What is iptables?

iptables acts like a built-in firewall in older version of Linux.it consists of three important tables i.e., filter, nat and mangle . filter table :just filter the packets and its the default table of iptables .we can set the rules in filter table, Either we want to accept/reject the packet of any specific ip address. It's our choice we want to allow or block.. nat:as it name shows, uses for address translation. mangle :uses for alternation/modification sequence. We can label/mark it as we set the priority of different process.