删除、关闭、打开各自系统的无用附件、防火墙、端口及规则

Ubuntu系统下：

开放所有端口

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

Ubuntu镜像默认设置了Iptable规则，关闭它

apt-get purge netfilter-persistent
reboot

或者强制删除

rm -rf /etc/iptables && reboot

Centos系统下：

删除多余附件

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

停止firewall

systemctl stop firewalld.service

禁止firewall开机启动

systemctl disable firewalld.service