Iptables常用命令

通常使用的规则

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iptables -A INPUT -i lo -j ACCEPT
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A OUTPUT -j ACCEPT
iptables -A INPUT -p tcp -m tcp -m state --state NEW --dport 22 -j ACCEPT
iptables -A INPUT -p tcp -m tcp -m state --state NEW --dport 80 -j ACCEPT
iptables -A INPUT -p tcp -m tcp -m state --state NEW --dport 443 -j ACCEPT
iptables -A INPUT -j REJECT
iptables -A FORWARD -j REJECT

1. 删除所有现有规则

   1	iptables -F

2. 设置默认的 chain 策略

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   iptables -P INPUT DROP iptables -P FORWARD DROP iptables -P OUTPUT DROP

3. 阻止某个特定的 IP 地址

   1 2	BLOCK_THIS_IP="x.x.x.x" iptables -A INPUT -s "$BLOCK_THIS_IP" -j DRO

4. 允许全部进来的（incoming）SSH

   1 2	iptables -A INPUT -i eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

5. 只允许某个特定网络进来的 SSH

   1 2	iptables -A INPUT -i eth0 -p tcp -s 192.168.200.0/24 --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

6. 允许进来的（incoming）HTTP

   1 2	iptables -A INPUT -i eth0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT

7. 多端口（允许进来的 SSH、HTTP 和 HTTPS）

   1 2	iptables -A INPUT -i eth0 -p tcp -m multiport --dports 22,80,443 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp -m multiport --sports 22,80,443 -m state --state ESTABLISHED -j ACCEPT

8. 允许出去的（outgoing）SSH

   1 2	iptables -A OUTPUT -o eth0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

9. 允许外出的（outgoing）SSH，但仅访问某个特定的网络

   1 2	iptables -A OUTPUT -o eth0 -p tcp -d 192.168.101.0/24 --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

10. 允许外出的（outgoing） HTTPS

    1 2	iptables -A OUTPUT -o eth0 -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A INPUT -i eth0 -p tcp --sport 443 -m state --state ESTABLISHED -j ACCEPT

11. 对进来的 HTTPS 流量做负载均衡

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    iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 0 -j DNAT --to-destination 192.168.1.101:443 iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 1 -j DNAT --to-destination 192.168.1.102:443 iptables -A PREROUTING -i eth0 -p tcp --dport 443 -m state --state NEW -m nth --counter 0 --every 3 --packet 2 -j DNAT --to-destination 192.168.1.103:443

12. 从内部向外部 Ping

    1 2	iptables -A OUTPUT -p icmp --icmp-type echo-request -j ACCEPT iptables -A INPUT -p icmp --icmp-type echo-reply -j ACCEPT

13. 从外部向内部 Ping

    1 2	iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT iptables -A OUTPUT -p icmp --icmp-type echo-reply -j ACCEPT

14. 允许环回（loopback）访问

    1 2	iptables -A INPUT -i lo -j ACCEPT iptables -A OUTPUT -o lo -j ACCEPT

15. 允许 packets 从内网访问外网

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    if eth1 is connected to external network (internet) if eth0 is connected to internal network (192.168.1.x) iptables -A FORWARD -i eth0 -o eth1 -j ACCEPT

16. 允许外出的 DNS

    1 2	iptables -A OUTPUT -p udp -o eth0 --dport 53 -j ACCEPT iptables -A INPUT -p udp -i eth0 --sport 53 -j ACCEPT

17. 允许 NIS 连接

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    rpcinfo -p | grep ypbind ; This port is 853 and 850 iptables -A INPUT -p tcp --dport 111 -j ACCEPT iptables -A INPUT -p udp --dport 111 -j ACCEPT iptables -A INPUT -p tcp --dport 853 -j ACCEPT iptables -A INPUT -p udp --dport 853 -j ACCEPT iptables -A INPUT -p tcp --dport 850 -j ACCEPT iptables -A INPUT -p udp --dport 850 -j ACCEPT

18. 允许某个特定网络 rsync 进入本机

    1 2	iptables -A INPUT -i eth0 -p tcp -s 192.168.101.0/24 --dport 873 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 873 -m state --state ESTABLISHED -j ACCEPT

19. 仅允许来自某个特定网络的 MySQL 的链接

    1 2	iptables -A INPUT -i eth0 -p tcp -s 192.168.200.0/24 --dport 3306 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 3306 -m state --state ESTABLISHED -j ACCEPT

20. 允许 Sendmail 或 Postfix

    1 2	iptables -A INPUT -i eth0 -p tcp --dport 25 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 25 -m state --state ESTABLISHED -j ACCEPT

21. 允许 IMAP 和 IMAPS

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    iptables -A INPUT -i eth0 -p tcp --dport 143 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 143 -m state --state ESTABLISHED -j ACCEPT iptables -A INPUT -i eth0 -p tcp --dport 993 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 993 -m state --state ESTABLISHED -j ACCEPT

22. 允许 POP3 和 POP3S

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    iptables -A INPUT -i eth0 -p tcp --dport 110 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 110 -m state --state ESTABLISHED -j ACCEPT iptables -A INPUT -i eth0 -p tcp --dport 995 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 995 -m state --state ESTABLISHED -j ACCEPT

23. 防止 DoS 攻击

    1	iptables -A INPUT -p tcp --dport 80 -m limit --limit 25/minute --limit-burst 100 -j ACCEPT

24. 设置 422 端口转发到 22 端口

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    iptables -t nat -A PREROUTING -p tcp -d 192.168.102.37 --dport 422 -j DNAT --to 192.168.102.37:22 iptables -A INPUT -i eth0 -p tcp --dport 422 -m state --state NEW,ESTABLISHED -j ACCEPT iptables -A OUTPUT -o eth0 -p tcp --sport 422 -m state --state ESTABLISHED -j ACCEPT

25. 为丢弃的包做日志（Log）

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    iptables -N LOGGING iptables -A INPUT -j LOGGING iptables -A LOGGING -m limit --limit 2/min -j LOG --log-prefix "IPTables Packet Dropped: " --log-level 7 iptables -A LOGGING -j DROP