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Linux Iptables

Linux comes with a firewall called netfilter, which is controlled by iptables. Here, I will explain the useful iptables commands for system admins and a super user with bash shell. Please remember that a wrong command will disconnect you from the system and will block your access to the server.

iptables -L -n

To display the iptables status and rules.

iptables -n -L -v –line-numbers

To inspect the firewall rules with line numbers.

service iptables start/stop/restart

To start / stop / restart iptables.

iptables -F – to flush the rules

iptables -X – to delete a chain rule.

iptables -D INPUT 4 – to delete the rule number 4.

iptables -L INPUT -n –line-numbers – to display the rules with line numbers.

iptables -A INPUT -s IP-address -j DROP – Rule for dropping connection from the IP-address.

Save the rules by the command,

service iptables save

man iptables – will give you a help section about how to use iptables commands.