iptables is Linux administration tool for IPv4 packet filtering and NAT. One can use iptables/ip6tables to set up, manage, and examine the tables of IPv4 and IPv6 packet filter rules in the Linux kernel. This page shows how to use Iptables to insert the rule at top of tables.

To list iptables rules with line numbers

syntax:
sudo iptables -t filter -L INPUT --line-numbers -n
sudo iptables -t filter -L OUTPUT --line-numbers -n
sudo iptables -t filter -L FORWARD --line-numbers -n
sudo iptables -t nat -L --line-numbers -n

Iptables insert the rule at top of tables Linux syntax

The iptables allows you to APPEND or INSERT or REPLACE firewall rules as follows.

Iptables append firewall rules to the end of the selected chain

The syntax is:

iptables -A chain firewall-rule

Iptables prepend firewall rules to the end of the selected chain

You need to use the following syntax:

iptables -I chain [rule-number] firewall-rule

Linux Iptables insert/prepend rule at top of tables command summary

You need to use the following syntax:

sudo iptables -I chain [rule-number] firewall-rule
 

 

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