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Christian
Asked: 2014-02-28 02:37:36 +0800 CST

monit mysql server blocked because of too many bad connections

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Is there any tweak for monit or another way to monitor whether one server can access mysql on another server?

I tried it with monit but as you probably know, after 10 attempts, mysql blocks the server.

check host db1.server with address db1.server
   if failed port 3306 protocol mysql then alert

.

mysqli: host <host> is blocked because of many connection errors; unblock with mysqladmin flush-hosts
mysql

1 Answers

  1. Edit (total new answer)

    I have Googled a bit about this issue and found some clue :

    Seems that MySql does not really like when :

    • a connection is made on port 3306 without authentication
    • a socket is openened and then dropped without any SQL handshaking

    So, a workaround could be to perform a real MySql connection and run a query.

    Here is a way to do it. You will need to install mysql-client on the monitoring server and grant correct access on MySql server.

    Monit check setup :

    check program mysql with path "/root/mysql_check.sh"
  if status != 0 then alert

    Script mysql_check.sh :

    #!/bin/sh
mysql -u<user> -p<password> --host=xx.xx.xx.xx <<END
SHOW VARIABLES LIKE "%version%";
END

    Script mysql_check.sh should also be valid for a custom Nagios check.

    I have tested this successfully (means can run the query remotely), but as far as i cannot reproduce the blocked host issue on my MySql 5.5 server i cannot tell if this actually solves the issue.

    Give it a try and tell me what the result is.

    My references :

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