configuring-firewalls

configuring-firewalls is a skill for Claude Code from ancoleman/ai-design-components. It costs 67 tokens per session (3,484 once invoked), scanned A, original, MIT.

Instructions for setting up firewalls on servers, cloud platforms, and containers. A firewall controls which network connections are allowed or blocked.

In plain words
What is it for?
Use it when configuring iptables, nftables, UFW, AWS security groups, network access controls, or Kubernetes network policies for servers, databases, web services, and segmented networks.
Why use it?
It helps reduce accidental exposure of services and avoids common configuration mistakes, including locking yourself out of a server.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the security-skills plugin — 7 skills shipped together

Good fit Use it when configuring iptables, nftables, UFW, AWS security groups, network access controls, or Kubernetes network policies for servers, databases, web services, and segmented networks.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ancoleman/ai-design-components/configuring-firewalls
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.

Any agent
npx skills add ancoleman/ai-design-components --skill configuring-firewalls
Clone the repo
git clone --depth 1 https://github.com/ancoleman/ai-design-components

Made for: Claude Code.

Or install security-skills, the plugin that ships this one along with the rest of its 7 skills.

Wrote 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.

agentmods badge for configuring-firewalls

README.md
[![agentmods](https://agentmods.dev/badge/skills/ancoleman/ai-design-components/configuring-firewalls.svg)](https://agentmods.dev/skills/ancoleman/ai-design-components/configuring-firewalls)
Your own site
<a href="https://agentmods.dev/skills/ancoleman/ai-design-components/configuring-firewalls"><img src="https://agentmods.dev/badge/skills/ancoleman/ai-design-components/configuring-firewalls.svg" alt="Measured on agentmods" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,484 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00067 $0.03484
Opus 5 $0.00034 $0.01742
Sonnet 5 $0.00013 $0.00697
Haiku 4.5 $0.00007 $0.00348

Measured 9d ago against content hash 9f6852203168, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

configuring-firewalls scanned grade A with 1 finding 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 9d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (examples/ufw/basic-web-server.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.

sudo ufw default deny incoming

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

skills/configuring-firewalls/SKILL.md · 490 lines

How it starts

The opening of the file, as written. The whole thing — 490 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Configuring Firewalls

Purpose

Guide engineers through configuring firewalls across host-based (iptables, nftables, UFW), cloud-based (AWS Security Groups, NACLs), and container-based (Kubernetes NetworkPolicies) environments with practical rule examples and safety patterns to prevent lockouts and security misconfigurations.

When to Use This Skill

Trigger Phrases:

  • "Configure firewall for [server/service]"
  • "Set up security groups for [AWS resource]"
  • "Allow port [X] through firewall"
  • "Block IP address [X.X.X.X]"
  • "Set up UFW on Ubuntu server"
  • "Create iptables/nftables rules"
  • "Configure bastion host firewall"
  • "Implement egress filtering"

Common Scenarios:

  • Initial server setup and hardening
  • Exposing a new service (web server, API, database)
  • Implementing network segmentation
  • Creating bastion host or jump box
  • Migrating from iptables to nftables
  • Configuring cloud security groups
  • Troubleshooting connectivity issues

Decision Framework: Which Firewall Tool?

Cloud Environments

AWS:

  • Instance-level control → Security Groups (stateful, allow-only rules)
  • Subnet-level enforcement → Network ACLs (stateless, allow + deny rules)
  • Use both for defense-in-depth

GCP:

  • Use VPC Firewall Rules (stateful, priority-based)

Azure:

  • Use Network Security Groups (NSGs) (stateful, priority-based)

Host-Based Linux Firewalls

Ubuntu/Debian + Simplicity:

  • Use UFW (Uncomplicated Firewall) - recommended for most users
  • Front-end for iptables/nftables with simplified syntax

RHEL/CentOS/Fedora:

  • Use firewalld (default on Red Hat ecosystem)
  • Zone-based configuration with dynamic updates

Modern Distro + Advanced Control:

  • Use nftables (best performance, modern standard)
  • O(log n) performance vs iptables O(n)
  • Unified IPv4/IPv6/NAT syntax

Legacy Systems:

  • Use iptables (migrate to nftables when feasible)
  • Required for older kernels (< 4.14)

Kubernetes/Containers

Read the full file on GitHub · 490 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. 9d ago First seen · 490 lines · 67 tokens per session scan A 9f6852203168

Subscribe to this mod's changes

configuring-firewalls is a skill published in the GitHub repository ancoleman/ai-design-components (519 stars, last pushed 9mo ago), licensed MIT. It adds 67 tokens to every session and 3,484 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (asks for root). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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