Before you say It's duplicate... read! I wanted to use iptables to allow only 1 IP, but there were some issues with "state" whatever it means, and persistence of iptables.
Many people advised UFW, but I want zombie box, applied
sudo ufw default deny incoming
sudo ufw default deny outgoing
ping works, DNS works, how can I burn all using UFW but keep applications responsive based on "state" "lo" https://unix.stackexchange.com/a/11870/194331
"For example, not allowing -i lo and -o lo will certainly cause problems for certain applications"
I don't need DNS and PING and anything, I put domain name into hosts file and I want to allow 100% only 1 IP over 443 port, no extras. Possible with UFW?
UPDATE I found this very helpful, it explains what "lo" means https://www.digitalocean.com/community/tutorials/how-to-set-up-a-basic-iptables-firewall-on-centos-6
I seems like I'm going towards iptables, but if someone is UFW master, please answer.