常用的 Linux iptables 规则

一些常用的 Linux iptables 规则，请根据自己的具体需要再修改。

# 1. 删除所有现有规则

1 iptables - F

# 2. 设置默认的 chain 策略

1 2 3 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 DROP

# 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

1 2 3 #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

1 2 3 # 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

1 2 3 4 5 6 7 # 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

1 2 3 4 #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

1 2 3 4 #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

1 2 3 #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）

1 2 3 4 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