mcpField
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firewall

firewall

github.com/chatermSecurity59130 installsUpdated 34w ago
Repository

About firewall

A firewall configuration skill covering iptables, firewalld, nftables, and ufw. It provides command examples for managing rules, NAT, persistence, common server setups, and troubleshooting.

Key features

  1. 01iptables rule and NAT examples
  2. 02firewalld service and port management
  3. 03ufw rules and default policies
  4. 04Saving and restoring rules
  5. 05Rule and connection troubleshooting

Use cases

  1. 01Allowing web traffic to a server
  2. 02Restricting database access by source IP
  3. 03Configuring port forwarding with NAT
  4. 04Investigating blocked or ineffective rules

Install

Copy the command and run it in a terminal.

$npx skills add https://github.com/chaterm/terminal-skills --skill firewall

After installing, type/firewallin Claude Code to confirm it loaded.

Details

From the project README

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

ufw (Ubuntu)

基础命令
# 启用/禁用
ufw enable
ufw disable

# 状态
ufw status
ufw status verbose
ufw status numbered
规则管理
# 允许端口
ufw allow 22
ufw allow 80/tcp
ufw allow 443/tcp

# 允许服务
ufw allow ssh
ufw allow http

# 允许 IP
ufw allow from 192.168.1.100

# 允许网段到端口
ufw allow from 192.168.1.0/24 to any port 3306

# 拒绝
ufw deny 23

# 删除规则
ufw delete allow 80
ufw delete 3
默认策略
ufw default deny incoming
ufw default allow outgoing

常见场景

场景 1：Web 服务器
# iptables
iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -j DROP

# firewalld
firewall-cmd --add-service=ssh --permanent
firewall-cmd --add-service=http --permanent
firewall-cmd --add-service=https --permanent
firewall-cmd --reload
场景 2：数据库服务器
# 只允许应用服务器访问
iptables -A INPUT -s 192.168.1.10 -p tcp --dport 3306 -j ACCEPT
iptables -A INPUT -s 192.168.1.11 -p tcp --dport 3306 -j ACCEPT
iptables -A INPUT -p tcp --dport 3306 -j DROP
场景 3：限速防护
# 限制 SSH 连接频率
iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m recent --set
iptables -A INPUT -p tcp --dport 22 -m state --state NEW -m recent --update --seconds 60 --hitcount 4 -j DROP

故障排查

问题排查方法
连接被拒检查规则顺序、默认策略
规则不生效检查 --permanent、reload
NAT 不工作检查 ip_forward、FORWARD 链
# 查看计数
iptables -L -n -v

# 日志
iptables -A INPUT -j LOG --log-prefix "IPT_DROP: "
tail -f /var/log/messages | grep IPT_DROP

# 连接跟踪
conntrack -L

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