MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
If the following error occurs, it means that mysqld has received many connection requests from the given host that were interrupted in the middle:
Host 'host_name' is blocked because of many connection errors.
Unblock with 'mysqladmin flush-hosts'
The value of the
max_connect_errors system
variable determines how many successive interrupted connection
requests are permitted. (See
Section 5.1.7, “Server System Variables”.) After
max_connect_errors failed
requests without a successful connection,
mysqld assumes that something is wrong (for
example, that someone is trying to break in), and blocks the
host from further connections until you issue a
FLUSH HOSTS statement or
execute a mysqladmin flush-hosts command.
By default, mysqld blocks a host after 100
connection errors. You can adjust the value by setting
max_connect_errors at server
startup:
shell> mysqld_safe --max_connect_errors=10000 &The value can also be set at runtime:
mysql> SET GLOBAL max_connect_errors=10000;
If you get the Host
'
error message for a given host, you should first verify that
there is nothing wrong with TCP/IP connections from that host.
If you are having network problems, it does you no good to
increase the value of the
host_name' is blockedmax_connect_errors variable.
w/ 2GB of RAM. When I set max_connections
parameter to 1000, connection time takes too
much. Keep it as low as you can
I also think the default setting of 10 is a bit low, 1000 would be more likely..
We were not seeing any errors in the mysqld.log that led us to determine that our nagios check was the cause; luckily we realized it eventually.
http://dev.mysql.com/doc/mysql/en/Communication_errors.html
the mysql.err logfile. If you rotate that away all further messages will never show up as flush-logs does not reopen stderr!
(This does not apply to Debian Sarge and newer versions as they are patched to log error messages to syslog via a pipe to "logger")
http://bugs.mysql.com/bug.php?id=24761
I was looking for a way to block hosts (for sometime) based on authentication failure counts (i.e. block bad attempts for a few minutes/hours and release automatically).
About a year ago I wrote something to block hackers to my SIP server which has proved successful.
Hence, I adapted it to MySQL.
The code/explanation is at http://www.abelcanada.com/securemysql.php for anybody who it interested.
This model can be adapted for any software which is used for IP (or any other) login and parameters can be changed to suite each individual requirement.
This complements IPTABLES, but is a better solution as it blocks the IP as a service, rather than global.
Anthonus