View source for Replace firewalld with iptables in CentOS

Stop and disable firewalld
<pre>
# systemctl stop firewalld
# systemctl disable firewalld
</pre>

Install and enable iptables service
<pre>
# yum install iptables-services
# systemctl enable iptables
</pre>

Create simple iptables to allow port 22 by editing '`'/etc/sysconfig/iptables'''
<pre>
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
-A INPUT -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-port-unreachable
COMMIT
</pre>

Start iptables and verify that rules have been applied
<pre>
# systemctl start iptables
# iptables -nL
</pre>