Information
Configure the loopback interface to accept traffic. Configure all other interfaces to deny traffic to the loopback network (::1).
Rationale:
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 (::1) 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:
# ip6tables -A INPUT -i lo -j ACCEPT
# ip6tables -A OUTPUT -o lo -j ACCEPT
# ip6tables -A INPUT -s ::1 -j DROP