Linux iptables opens the MySQL port to allow remote access

Modify the firewall configuration file:
VI/etc/sysconfig/iptables

Add the following line:

-A RH-Firewall-1-INPUT-M State-State new-m tcp-p tcp-dport 3306-J accept
If you want to activate ports such as 21, you only need to replace 3306 with the ports to be opened, such as 21.
After configuration, restart iptable
Service iptables restart
Then you can access MySQL from other machines.

Note:
-A RH-Firewall-1-INPUT-M state -- state new-m tcp-p tcp -- dport 3306-J accept
-A RH-Firewall-1-INPUT-J reject -- reject-with ICMP-host-prohibited

-A RH-Firewall-1-INPUT-J reject -- reject-with ICMP-host-prohibited
It indicates that ICMP access is denied. If other packets are returned, an error is returned indicating that access is disabled on the host.

The line for enabling port 3306 must be before ICMP-host-prohibited.