If your new to linux, ufw is very useful tool. Really simple to install with ubuntu.
However, should you choose to get rid of it for some reason, it leaves behind quite a mess.
Here is a quick script to clean up the mess.
Here is the whole process as a bash script:
#!/usr/bin/bash
iptables -P INPUT ACCEPT
iptables -X ufw-user-outputiptables -X ufw-user-logging-outputiptables -X ufw-user-logging-inputiptables -X ufw-user-logging-forwardiptables -X ufw-user-limit-acceptiptables -X ufw-user-limitiptables -X ufw-user-inputiptables -X ufw-user-forwardiptables -X ufw-track-outputiptables -X ufw-track-inputiptables -X ufw-skip-to-policy-outputiptables -X ufw-skip-to-policy-inputiptables -X ufw-skip-to-policy-forwardiptables -X ufw-reject-outputiptables -X ufw-reject-inputiptables -X ufw-reject-forwardiptables -X ufw-not-localiptables -X ufw-logging-denyiptables -X ufw-logging-allowiptables -X ufw-before-outputiptables -X ufw-before-logging-outputiptables -X ufw-before-logging-inputiptables -X ufw-before-logging-forwardiptables -X ufw-before-inputiptables -X ufw-before-forwardiptables -X ufw-after-outputiptables -X ufw-after-logging-outputiptables -X ufw-after-logging-inputiptables -X ufw-after-logging-forwardiptables -X ufw-after-inputiptables -X ufw-after-forwardapt-get remove ufw#As a basic firewall I’d recommend the following:iptables -Fiptables -A INPUT -m state –state RELATED,ESTABLISHED -j ACCEPTiptables -A INPUT -i lo -j ACCEPTiptables -A INPUT -p tcp -m tcp –dport 80 -j ACCEPTiptables -A INPUT -p tcp -m tcp –dport 443 -j ACCEPTiptables -A INPUT -p tcp -m tcp –dport 13160-j ACCEPTiptables -A INPUT -d XX_REPLACE_WITH_YOUR_SERVER_IP/32 -p icmp -m icmp –icmp-type 8 -m state –state NEW,RELATED,ESTABLISHED -j ACCEPTiptables -A INPUT -d XX_REPLACE_WITH_YOUR_SERVER_IP/32 -p icmp -m icmp –icmp-type 0 -m state –state RELATED,ESTABLISHED -j ACCEPTiptables -P INPUT DROPiptables -P FORWARD DROPiptables -P OUTPUT ACCEPT
Then remove the custom ufw chains, flush all existing rules, accept established connections, accept all connections on loopback device, accept all connects to ports 80(http),443(https), and 22(sshd)