Open port 3306 on the server

I'd recommend not opening up 3306, and just whitelisting the IP's you want to connect from in CSF this way the port stays closed, but your remote whitelisted IP's can access it.

If you are using CSF its very easy, you can do:

Code:

# csf -a 111.222.333.444

This will allow the IP the ability to access any port regardless if its closed, you can also open only 3306 for a specific IP if you prefer not to allow the IP access to ALL closed ports:

You would have to modify the file: /etc/csf/csf.allow

and add:

Code:

tcp|in|d=3306|s=111.222.333.444

make sure to restart CSF:

Code:

# csf -ra

otherwise, if you are sure you want to open the port up for ALL, you would modify the file: /etc/csf/csf.conf

and add the port 3306 to the line: TCP_IN

example:

Code:

TCP_IN = "20,21,22,25,26,53,80,110,143,443,465,587,993,995,111,2049,2077,2078,2082,2083,2086,2087,2095,2096,3306"

then restart CSF:

Code:

# csf -ra