Gfilui

I just keep verbatim the instructions in MariaDB docs but it does not work at all, and I wast a great ammount of time.

MariaDB docs does not take into account this version in its documentation.

Following the instructions i modified the file my.cnf that in my case it was /etc/mysql/my.cnf

I comment this out as the example, but in my case I had to add it manually.

 [mysqld]
 ...
 #skip-networking
 ...
 #bind-address = <some ip-address>
 ...

And as I already have an account with remote permissions, I just restarted the mysql service but nothing happened.

Check if por is open

sudo nmap -PN -p 3306 -sV server_ip

The port wasn't listening from remote ips.

English
The answer was already in the file my.cnf where it explains the configuration order so that the last file is the one that applies.
The problem I got is that the MariaDB docs recommends to comment out the lines skip-networking and bind-address.
In my case, to comment out lines does nothing, it doesn't override the previous configuration, because it only applies if it defines something new, so I had to go to the source where it was defined that keywords to comment that out in the first place.

I had to comment out this file /etc/mysql/mariadb.conf.d/50-server.cnf where it was firstly defined skip-networking and bind-address.

/etc/mysql/my.cnf

# The MariaDB configuration file
#
# The MariaDB/MySQL tools read configuration files in the following order:
# 1. "/etc/mysql/mariadb.cnf" (this file) to set global defaults,
# 2. "/etc/mysql/conf.d/*.cnf" to set global options.
# 3. "/etc/mysql/mariadb.conf.d/*.cnf" to set MariaDB-only options.
# 4. "~/.my.cnf" to set user-specific options.
#
# If the same option is defined multiple times, the last one will apply.
...

I hope this could save time to someone else.