linux-security-audit

A read-only audit tool for checking how securely a Linux computer is configured. Linux is an operating system, and security hardening means reducing unsafe settings and exposed services.

In plain words
What is it for?
Use it to inspect the kernel and boot process, filesystems, access controls, accounts, sudo, SSH, firewall, open ports, TLS, web servers, services, and installed packages.
Why use it?
It ranks security risks across the host and explains what to fix, without changing configuration by default.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/jonaslejon/linux-security-audit-plugin/linux-security-audit
Any agent
npx skills add jonaslejon/linux-security-audit-plugin --skill linux-security-audit
Clone the repo
git clone --depth 1 https://github.com/jonaslejon/linux-security-audit-plugin

Made for: Claude Code, Codex.

Per session 149 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,851 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 4 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00149 $0.05851
Opus 5 $0.00075 $0.02926
Sonnet 5 $0.00030 $0.01170
Haiku 4.5 $0.00015 $0.00585

Measured 2d ago against content hash 72a4d6a53cc5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

linux-security-audit scanned grade B with 4 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (scripts/lsa-collect.sh, scripts/lsa-trace.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Asks for rootlowPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

Establish: which host(s), is root/sudo available, is it production, and is there a baseline to

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Reads agent configuration directorieslowAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

SK="$(find -L "${CLAUDE_PLUGIN_ROOT:-$HOME/.claude}" "$HOME/.claude/plugins" "$HOME/.claude/skills" \

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Enumerates other installed skillslowAgent snooping

Other skills' SKILL.md files reveal prompts, capabilities and secrets that should be invisible to peers.

SK="$(find -L "${CLAUDE_PLUGIN_ROOT:-$HOME/.claude}" "$HOME/.claude/plugins" "$HOME/.claude/skills" \

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

`proxy_ssl_verify` left at its off default, or a `curl -k` in a cron job are all "TLS is on" and
plugins/linux-security-audit/skills/linux-security-audit/SKILL.md · 349 lines

How it starts

The opening of the file, as written. The whole thing — 349 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Linux Security Audit

Audits how hardened a Linux system is and reports what to fix, in risk order, with the exact change and its blast radius. Auditing is the default; changing the system is a separate, explicitly approved step.

What this does to the system

Designed to be run against production, so here is the precise inventory rather than a blanket warning: an overstated caution just gets ignored.

scripts/lsa-collect.sh writes nothing by default. No config is modified, no service is started, stopped or reloaded, no package is installed. Two side effects worth knowing:

  • Active checks open loopback connections: a TLS ClientHello to each listening port and an HTTP HEAD to 127.0.0.1, plus NTP peer queries. Harmless, but they appear in the audited service's own logs as connections from localhost. --passive removes them entirely.
  • --apt-update is opt-in and off by default. It is the only thing that writes anything (refreshing /var/lib/apt/lists), and it exists only because verifying that every repo is signed requires it.

Load, not risk, is the real production consideration: the whole-filesystem walks (SUID, world-writable, secrets) and package checksum verification (dpkg --verify, rpm -Va) do read I/O proportional to disk size, and on a large host the package pass alone can run for minutes. Use --quick to skip both on large or slow storage. The output header reports total elapsed time and the slowest sections, so quote those rather than guessing.

scripts/lsa-trace.sh is different and is deliberately kept separate. --live is read-only, but --unit restarts a service and --boot arm writes audit rules and needs a reboot. Every mode runs --preflight first, prints exactly what it will do, and requires --yes. It refuses outright rather than half-working when hardening blocks it.

So: run the collector on production. Run the tracer on a staging clone unless you have a specific reason not to.

Rules of engagement

Read the full file on GitHub · 349 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 349 lines · 149 tokens per session scan B 72a4d6a53cc5

Subscribe to this mod's changes

linux-security-audit is a skill published in the GitHub repository jonaslejon/linux-security-audit-plugin (13 stars, last pushed 19d ago), licensed MIT. It adds 149 tokens to every session and 5,851 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it B with 4 findings (asks for root, reads agent configuration directories, enumerates other installed skills). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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