Iptables (1)

This article describesIptablesFor more information, see the following section!

I. Iptables Concept

Iptables is an IP information packet filtering system integrated with the latest Linux kernel 2.6.x. If the Linux system is connected to the Internet or LAN, server, or a proxy server connected to the LAN and Internet, the system facilitates better control of IP packet filtering and firewall configuration on the Linux system.

The netfilter/iptables IP information packet filtering system is a powerful tool that can be used to add, edit, and remove rules. These rules are used for filtering and determining information packets, rules of the firewall. These rules are stored in a dedicated information packet filtering table, which is integrated into the Linux kernel. In the information packet filtering table, rules are grouped in a chain.

Although the netfilter/iptables IP information packet filtering system is called a single entity, it actually consists of two components: netfilter and iptables.

The netfilter component, also known as the kernel space (kernelspace), is a part of the kernel and consists of information packet filtering tables that contain the rule set used by the kernel to control information packet filtering.

The iptables component is a tool, also known as userspace, which makes it easy to insert, modify, and remove rules from the information package filter table. Unless you are using Red Hat Linux 7.1 or later, you need to download the tool and install it.

II,Related commands

Use iptables-ADC to specify the chain rules.-A Add-D Delete-C modify

Iptables-[RI] chain rule num rule-specification [option]

Use iptables-RI to specify the sequence of rules

Iptables-D chain rule num [option]

Deletes a specified rule.

Iptables-[LFZ] [chain] [option]

Use iptables-LFZ chain name [Option]

Iptables-[NX] chain

Use-NX to specify a chain

Iptables-P chain target [options]

Default target of the specified chain

Iptables-E old-chain-name new-chain-name

-E old chain name New Chain name

Replace old chain names with new chain names