iptables rules to ask for password for new connections
I'm writing an iptables ruleset and I wonder if there's any rules that will prompt for password if a user is to establish a new connection. I'm trying to build a modbus firewall, therefore I would like to have only 'established connections' to pass through the firewall, while 'new connections' will be prompt for password. Is it possible?
I hope someone can help! Thanks..