甲骨文如何正确开放端口
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 && rebootCentos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原文地址：https://www.vediotalk.com/archives/39863
甲骨文root密码登录
centos 默认登录账户是 opc
ubuntu 默认登录账户是 ubuntu
然后执行下面的脚本，开启root登陆，密码为 22333
echo root:22333 |sudo chpasswd root
sudo sed -i 's/^#\?PermitRootLogin.*/PermitRootLogin yes/g' /etc/ssh/sshd_config;
sudo sed -i 's/^#\?PasswordAuthentication.*/PasswordAuthentication yes/g' /etc/ssh/sshd_config;
sudo service sshd restart
