Add the following line in your /etc/csf/csf.allow
tcp|in|d=3306|s=192.168.1.1
tcp|out|d=3306|d=192.168.1.3
Restart csf with : csf -r
This will allow incoming/outgoing connections to port 3306
Add the following line in your /etc/csf/csf.allow
tcp|in|d=3306|s=192.168.1.1
tcp|out|d=3306|d=192.168.1.3
Restart csf with : csf -r
This will allow incoming/outgoing connections to port 3306