1.

iptables -P INPUT ACCEPT
iptables -P FORWARD ACCEPT
iptables -P OUTPUT ACCEPT
iptables -F

2.

apt-get purge netfilter-persistent && reboot
或 rm -rf /etc/iptables && reboot

3.

systemctl stop oracle-cloud-agent
systemctl disable oracle-cloud-agent
systemctl stop oracle-cloud-agent-updater
systemctl disable oracle-cloud-agent-updater

4.

systemctl stop firewalld.service
systemctl disable firewalld.service