We are unable to install MySQL Server v 7 or v8 on CentOS server with required environment.
Our install make MySQL server works in no network /local mode on port 0 only
1.
CentOS often has SELinux enabled by default, which can block access to non-standard services or ports if the appropriate security context is not configured.
2.
MySQL 7 does not exist: after version 5.7 comes version 8: en.wikipedia.org/wiki/MySQL#Release_history
If your administrator claims to have installed «MySQL 7» — this is a sure sign of his incompetence.
3.
If MySQL cannot open a socket or bind to a TCP port — for example, because the mysql user does not have sufficient privileges or because another service is using port 3306 — the server may fall back to port = 0.
This typically happens if the MySQL user does not have sufficient privileges or if the port is already being used by another process.
4.
You may have a wrongly configured bind-address: dev.mysql.com/doc/refman/8.4/en/server-system-variables.html#sysvar_bind_address
5.
A firewall (such as firewalld, iptables, or UFW) may not allow external connections on port 3306, even though MySQL is listening on that port.
6.
You may have the skip_networking option enabled: dev.mysql.com/doc/refman/8.4/en/server-system-variables.html#sysvar_skip_networking
7.
Sometimes MariaDB is installed by default on CentOS, and if you try to install MySQL on top of it or mix their repositories, there may be package conflicts.
8.
The MySQL user account you are using may not have the necessary privileges to connect from the required host (for example, % for any host or a specific IP).