Linux 篇：实际生产环境中的 iptables 脚本

比眉伴天荒 2024-03-16 20:32 54阅读 0赞

\`\`\` 创建 iptables.sh 脚本

\[root@Jaking ~\]\# vim iptables.sh

## !/bin/bash ##

## 清空 filter 表和 nat 表 ##

iptables -F iptables -t nat -F

## 关掉 firewalld ##

systemctl stop firewalld &>/dev/null systemctl disable firewalld &>/dev/null

## 以下两行允许某些调用 localhost 的应用访问 ##

iptables -A INPUT -i lo -j ACCEPT \#规则1 iptables -A INPUT -s 127.0.0.1 -d 127.0.0.1 -j ACCEPT \#规则2

## 以下一行允许从其他地方 ping ##

iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT \#规则3

## 以下一行允许从其他主机、网络设备发送 MTU 调整的报文 ##

## 在一些情况下，例如通过 IPSec VPN 隧道时，主机的 MTU 需要动态减小 ##

iptables -A INPUT -p icmp --icmp-type fragmentation-needed -j ACCEPT \#规则4

## 以下两行分别允许所有来源访问 TCP 80,443 端口 ##

iptables -A INPUT -p tcp --dport 80 -j ACCEPT \#规则5 iptables -A INPUT -p tcp --dport 443 -j ACCEPT \#规则6

## 以下一行允许所有来源访问 UDP 80,443 端口 ##

iptables -A INPUT -p udp -m multiport --dports 80,443 -j ACCEPT \#规则7

## 以下一行允许 192.168.1.63 来源的 IP 访问 TCP 22 端口(OpenSSH) ##

iptables -A INPUT -p tcp -s 192.168.1.63 --dport 22 -j ACCEPT \#规则8

## 以下一行允许 192.168.1.3(发起SSH连接的系统对应网卡的IP) 来源的 IP 访问 TCP 22 端口(OpenSSH) ##

## 如果是在远程终端跑本脚本，最好开启以下一行以防被踢掉 ##

## 另一种更加简便的方式：iptables -I INPUT -p tcp --dport 22 -j ACCEPT ##

iptables -A INPUT -p tcp -s 192.168.1.3 --dport 22 -j ACCEPT \#规则9

## 以下一行允许 192.168.1.26 来源的 IP 访问 UDP 161 端口(SNMP) ##

iptables -A INPUT -p udp -s 192.168.1.26 --dport 161 -j ACCEPT \#规则10

## 配置 NAT ##

## 启用内核路由转发功能 ##

echo 1 > /proc/sys/net/ipv4/ip*forward echo "net.ipv4.ip*forward = 1" > /etc/sysctl.conf sysctl -p &>/dev/null

## 配置源地址转换 SNAT ##

## 将 192.168.2.0/24 转换成 192.168.1.63 ##

iptables -t nat -A POSTROUTING -s 192.168.2.0/24 -j SNAT --to 192.168.1.63 \#规则11

## 配置目的地址转换 DNAT ##

## 将 192.168.1.63 的 80 端口请求转发到 192.168.2.2 的 80 端口 ##

iptables -t nat -A PREROUTING -d 192.168.1.63 -p tcp --dport 80 -j DNAT --to 192.168.2.2:80 \#规则12

## 以下一行禁止所有其他的进入流量 ##

iptables -A INPUT -j DROP \#规则13

## 以下一行允许本机响应规则编号为 1-12 的数据包发出 ##

iptables -A OUTPUT -m state --state ESTABLISHED -j ACCEPT \#规则14

## 以下一行禁止本机主动发出外部连接 ##

iptables -A OUTPUT -j DROP \#规则15

## 以下一行禁止本机转发数据包 ##

iptables -A FORWARD -j DROP \#规则16

## 固化 iptables ##

iptables-save > /etc/sysconfig/iptables

\[root@Jaking ~\]\# chmod 755 iptables.sh 测试

\[root@Jaking ~\]\# ./iptables.sh \[root@Jaking ~\]\# \[root@Jaking ~\]\# \[root@Jaking ~\]\# iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination  
ACCEPT all -- anywhere anywhere  
ACCEPT all -- localhost localhost  
ACCEPT icmp -- anywhere anywhere icmp echo-request ACCEPT icmp -- anywhere anywhere icmp fragmentation-needed ACCEPT tcp -- anywhere anywhere tcp dpt:http ACCEPT tcp -- anywhere anywhere tcp dpt:https ACCEPT udp -- anywhere anywhere multiport dports http,https ACCEPT tcp -- 192.168.1.63 anywhere tcp dpt:ssh ACCEPT tcp -- 192.168.1.3 anywhere tcp dpt:ssh ACCEPT udp -- 192.168.1.26 anywhere udp dpt:snmp DROP all -- anywhere anywhere

Chain FORWARD (policy ACCEPT) target prot opt source destination  
DROP all -- anywhere anywhere

Chain OUTPUT (policy ACCEPT) target prot opt source destination  
ACCEPT all -- anywhere anywhere state ESTABLISHED DROP all -- anywhere anywhere  
\[root@Jaking ~\]\# iptables -L --line-number Chain INPUT (policy ACCEPT) num target prot opt source destination  
1 ACCEPT all -- anywhere anywhere  
2 ACCEPT all -- localhost localhost  
3 ACCEPT icmp -- anywhere anywhere icmp echo-request 4 ACCEPT icmp -- anywhere anywhere icmp fragmentation-needed 5 ACCEPT tcp -- anywhere anywhere tcp dpt:http 6 ACCEPT tcp -- anywhere anywhere tcp dpt:https 7 ACCEPT udp -- anywhere anywhere multiport dports http,https 8 ACCEPT tcp -- 192.168.1.63 anywhere tcp dpt:ssh 9 ACCEPT tcp -- 192.168.1.3 anywhere tcp dpt:ssh 10 ACCEPT udp -- 192.168.1.26 anywhere udp dpt:snmp 11 DROP all -- anywhere anywhere

Chain FORWARD (policy ACCEPT) num target prot opt source destination  
1 DROP all -- anywhere anywhere

Chain OUTPUT (policy ACCEPT) num target prot opt source destination  
1 ACCEPT all -- anywhere anywhere state ESTABLISHED 2 DROP all -- anywhere anywhere  
\[root@Jaking ~\]\# iptables -t nat -L Chain PREROUTING (policy ACCEPT) target prot opt source destination  
DNAT tcp -- anywhere 192.168.1.63 tcp dpt:http to:192.168.2.2:80

Chain INPUT (policy ACCEPT) target prot opt source destination

Chain OUTPUT (policy ACCEPT) target prot opt source destination

Chain POSTROUTING (policy ACCEPT) target prot opt source destination  
SNAT all -- 192.168.2.0/24 anywhere to:192.168.1.63 \[root@Jaking ~\]\# iptables -t nat -L --line-number Chain PREROUTING (policy ACCEPT) num target prot opt source destination  
1 DNAT tcp -- anywhere 192.168.1.63 tcp dpt:http to:192.168.2.2:80

Chain INPUT (policy ACCEPT) num target prot opt source destination

Chain OUTPUT (policy ACCEPT) num target prot opt source destination

Chain POSTROUTING (policy ACCEPT) num target prot opt source destination  
1 SNAT all -- 192.168.2.0/24 anywhere to:192.168.1.63

iptables 的清空和恢复

\[root@Jaking ~\]\# iptables -F \[root@Jaking ~\]\# iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination

Chain FORWARD (policy ACCEPT) target prot opt source destination

Chain OUTPUT (policy ACCEPT) target prot opt source destination  
\[root@Jaking ~\]\# iptables -t nat -F \[root@Jaking ~\]\# iptables -t nat -L Chain PREROUTING (policy ACCEPT) target prot opt source destination

Chain INPUT (policy ACCEPT) target prot opt source destination

Chain OUTPUT (policy ACCEPT) target prot opt source destination

Chain POSTROUTING (policy ACCEPT) target prot opt source destination \[root@Jaking ~\]\# iptables-restore < /etc/sysconfig/iptables \[root@Jaking ~\]\# iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination  
ACCEPT all -- anywhere anywhere  
ACCEPT all -- localhost localhost  
ACCEPT icmp -- anywhere anywhere icmp echo-request ACCEPT icmp -- anywhere anywhere icmp fragmentation-needed ACCEPT tcp -- anywhere anywhere tcp dpt:http ACCEPT tcp -- anywhere anywhere tcp dpt:https ACCEPT udp -- anywhere anywhere multiport dports http,https ACCEPT tcp -- 192.168.1.63 anywhere tcp dpt:ssh ACCEPT tcp -- 192.168.1.3 anywhere tcp dpt:ssh ACCEPT udp -- 192.168.1.26 anywhere udp dpt:snmp DROP all -- anywhere anywhere

Chain FORWARD (policy ACCEPT) target prot opt source destination  
DROP all -- anywhere anywhere

Chain OUTPUT (policy ACCEPT) target prot opt source destination  
ACCEPT all -- anywhere anywhere state ESTABLISHED DROP all -- anywhere anywhere  
\[root@Jaking ~\]\# iptables -t nat -L Chain PREROUTING (policy ACCEPT) target prot opt source destination  
DNAT tcp -- anywhere 192.168.1.63 tcp dpt:http to:192.168.2.2:80

Chain INPUT (policy ACCEPT) target prot opt source destination

Chain OUTPUT (policy ACCEPT) target prot opt source destination

Chain POSTROUTING (policy ACCEPT) target prot opt source destination  
SNAT all -- 192.168.2.0/24 anywhere to:192.168.1.63 \`\`\`