超级实用的 iptables 防火墙脚本
本文档详细介绍生产环境中超级实用的iptables脚本。
创建 iptables.sh 脚本
# vim iptables.sh #!/bin/bash#清空 filter 表和 nat 表iptables -Fiptables -t nat -F#关掉 firewalldsystemctl stop firewalld &>/dev/nullsystemctl 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1iptables -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 pingiptables -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5iptables -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 ACCEPTiptables -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_forwardecho "net.ipv4.ip_forward = 1" > /etc/sysctl.confsysctl -p &>/dev/null#配置源地址转换 SNAT #将 192.168.2.0/24 转换成 192.168.1.63iptables -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 iptablesiptables-save > /etc/sysconfig/iptables# chmod 755 iptables.sh测试
# ./iptables.sh # # # iptables -LChain INPUT (policy ACCEPT)target prot opt source destination ACCEPT all--anywhere anywhere ACCEPT all--localhost localhost ACCEPT icmp --anywhere anywhere icmp echo-requestACCEPT icmp --anywhere anywhere icmp fragmentation-neededACCEPT tcp--anywhere anywhere tcp dpt:httpACCEPT tcp--anywhere anywhere tcp dpt:httpsACCEPT udp--anywhere anywhere multiport dports http,httpsACCEPT tcp--192.168.1.63 anywhere tcp dpt:sshACCEPT tcp--192.168.1.3 anywhere tcp dpt:sshACCEPT udp--192.168.1.26 anywhere udp dpt:snmpDROP 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 ESTABLISHEDDROP all--anywhere anywhere # iptables -L --line-numberChain INPUT (policy ACCEPT)numtarget prot opt source destination 1 ACCEPT all--anywhere anywhere 2 ACCEPT all--localhost localhost 3 ACCEPT icmp --anywhere anywhere icmp echo-request4 ACCEPT icmp --anywhere anywhere icmp fragmentation-needed5 ACCEPT tcp--anywhere anywhere tcp dpt:http6 ACCEPT tcp--anywhere anywhere tcp dpt:https7 ACCEPT udp--anywhere anywhere multiport dports http,https8 ACCEPT tcp--192.168.1.63 anywhere tcp dpt:ssh9 ACCEPT tcp--192.168.1.3 anywhere tcp dpt:ssh10 ACCEPT udp--192.168.1.26 anywhere udp dpt:snmp11 DROP all--anywhere anywhere Chain FORWARD (policy ACCEPT)numtarget prot opt source destination 1 DROP all--anywhere anywhere Chain OUTPUT (policy ACCEPT)numtarget prot opt source destination 1 ACCEPT all--anywhere anywhere state ESTABLISHED2 DROP all--anywhere anywhere # iptables -t nat -LChain PREROUTING (policy ACCEPT)target prot opt source destination DNAT tcp--anywhere 192.168.1.63 tcp dpt:http to:192.168.2.2:80Chain 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# iptables -t nat -L --line-numberChain PREROUTING (policy ACCEPT)numtarget prot opt source destination 1 DNAT tcp--anywhere 192.168.1.63 tcp dpt:http to:192.168.2.2:80Chain INPUT (policy ACCEPT)numtarget prot opt source destination Chain OUTPUT (policy ACCEPT)numtarget prot opt source destination Chain POSTROUTING (policy ACCEPT)numtarget prot opt source destination 1 SNAT all--192.168.2.0/24 anywhere to:192.168.1.63iptables 的清空和恢复
# iptables -F# iptables -LChain 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 # iptables -t nat -F# iptables -t nat -LChain 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 # iptables-restore < /etc/sysconfig/iptables# iptables -LChain INPUT (policy ACCEPT)target prot opt source destination ACCEPT all--anywhere anywhere ACCEPT all--localhost localhost ACCEPT icmp --anywhere anywhere icmp echo-requestACCEPT icmp --anywhere anywhere icmp fragmentation-neededACCEPT tcp--anywhere anywhere tcp dpt:httpACCEPT tcp--anywhere anywhere tcp dpt:httpsACCEPT udp--anywhere anywhere multiport dports http,httpsACCEPT tcp--192.168.1.63 anywhere tcp dpt:sshACCEPT tcp--192.168.1.3 anywhere tcp dpt:sshACCEPT udp--192.168.1.26 anywhere udp dpt:snmpDROP 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 ESTABLISHEDDROP all--anywhere anywhere # iptables -t nat -LChain PREROUTING (policy ACCEPT)target prot opt source destination DNAT tcp--anywhere 192.168.1.63 tcp dpt:http to:192.168.2.2:80Chain 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总结
以上就是生产环境中超级实用的iptables脚本，这个脚本可以直接拿去用，不过请谨慎操作！本文原创地址：https://www.linuxprobe.com/super-practical-iptables.html编辑：传棋，审核员：逄增宝
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