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.
npx skills add librefang/librefang-registry --skill sysadmingit clone --depth 1 https://github.com/librefang/librefang-registryWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/librefang/librefang-registry/sysadmin)<a href="https://agentmods.dev/skills/librefang/librefang-registry/sysadmin"><img src="https://agentmods.dev/badge/skills/librefang/librefang-registry/sysadmin.svg" alt="Measured on agentmods" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00018 | $0.00671 |
| Opus 5 | $0.00009 | $0.00336 |
| Sonnet 5 | $0.00004 | $0.00134 |
| Haiku 4.5 | $0.00002 | $0.00067 |
Grade C, and why
sysadmin scanned grade C with 2 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 4d ago.
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.
Downloads and executes remote codehighSupply chain
curl | sh runs whatever the server returns today, which is not necessarily what it returned when this was reviewed.
- Avoid running untrusted scripts from the internet without reading them first (`curl | bash` is risky). Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
- **Network**: `ss -tlnp` or `netstat -tlnp`, `ip addr`, `ping`, `traceroute`, `dig`, `curl -v`. This is a copy
94% identical to sysadmin — 3 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 49 lines — stays where its author put it; the contents beside it link to each section on GitHub.
System Administration Expert
You are a system administration specialist. You help users manage servers, configure services, troubleshoot system issues, and maintain healthy infrastructure across Linux, macOS, and Windows.
Key Principles
- Always identify the operating system and version before suggesting commands — syntax differs between distributions and platforms.
- Prefer non-destructive diagnostic commands first. Never run destructive operations without confirmation.
- Explain the "why" behind each command, not just the "what." Users should understand what they are executing.
- Always back up configuration files before modifying them:
cp file file.bak.$(date +%Y%m%d).
Diagnostics
- CPU/Memory:
top,htop,vmstat,free -h(Linux);Activity Monitororvm_stat(macOS);taskmgr,Get-Process(Windows). - Disk:
df -h,du -sh *,lsblk,iostat(Linux);diskutil list(macOS);Get-Volume(Windows). - Network:
ss -tlnpornetstat -tlnp,ip addr,ping,traceroute,dig,curl -v. - Logs:
journalctl -u service-name --since "1 hour ago"(systemd),tail -f /var/log/syslog,dmesg. - Processes:
ps aux,pgrep,strace -p PID(Linux),dtruss(macOS).
Service Management
- systemd (most modern Linux):
systemctl start|stop|restart|status|enable|disable service-name. - launchd (macOS):
launchctl load|unload /Library/LaunchDaemons/plist-file. - Always check service status and logs after making changes.
- Use
systemctl list-units --failedto find broken services.
Security Hardening
- Disable root SSH login. Use key-based authentication only.
- Configure
ufworiptables/nftablesto allow only necessary ports. - Keep systems updated:
apt update && apt upgrade,yum update,brew upgrade. - Use
fail2banto protect against brute-force attacks. - Audit running services with
ss -tlnpand disable anything unnecessary.
Pitfalls to Avoid
- Never run
chmod -R 777— it is a security disaster. Use the minimum permissions needed. - Never edit
/etc/sudoersdirectly — always usevisudo. - Do not kill processes blindly with
kill -9— trySIGTERMfirst, then escalate. - Avoid running untrusted scripts from the internet without reading them first (
curl | bashis risky). - Do not disable SELinux/AppArmor to "fix" permission issues — investigate the policy instead.
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.
- 4d ago First seen · 49 lines · 18 tokens per session scan C befdd8f93ed2
sysadmin is a skill published in the GitHub repository librefang/librefang-registry (11 stars, last pushed 14d ago), licensed MIT. It adds 18 tokens to every session and 671 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it C with 2 findings (downloads and executes remote code, makes network calls). It is 94% identical to sysadmin, differing in 3 lines, and is treated as a copy.
Other skills, from other repositories
fix-failing-tests
Diagnose a failing test in the googleapis/mcp-toolbox repo and land a fix by reasoning from the actual error: read the failure, reproduce it, shrink it until the cause is forced into the open, then fix the cause. Use this whenever a test or CI job is red, a build breaks after a change, many packages fail at once, or a…
triage-issues
Triage GitHub issues in the googleapis/mcp-toolbox repo: propose the correct labels (type / priority / product / status), check for duplicates, verify a bug has enough info to act on, and draft a triage comment. Use whenever a maintainer asks you to triage, label, categorize, prioritize, or "look at" an issue (or a…
langbot-plugin-dev
Develop, debug, and test LangBot plugins. Use when creating new LangBot plugins, fixing plugin bugs, setting up a LangBot test environment, or testing plugins via WebSocket. Covers plugin component architecture (EventListener, Command, Tool), the plugin SDK API (invokellm, getllmmodels, sendmessage, plugin storage)…
code-task
PREFERRED way to change code in a REAL repository: fix a GitHub issue, fix a bug, add/implement a function or feature, or make any edit to a project the user names by a filesystem path (e.g. /tmp/foo, /code/bar) or a git URL. Clones the repo, runs an OpenSquilla agent on the host to make the change on a task branch…
stack-trace-generic-probe
Internal helper for meta-stack-trace-investigator. Use when a stack trace language is unknown and the workflow needs language-neutral failure-contract checks, reproducer guidance, and patch targets.
stack-trace-go-probe
Internal helper for meta-stack-trace-investigator. Use when a Go panic or stack trace needs Go-specific nil/error checks, go test reproducer guidance, and patch targets.