Mysql PDO access denied for remote connection but Mysql CLI works

Question

I am trying to connect to a remote Mysql server from my web server. I followed the following steps:

On the remote server:

1. “CREATE USER ’newremoteuser’@‘web-server_ip' IDENTIFIED BY 'remote_user_password’;”
2. “GRANT ALL PRIVILEGES ON *.* TO 'newremoteuser'@'web_server_ip’;”
3. “FLUSH PRIVILEGES;”

On the web server when I try to access using Mysql CLI, the connection is successful.

"mysql -u newremoteuser -h remote_server_ip -p"

However when I try to connect to remote server using PDO or Mysqli in PHP, I get the error

"FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[28000] [1045] Access denied for user 'newremoteuser'@'my-domain-name.com' (using password: YES)'

Below is the PDO code

$REMOTEPDO = new PDO("mysql:host=$remote_server_ip;port=3306;dbname=$remote_db", $newremoteuser, $remote_user_password);
$REMOTEPDO->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

I think it is denying access to 'newremoteuser'@'my-domain-name.com' as the remote user I added was 'newremoteuser'@'web-server_ip'. However, I can not find a solution to this. Can anyone please point me in the right direction?

Note: 'my-domain-name.com' is my website name hosted on my 'web_server_ip' server.

Remote server is Ubuntu 18 and Web server is Ubuntu 14.

Answer 1

As you've pointed out, changing the host for that user might fix your problem since the connection denial seems to be because of a host mismatch. Try updating the host for your existing user from the IP address to the domain name:

UPDATE mysql.user SET Host='my-domain-name.com' WHERE User='username';
FLUSH PRIVILEGES;

If it still doesn't work, it might be worth updating the host to '%' instead and seeing if it then lets you connect.

Answer 2

I just went through this. I could connect with command line but not PDO. My webserver client wouldn't connect until I enabled httpd_can_network_connect_db on the client server's SELinux and rebooted.

sudo setsebool -P httpd_can_network_connect_db 1

I forgot the reboot and chased my tail a bit longer than necessary.