firewall

firewall is a skill for Claude Code, Codex from chaterm/terminal-skills. It costs 7 tokens per session (1,623 once invoked), scanned A, original, Apache-2.0.

A set of Linux instructions for configuring firewalls, which allow or block network traffic according to rules.

In plain words
What is it for?
Use it to inspect and change iptables, firewalld, nftables, or ufw rules; allow services such as SSH and HTTPS; block traffic; and configure network address translation and port forwarding.
Why use it?
It helps limit which connections can reach a server, reducing unwanted access and controlling traffic between networks.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to inspect and change iptables, firewalld, nftables, or ufw rules; allow services such as SSH and HTTPS; block traffic; and configure network address translation and port forwarding.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/chaterm/terminal-skills/firewall
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 chaterm/terminal-skills --skill firewall
Clone the repo
git clone --depth 1 https://github.com/chaterm/terminal-skills

Made for: Claude Code, Codex.

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 firewall

README.md
[![agentmods](https://agentmods.dev/badge/skills/chaterm/terminal-skills/firewall/github.svg)](https://agentmods.dev/skills/chaterm/terminal-skills/firewall)
Your own site
<a href="https://agentmods.dev/skills/chaterm/terminal-skills/firewall"><img src="https://agentmods.dev/badge/skills/chaterm/terminal-skills/firewall/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.

agentmods 80×15 button for firewall

Your own site · 80×15
<a href="https://agentmods.dev/skills/chaterm/terminal-skills/firewall"><img src="https://agentmods.dev/badge/skills/chaterm/terminal-skills/firewall.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 7 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,623 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. 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 $0.00007 $0.01623
Opus 5 $0.00003 $0.00812
Sonnet 5 $0.00001 $0.00325
Haiku 4.5 $0.00001 $0.00162

Measured 9d ago against content hash 9d728772e49b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

firewall 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 9d 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.

security/firewall/SKILL.md · 245 lines

How it starts

The opening of the file, as written. The whole thing — 245 lines — stays where its author put it; the contents beside it link to each section on GitHub.

防火墙配置

概述

iptables、firewalld、nftables、ufw 防火墙配置技能。

iptables

基础命令

# 查看规则
iptables -L -n -v
iptables -L -n --line-numbers
iptables -t nat -L -n -v

# 清空规则
iptables -F
iptables -X
iptables -t nat -F

# 默认策略
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT ACCEPT

常用规则

# 允许回环
iptables -A INPUT -i lo -j ACCEPT

# 允许已建立连接
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

# 允许 SSH
iptables -A INPUT -p tcp --dport 22 -j ACCEPT

# 允许 HTTP/HTTPS
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j ACCEPT

# 允许特定 IP
iptables -A INPUT -s 192.168.1.100 -j ACCEPT

# 允许网段
iptables -A INPUT -s 192.168.1.0/24 -p tcp --dport 3306 -j ACCEPT

# 拒绝其他
iptables -A INPUT -j DROP

删除规则

# 按行号删除
iptables -D INPUT 3

# 按规则删除
iptables -D INPUT -p tcp --dport 80 -j ACCEPT

NAT 配置

# 开启转发
echo 1 > /proc/sys/net/ipv4/ip_forward

# SNAT
iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

# DNAT 端口转发
iptables -t nat -A PREROUTING -p tcp --dport 8080 -j DNAT --to 192.168.1.10:80
iptables -A FORWARD -p tcp -d 192.168.1.10 --dport 80 -j ACCEPT

保存规则

# Debian/Ubuntu
iptables-save > /etc/iptables/rules.v4
iptables-restore < /etc/iptables/rules.v4

# CentOS/RHEL
service iptables save

firewalld

基础命令

# 状态
systemctl status firewalld
firewall-cmd --state

# 重载
firewall-cmd --reload

# 查看区域
firewall-cmd --get-zones
firewall-cmd --get-default-zone
firewall-cmd --get-active-zones

服务管理

# 查看服务
firewall-cmd --list-services
firewall-cmd --get-services

# 添加服务
firewall-cmd --add-service=http --permanent
firewall-cmd --add-service=https --permanent

# 删除服务
firewall-cmd --remove-service=http --permanent

端口管理

# 查看端口
firewall-cmd --list-ports

# 添加端口
firewall-cmd --add-port=8080/tcp --permanent
firewall-cmd --add-port=5000-5100/tcp --permanent

# 删除端口
firewall-cmd --remove-port=8080/tcp --permanent

富规则

# 允许特定 IP
firewall-cmd --add-rich-rule='rule family="ipv4" source address="192.168.1.100" accept' --permanent

# 允许网段访问端口
firewall-cmd --add-rich-rule='rule family="ipv4" source address="192.168.1.0/24" port port="3306" protocol="tcp" accept' --permanent

# 拒绝 IP
firewall-cmd --add-rich-rule='rule family="ipv4" source address="10.0.0.100" reject' --permanent

Read the full file on GitHub · 245 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 · 245 lines · 7 tokens per session scan A 9d728772e49b

Subscribe to this mod's changes

firewall is a skill published in the GitHub repository chaterm/terminal-skills (58 stars, last pushed 6mo ago), licensed Apache-2.0. It adds 7 tokens to every session and 1,623 once invoked, about $0.0000 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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