MariaDB


How to temporarily open MySQL / MariaDB port on CentOS 7 firewall

Recently, we came across a CentOS 7 that was executing MariaDB (MySQL) server. The Database Administrators needed a way to open to the port and allow connections to the SQL server from outside the machine.
As they did not have a specific IP from which they would connect, we provided the following solution.

To temporarily open port 3306

firewall-cmd --add-port=3306/tcp;

To close the port 3306 (method A)

firewall-cmd --remove-port=3306/tcp;

or reload firewalld which will cause it to loose all changes that are not permanent (method B)

firewall-cmd  --reload;

firewalld (Dynamic Firewall Manager) tool provides a dynamically managed firewall. The tool enables network/firewall zones to define the trust level of network connections and/or interfaces. It has support both for IPv4 and IPv6 firewall settings. Also, it supports Ethernet bridges and allow you to separate between runtime and permanent configuration options. Finally, it supports an interface for services or applications to add firewall rules directly.

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Easy way to repair and optimize core WordPress MySql DataBase Tables

To manually repair and optimize the core WordPress tables of your MySql (or MariaDB) database:

A) edit your wp-config.php and add

define('WP_ALLOW_REPAIR', true);

right before the line

/* That's all, stop editing! Happy blogging. */

B) Visit the following link (and replace example.com with the domain or the IP of your site installation)

https://example.com/wp-admin/maint/repair.php

C) Press the Repair and Optimize Database button and wait for some time (depending on the size of the core tables of your installation)

D) Once the above step is done, remove or comment out (by adding a # at the beginning of the line) the line:

define('WP_ALLOW_REPAIR', true);

You need to do this step to to prevent this page (which could potentially take a lot of resources) from being used by unauthorized users.