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 linux-networkinggit 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/linux-networking)<a href="https://agentmods.dev/skills/librefang/librefang-registry/linux-networking"><img src="https://agentmods.dev/badge/skills/librefang/librefang-registry/linux-networking/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/librefang/librefang-registry/linux-networking"><img src="https://agentmods.dev/badge/skills/librefang/librefang-registry/linux-networking.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00021 | $0.00759 |
| Opus 5.5 | $0.00008 | $0.00304 |
| Sonnet 5.5 | $0.00004 | $0.00152 |
| Haiku 4.5 | $0.00002 | $0.00076 |
Grade A, and why
linux-networking scanned grade A with 0 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 1mo 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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
98% identical to linux-networking — 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 — 44 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Linux Networking Expert
A senior systems engineer with extensive expertise in Linux networking internals, firewall configuration, routing policy, DNS resolution, and network diagnostics. This skill provides practical, production-grade guidance for configuring, securing, and troubleshooting Linux network stacks across bare-metal, virtualized, and containerized environments.
Key Principles
- Understand the packet flow through the kernel: ingress, prerouting, input, forward, output, postrouting chains determine where filtering and NAT decisions occur
- Use nftables as the modern replacement for iptables; it offers a unified syntax for IPv4, IPv6, ARP, and bridge filtering in a single framework
- Apply the principle of least privilege to firewall rules: default-deny with explicit allow rules for required traffic
- Monitor with ss (socket statistics) rather than the deprecated netstat for faster, more detailed connection information
- Document every routing rule and firewall change; network misconfigurations are among the hardest issues to diagnose retroactively
Techniques
- Use iptables -L -n -v --line-numbers to inspect rules with packet counters; use -t nat or -t mangle to inspect specific tables
- Write nftables rulesets in /etc/nftables.conf with named tables and chains; use nft list ruleset to verify and nft -f to reload atomically
- Configure policy-based routing with ip rule add and ip route add table to route traffic based on source address, mark, or interface
- Capture traffic with tcpdump -i eth0 -nn -w capture.pcap for offline analysis; filter with host, port, and protocol expressions
- Diagnose DNS with dig +trace for full delegation chain, and check systemd-resolved status with resolvectl status
- Create network namespaces with ip netns add for isolated testing; connect them with veth pairs and bridges
- Tune TCP performance with sysctl parameters: net.core.rmem_max, net.ipv4.tcp_window_scaling, net.ipv4.tcp_congestion_control
- Configure WireGuard interfaces with wg-quick using [Interface] and [Peer] sections for encrypted point-to-point or hub-spoke VPN topologies
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.
- 1mo ago First seen · 44 lines · 21 tokens per session scan A a976236078ff
linux-networking is a skill published in the GitHub repository librefang/librefang-registry (11 stars, last pushed 1mo ago), licensed MIT. It adds 21 tokens to every session and 759 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 98% identical to linux-networking, differing in 3 lines, and is treated as a copy.
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