This bugged me for a while. I wanted to connect to a mysql server via a java app with the jdbc connector. I kept getting this error: “com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure” and then some reflection got into my stack trace. Connecting from the local machine with the mysql client worked but anything than that wouldn’t. The solution is this. You have to edit the my.ini (on windows) file or the my.cnf (on linux, usualy at /etc/mysql/my.cnf). Find the line that says “bind-address =” and change it to “bind-address =” or whatever the ip of your mysql server is. This is less secure as mysql says but it will do the trick.