Configure the loopback interface to accept traffic. Configure all other interfaces to deny traffic to the loopback network (127.0.0.0/8). Loopback traffic is generated between processes on machine and is typically critical to operation of the system. The loopback interface is the only place that loopback network (127.0.0.0/8) traffic should be seen, all other interfaces should ignore traffic on this network as an anti-spoofing measure. Note: Changing firewall settings while connected over network can result in being locked out of the system.
Solution
Run the following commands to implement the loopback rules: # iptables -A INPUT -i lo -j ACCEPT # iptables -A OUTPUT -o lo -j ACCEPT # iptables -A INPUT -s 127.0.0.0/8 -j DROP