SRM Suite 3.0 binary installation

I've  installed a front-end server and a back-end server using the binaries (not the vApp).

I've edited the servers.xml on the front-end server to point to the back-end server's MySQL instance.

However I get an error message in the logs:

Caused by: java.sql.SQLException: null,  message from server: "Host 'x.x.x.x' is not allowed to connect to this MySQL server"

at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1055)

I've tried logging into the master database on the back end and adding the front-end host, but it says the apg user doesn't have the privileges.

Is there a step I'm missing?

I don't want to use the vApp installation.  Pretend these are physical hosts.