How to know about MySQL 'refused connections'

Question

Hello,

I am using MONyog to montitor my two mysql servers. I get alert emails from MONyog when something goes wrong. There is an error I could not find out why. It says:

Connection History: Percentage of refused connections) - 66.67%

the percentage is not important, this is just about having refused connections. I get this email every half an hour. So this is like a constant situation. This must be my mistake, because I just set up those servers and there is no chance somebody else could be interfering the servers.

MONyog advices me:

1. Try to isolate users/applications that are using an incorrect password or trying to connect from unauthorized hosts.
2. A client will be disallowed to connect if it takes more than connect_timeout seconds to connect.
3. Set the value of log_warnings system variable to 2. This will force the MySQL server to log further information about the error.

I added log_warnings=2 to my.cnf and I enabled logging like this:

[mysqld_safe]
.
.
log_warnings=2
log-error = /var/log/mysql/error.log
.
.
.
.
[mysqld_safe]
.
log-error=/var/log/mysqld.log
.
.

I cannot see any warnings at /var/log/mysql/error.log I can see some warnings at /var/log/mysqld.log but they are about something else.

In sum, my question is how can I detect refused connections? Please let me know if any more info is required.

Thanks in advance.