How to Resolve \'mysqli_connect() expects parameter 6 to be string, resource given\' Error when Connecting to MySQL Over SSH in PHP?

Connecting to a MySQL Server Over SSH in PHP

Problem:

You've encountered an error while connecting to your database using SSH and the ssh2 library. Specifically, the error is "mysqli_connect() expects parameter 6 to be string, resource given."

Issue Explanation:

The above error message suggests that you've passed an incorrect type to the sixth parameter of the mysqli_connect function.

Solution:

To resolve the issue, pass a string instead of a resource as the sixth parameter. In your case, this parameter is expected to be the path to the SSH tunnel socket.

SSH Tunnel Setup:

To connect to a MySQL server over SSH, you'll need to set up an SSH tunnel using the following steps:

1. SSH Tunnel Command:

ssh -fNg -L 3307:10.3.1.55:3306 [email protected] 

• '-f': Run in the background
• '-N': Don't execute a remote command
• '-L': Enable local port forwarding
• '3307': Local port on your machine
• '10.3.1.55': Remote MySQL server address
• '3306': Remote MySQL server port
• '[email protected]': SSH proxy host and username

2. MySQL Client Connection:

Once the tunnel is set up, you can connect to your MySQL server using your local MySQL client:

mysql -h 127.0.0.1 -P 3307 -u dbuser -p passphrase

• '-h': Local MySQL server address
• '-P': Local port number
• '-u': MySQL username
• '-p': MySQL password

3. PHP Connection:

Finally, connect to your MySQL server in your PHP application:

<code class="php"><?php
$smysql = mysql_connect("127.0.0.1:3307", "dbuser", "passphrase");
mysql_select_db("db", $smysql); 
?></code>

Security Note:

For enhanced security, use a bastion host (Jumpbox) as the SSH proxy instead of connecting directly to your MySQL server.

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