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Tls Handshake Debugging is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at
/learn/what-is-a-claude-skill/.
Attribution & license
Cite this skill
If you reference this skill in a blog post, paper, or documentation, you can cite it as:
APA
greenblacked. (2026). Tls Handshake Debugging [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/tls-handshake-debugging/
BibTeX
@misc{tls-handshake-debugging-2026,
author = {greenblacked},
title = {Tls Handshake Debugging [Claude Code skill]},
year = {2026},
publisher = {ClaudSkills},
url = {https://claudskills.com/skills/tls-handshake-debugging/}
}Embed this skill
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Security scan
Grade A · scanned 2026-11-01 — free static scan against the OWASP Agentic Skills Top 10.
No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›
- ✓ Prompt injection
- ✓ Data exfiltration
- ✓ Supply chain
- ✓ Reverse shell
- ✓ Credentials
- ✓ Execution
- ✓ Filesystem
- ✓ Persistence
- ✓ Obfuscation
- ✓ Network
Show this grade on your repo (click to copy):
[](https://claudskills.com/skills/tls-handshake-debugging/#security)
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