Guide · Agent skill
How to use the Linux Networking Expert agent skill
Updated · written with AI from the project's own documentation and checked against our catalogue data
The Linux Networking Expert is an agent skill: a SKILL.md file of expert guidance that an AI agent such as Claude loads when your request matches its topic. Once installed, the agent answers questions about iptables and nftables firewalls, policy routing, DNS resolution, tcpdump packet capture, WireGuard VPNs and TCP tuning, following cautious practices like default-deny firewalls. This guide shows you how to install the skill, how to phrase requests so it activates, and what to check before applying anything to a real machine.
Linux Networking ExpertRightNow-AI/openfang · Apache-2.0 Download the skill Quick start
- 1Download the skill. Download the linux-networking ZIP from this page. It contains SKILL.md.
- 2Unzip it into the right folder. Extract it into ~/.claude/skills/ for personal use, or into .claude/skills/ in a project. Alternatively, upload it under Settings → Capabilities → Skills in the Claude apps.
- 3Confirm your Linux tools. Check that iptables, nftables, iproute2 and tcpdump are available, plus wg-quick if you plan to set up a VPN.
- 4Describe your problem plainly. Ask in natural language that mentions firewalls, routing, DNS, packet capture or WireGuard, and include your distribution and interface names.
- 5Paste current state. Share the output of your current rules or routes so the agent can reason about what is actually configured.
- 6Review before applying. Read every suggested rule, confirm you have console access or a rollback, and test in a namespace or non-critical host first.
What the linux-networking skill makes the agent do
The skill gives the agent the working knowledge of a senior Linux network engineer. It covers packet flow through the kernel (ingress, prerouting, input, forward, output and postrouting chains), nftables as the modern alternative to iptables, policy-based routing with ip rule and ip route, DNS diagnosis with dig and resolvectl, and network namespaces for isolated testing.
It is written as guidance and reference. It does not run commands or scripts on your system, and it does not use the network. The agent explains what to run and why, and you decide what to execute.
- Firewall rules with iptables and nftables, including port forwarding with DNAT
- Policy routing by source address, mark or interface
- DNS troubleshooting, including split DNS with systemd-resolved
- Packet capture with tcpdump and MTU discovery with ping
- WireGuard VPN setup with wg-quick and TCP performance tuning with sysctl
How to install the linux-networking skill
Download the ZIP file for the skill from this page. The skill is distributed as a ZIP containing SKILL.md. Unzip it into one of these locations:
For a personal setup available across projects, unzip it into ~/.claude/skills/. For a single project, unzip it into the .claude/skills/ folder inside that project. If you use the Claude apps instead, upload the skill under Settings → Capabilities → Skills.
- Personal: ~/.claude/skills/
- Project only: .claude/skills/ inside your project folder
- Claude apps: Settings → Capabilities → Skills, then upload
How to trigger the skill with natural requests
You do not need a special command. Describe the problem in plain language that mentions the topic, such as firewall rules, routing, DNS or WireGuard. The agent matches the request to the skill's description: Linux networking expert for iptables, nftables, routing, DNS, and network troubleshooting.
Include the details that matter: the Linux distribution, whether you use iptables or nftables already, the interface names, and what is failing. Specific requests get more useful answers than general ones.
- Good: "My nftables ruleset blocks outgoing DNS on eth0. How do I check which rule is dropping it?"
- Good: "Set up a WireGuard hub-spoke VPN with three peers using wg-quick."
- Weak: "Help with my network."
Examples of useful requests
The skill works best on concrete, bounded tasks. The following kinds of requests fall within its scope, based on the patterns it describes.
Ask for an audit or explanation before asking for changes. A good first request is to have the agent review your current rules and point out risks, then decide which changes to make yourself.
- Show me how to inspect iptables rules with packet counters and line numbers.
- Write a port forwarding rule that sends external port 8080 to an internal host, with the matching FORWARD rule.
- Find the path MTU to a host using ping with do-not-fragment and varying sizes.
- Explain why ping works but my application cannot resolve names, and how to check DNS with dig +trace.
- Create a network namespace with a veth pair bridged to the host for isolated testing.
- Capture traffic on eth0 to a pcap file and filter it to one port.
iptables -L -n -v --line-numbersWhat you need before using it
The skill assumes a Linux system and the networking tools it references. Check that these are available. You need command-line and kernel-level familiarity to act on the advice, because the output is written for that audience.
For VPN work, you also need the WireGuard tools, specifically wg-quick.
- Linux with iptables, nftables and iproute2
- tcpdump for packet capture
- systemd-resolved, where it applies to your DNS setup
- WireGuard tools (wg-quick) if you are setting up a VPN
Safety notes before you apply any change
Networking mistakes can cut off your own access. The skill warns against flushing iptables rules on a remote machine without a scheduled rule restore or out-of-band console access. Keep that warning in mind for any firewall work over SSH.
The advice is generic. It does not know your topology, your existing rules or your provider's setup. Review every rule before applying it to production, and test on a non-critical machine or in a network namespace first. Also avoid mixing iptables and nftables on the same system without understanding how iptables-nft translates rules into nftables, since this can cause conflicts.
- Do not flush remote firewalls without a rollback path or console access
- Review generated rules before applying them to production
- Test in a network namespace or on a non-critical host first
- Do not assume DNS works because ping succeeds; ping can use cached results or /etc/hosts
- Avoid overly aggressive TCP keepalive or timeout values on NAT gateways
Tips for getting better results
Give the agent your current state, not just the goal. Paste the output of iptables -L -n -v --line-numbers or nft list ruleset, and say which interface and service are involved. The skill's advice on packet flow and chain order is far more precise when it can see your rules.
Ask for reasons along with commands. Because the skill emphasises documenting every routing rule and firewall change, ask the agent to explain each change so you can record it.
- Paste current rule output so the agent can reason about real state
- Name the interface, distribution and service involved
- Ask for a rollback command alongside every change
- Verify with nft list ruleset or ss rather than trusting a single test
What people use it for
- Auditing a server's iptables rules and finding overly permissive entries
- Setting up a DNAT port forward with the matching FORWARD rule
- Diagnosing why an application cannot resolve names while ping still works
- Finding the path MTU to fix fragmentation on a VPN link
- Building an isolated network namespace to test firewall rules before production
Frequently asked questions
How do I install the linux-networking agent skill?
Download the ZIP from this page and unzip it into ~/.claude/skills/ for personal use, or into .claude/skills/ inside a project. In the Claude apps, you can instead upload it under Settings → Capabilities → Skills.
Is the linux-networking skill free?
The skill is licensed under Apache-2.0, as listed for the source repository. Check the licence file in the repository for the full terms before redistributing it.
What does the linux-networking skill require?
It requires a Linux system with iptables, nftables, iproute2, tcpdump and systemd-resolved where applicable. For WireGuard VPNs you also need the wg-quick tools. It does not run scripts and does not use the network.
Can the skill change my firewall automatically?
No. The skill is written as guidance and reference, not as automated tools. It suggests commands and rules, and you decide what to run on your system.
Does this skill work on Windows or macOS?
No. The skill covers Linux networking only and does not cover Windows or macOS networking.
Should I use iptables or nftables?
The skill recommends nftables as the modern replacement for iptables, since it offers one syntax for IPv4, IPv6, ARP and bridge filtering. Avoid mixing the two on the same system without understanding how iptables-nft translates rules.
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Our verdict
Use this skill if you administer Linux firewalls, routing, DNS or WireGuard and want a knowledgeable assistant that explains its reasoning. Pick something else if you have no Linux administration background, or if you need a tool that applies and verifies changes on Windows or macOS. Never apply its generic advice to a production firewall without review and a rollback plan.
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