You may already know that CentOS 7 use Firewalld as the front end interface to manage netfilter firewall and not Iptables.
So the purpose of this tutorial is to learn how to install and configure Iptables on CentOS 7 Linux, since many of the Linux system administrators still prefer Iptables over Firewalld. So do the following steps.
It is important to Know how to backup iptables firewall rules on your Linux server. Iptables firewall is a very sensitive thing, with one mistake you could mess up your entire network system, especially if you have configured your Linux server as a router. So you should always backup current configuration before you make any changes.
I’am Trying to write a simple firewall rule using the iptables negation (not equal). Simply What I want is to allow any traffic which is not UDP.
But I get the error “Using intrapositioned negation” when I add the rule. Following is the complete error message.
I am having repodata problem in my CentOS virtual Machine. I can’t update or install software using yum command. Only get the following yum pycurl error 22 message.
You Should Be Careful when you flush iptables rules, because if you do not flush iptables properly, you could end up being locked out of your server.
Use following bash script to flush iptables rules, instead of applying iptables -F Command Directly to the system.
Ubuntu uses UFW (Ubuntu Firewall) as the Frontend tool to manage netfilter firewall rules by default. But if you are more familiar with iptables, no problem we can easily install and configure iptables on Ubuntu Server. So lets see how to install iptables on Ubuntu server 14.04.