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Tip: Be sure you've wrapped all MariaDB port access using a TLS cert, else you'll be hacked... if any of your packets leak through any public IPs.<br />
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Easy way to determine this is working.<br />
<br />
1) Disable your firewall (flush all rules).<br />
<br />
2) Test connecting to 127.0.0.1:3306<br />
<br />
3) Test connecting to IP:3306<br />
<br />
4) Then enable your firewall (activate all rules).<br />
<br />
5) Then retest #2 + #3 again.<br />
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6) Next you'll have to check your routing.<br />
<br />
7) Then go through the equivalent of #2 + #3 on every piece of gear between your database instance IP + your application code IP.
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arnold

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Aside: There's rarely any good reason to access a database instance over an IP.<br />
<br />
This creates massive problems<br />
<br />
1) Packet flow must by TLS wrapped to maintain security.<br />
<br />
2) Since #1 is required, if you're running a CMS, for example WordPress, which does a connect/disconnect for every SQL statement, visitors will see this as slowness on their end.<br />
<br />
3) Speed/Stability of database access becomes set by the speed/quality of packet flow over all networks involved, rather than using a local domain socket, so this creates slow visitor experience + every time a network has a slight problem (normally all day, every day)... TCP will recover from the problem + the connection will normally remain stable. Problem is, this can cause increased slowness, just like #2.<br />
<br />
4) You're only prayer for this to work well, will be to run dedicated servers on fast networks where physical machines/containers (for your database instance + application code instance) are very close to each other.<br />
<br />
Be sure you understand all the considerations of working with IP based database instances, before you invest much time into fixing all this.<br />
<br />
Suggestion: After you close this question, open a new question describing your specific database/code + asking for design suggestions.<br />
<br />
Likely you'll have some great suggestions, as there are some very smart people posting to EE.
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Simon Leung

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Enable mariadb on Centos8. It seems that I can't access to port 3306.<br />
Already enable the firewall : firewall-cmd --permanent --add-port=3306/tcp<br />
Beside, 3306 port is show as listen on Centos<br />
[root@centos8 etc]# netstat -anp | grep 3306<br />
tcp &nbsp; &nbsp; &nbsp; &nbsp;0 &nbsp; &nbsp; &nbsp;0 0.0.0.0:3306 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;0.0.0.0:* &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; LISTEN
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Enable mariadb on Centos8. It seems that I can't access to port 3306.
Already enable the firewall : firewall-cmd --permanent --add-port=3306/tcp
Beside, 3306 port is show as listen on Centos
[root@centos8 etc]# netstat -anp | grep 3306
tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN

cannot remote access to Mariadb

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