Can't connect to remote SQL database in PHP, but remote access is set up and confirmed working

Question

I'm trying to learn to use SQL stuff in PHP but I'm having an issue simply connecting to my database.

The database is almost certainly working with remote access to some extent. I disabled iptables temporarily (I know, bad bad bad!), so there's no firewall blocking access. The MySQL user I am using is configured to be able to connect from any IP. The SQL server is listening properly to all connections and is run on a Linux dedicated server.

[root@1742CC-XEON ~]# netstat -lpnut | grep mysql
tcp        0      0 0.0.0.0:3315                0.0.0.0:*                   LISTEN      3915/mysqld

I've also used the exact same credentials to successfully remotely connect to my database in Java, like so:

        Class.forName("com.mysql.jdbc.Driver");
        Connection conn = DriverManager.getConnection("jdbc:mysql://__ip__:_port_/_dbname_", "username", "password");
        System.out.println("Connection established.");

This functions just fine, and I can successfully run queries, etc. Since I have iptables disabled at the moment this connection functions just fine anywhere that has Java and the Java SQL connector.

Now, I'm trying to connect to the same database in PHP:

        $db = mysqli_connect($sql_host, $sql_user, $sql_pass, $sql_db, $sql_port);

And this connection fails with the following error:

Warning: mysqli_connect(): (HY000/2003): Can't connect to MySQL server on 'xx.xx.xx.ip' (111)

Note that $sql_user, $sql_pass, $sql_host, etc. are all the same as the credentials used in the Java connection, so there shouldn't be any issue with the user not being able to access the server from a new IP, since that user is granted access on % and I've made sure that it is indeed able to access the SQL server from multiple IPs not explicitly allowed in the users table. I've also tried different users, including root, and all give the same connection error.

I've spent a few hours looking around but I honestly can't find anything that seems to be the right answer, would really appreciate any help!

Is it possible that this is caused by my webhost? I've tried this script on HostGator webhost as well as the whois.com hosting and both give the same error. Could they possibly be preventing the PHP script from connecting to the remote database?

Answer 1

您是否尝试过从Web主机远程登录到3315上的服务器？