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Mohammad Ali Akbari
Asked: 2013-02-07 10:15:00 +0800 CST

What's the relation between iptables and firewall?

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I try opening my dns port by following rules:

iptables -A INPUT -p udp -m state --state NEW --dport 53 -j ACCEPT
iptables -A INPUT -p tcp -m state --state NEW --dport 53 -j ACCEPT
service iptables save
service iptables restart

But It not works, then I try Opening DNS from following:

system-config-firewall-tui

And it works.

What's the relation between iptables and firewall?

iptables

2 Answers

  1. Best Answer

    The system-config-firewall is just a mere frontend for iptables, which is the frontend for netfilter, the firewall in the linux kernel. Anyway your rule to open the DNS is wrong, it should be:

    iptables -I INPUT -p udp -m state --state NEW --dport 53 -j ACCEPT
iptables -I INPUT -p tcp -m state --state NEW --dport 53 -j ACCEPT

    You have to use the -I option, which means insert at the beginning of the chain. If your last rule prior the append says discard all traffic, then your new rule will never be invoked.

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  2. You can check if the command you executed is effective by running the below query.

    iptables -L

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