CentOS 默认iptables配置文件说明

枫之歌

1. [root@37 ~]# cat /etc/sysconfig/iptables
   
2. # Firewall configuration written by system-config-firewall
   
3. # Manual customization of this file is not recommended.
   
4. *nat
   
5. :PREROUTING ACCEPT [0:0]
   
6. :OUTPUT ACCEPT [0:0]
   
7. :POSTROUTING ACCEPT [0:0]
   
8. -A POSTROUTING -o eth+ -j MASQUERADE
   
9. COMMIT
   
10. *filter
    
11. :INPUT ACCEPT [0:0]
    
12. :FORWARD ACCEPT [0:0]
    
13. :OUTPUT ACCEPT [0:0]
    
14. -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
    
15. -A INPUT -p icmp -j ACCEPT
    
16. -A INPUT -i lo -j ACCEPT
    
17. -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
    
18. -A INPUT -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT
    
19. -A INPUT -m state --state NEW -m tcp -p tcp --dport 3306 -j ACCEPT
    
20. -A INPUT -m state --state NEW -m tcp -p tcp --dport 10050 -j ACCEPT
    
21. -A INPUT -m state --state NEW -m udp -p udp --dport 10050 -j ACCEPT
    
22. -A INPUT -m state --state NEW -m tcp -p tcp --dport 10051 -j ACCEPT
    
23. -A INPUT -m state --state NEW -m udp -p udp --dport 10051 -j ACCEPT
    
24. -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT
    
25. -A FORWARD -p icmp -j ACCEPT
    
26. -A FORWARD -i lo -j ACCEPT
    
27. -A FORWARD -o eth+ -j ACCEPT
    
28. -A INPUT -j REJECT --reject-with icmp-host-prohibited
    
29. -A FORWARD -j REJECT --reject-with icmp-host-prohibited
    
30. COMMIT

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求解释这个默认的配置文件中
“：”号开头是什么意思？
结束的“[0:0]”又是什么意思？
“:INPUT ACCEPT [0:0]”这一句又是什么意思？
每张表结束处都有个COMMIT，这又是什么意思？