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littlebigman 03-26-2011 07:51 AM

Netfilter + iptables?

I've never used iptables, and would like to add it to a telephony server so as to use an application like Fail2ban to block IP's that are trying to hack it.

According to Wikipedia, it seems like Netfilter is some code in the kernel, while iptables consists in kernel modules and some user-land binaries:

Is that how it works? If not, could someone briefly explain how those two parts work together?

Thank you.

corp769 03-26-2011 07:55 AM


netfilter is a set of hooks inside the Linux kernel that allows kernel modules to register callback functions with the network stack. A registered callback function is then called back for every packet that traverses the respective hook within the network stack.

iptables is a generic table structure for the definition of rulesets. Each rule within an IP table consists of a number of classifiers (iptables matches) and one connected action (iptables target).
Taken from the netfilter site. Iptables is netfilter; You define the rules for iptables, and the kernel, along with iptables itself, will do what you want it to do.

littlebigman 03-28-2011 07:01 AM

Thanks for the clarification.

corp769 03-28-2011 01:25 PM

Not a problem.


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