Linux Firewall with iptables and firewalld
In this article will be covering details regarding iptables and firewalld which helps in Linux firewall management. We will also be looking at how to enable specific ports (1521 for Oracle) inside iptables.
Read more about Linux iptables vs Linux firewall
Linux Firewall status
The Linux firewalld command will let you check Linux firewall status. It will show you the current status Active in case firewall is running
systemctl status firewalld
Linux Disable Firewall
For practicing Oracle on Linux, you might need to stop the Linux firewall so that you can connect applications to database listener. Below commands will permanently disable Linux firewall
service firewalld stop systemctl disable firewalld
Linux Enable Firewall
Just in case you would like to enable Linux firewall after disabling it, use below commands
service firewalld start systemctl enable firewalld
Enable Ports in Linux
On some servers, port 1521 will not be enabled by default because of security reasons. You can enable this specific port inside linux using below commands.
Enable 1521 Port in Linux
If you are working on Oracle Linux 5 or 6 version, use Linux iptables command to enable specific ports as root user
iptables -I INPUT -p tcp --dport 1521 -j ACCEPT
If you would like to open any specific port in Linux, just replace the port number (1521) with new port number.
Enable Port Range in Linux
To open multiple port ranges in Linux, use below command
iptables -A INPUT -p tcp -m multiport --dports 7101:7200,4889:4898,1159,4899:4908,7788:7809,3872,1830:1849 -j ACCEPT
Enable Port in Oracle Linux 7
In some Linux versions, below command works fine
firewall-cmd --permanent --add-port=1521/tcp