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10 Newer Entries Showing entries 61 to 70 of 73 3 Older Entries

Displaying posts with tag: configuration (reset)

MySQL security: data integrity issues
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MySQL’s security model is not as elaborate as other popular databases. It’s missing quite a lot.

I wish to point out what I think are some very disturbing security holes, which may affect the database integrity.

This post is not about Roles, Kerberos, IPs and such. It’s about simple MySQL features, which allow common, unprivileged users, to break data integrity by using unprotected session variables.

I will consider three such issues.

We will assume a database with two tables, and two users.

GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION;
GRANT SELECT, INSERT, UPDATE, DELETE ON `w2`.* TO 'w2user'@'%';

We have one ‘root’ user, and one very simple ‘w2user’, which can’t be accused of having too many privileges. The schema, with some sample

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Do we need sql_mode?
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sql_mode must be one of the most elusive issues in setting up a MySQL database. It is also responsible for difficulties in migration, upgrading and securing of databases.

MySQL usually has little issues with migrating database from one machine to another, one version to another, one OS to another, one architecture to another. If we’re not sure, we can always migrate using mysqldump’s logical dump, right?

Not entirely right. The elusive sql_mode (empty by default) may affect out backup+restore, may affect our application behavior, may affect our data integrity.

  • Did we remember to set NO_AUTO_CREATE_USER? Oh dear, we have some users without passwords.
  • Did we remember to set NO_AUTO_VALUE_ON_ZERO? Oh dear, we’ve dumped our database for backup, restored, but AUTO_INCREMENT values
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MySQL Cluster Sandbox - test cluster to cluster replication!
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If you have max 15 minutes and want to try out MySQL Replication (geo redundancy) between two Clusters on your localhost (only tested on Linux) or on vmware then this Sandbox is for you.

Here is what you have to do:
  • Go to www.severalnines.com/sandbox
  • Create a master cluster:
    I have used the ports 1186 (for the management server) and 3306 and 3307 for the mysql servers).
  • Enter the email address and a set of scripts to install cluster will be sent.
  • Create a slave cluster:
    Make sure you use





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    cmon 0.12 - with diskdata support and a lot of fixes
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    cmon 0.12 is now released and can be downloaded from www.severalnines.com/cmon.

    Release notes:
    • connection handling - cmon will now retry connects forever. cmon will also recover and automatically reconnect to cluster after a cluster failure or if the connection to the mysql server crashes where cmon logs information. This means you will have to terminate the cmon using e.g 'killall cmon' or /etc/init.d/cmon stop
    • disk data - cmon now gathers information about the amount of table space used and this is presented in the web interface
    • init.d scripts - fixed bugs in creating the init.d scripts during make install-extra
    • fixed compiler warnings - now 0 compiler warnings on Linux systems
    • mysql_statistics table - now explicitly using engine=myisam
    • web




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    Disk data - a summary
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    Here is a summary about Disk Data tables in MySQL Cluster.

    Data node configuration:
    • SharedGlobalMemory=384M
      RAM from the shared global memory is used for the UNDO_BUFFER when you create the log file group.
      In the configuration generated by severalnines.com/config then you have to uncomment the SharedGlobalMemory in mysqlcluster-63/cluster/config/config.ini before you start the cluster.
    • DiskPageBufferMemory=3072MB
      If you are relying a lot on the disk data, we recommend to set this to as much as possible.
      In the configuration generated by severalnines.com/config then you have to uncomment the DiskPageBufferMemory in mysqlcluster-63/cluster/config/config.ini before you start the







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    Dangers of skip-grant-tables
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    When MySQL’s root password is lost and must be reset, there are two popular ways to create a new password. One of the options is far too popular, in my opinion.

    The preferred way of setting a root’s password is by using an init-file. The process for doing this is well explained in MySQL’s manual. Using this method requires creating a simple text file, in which the required

    GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFY BY '****' WIth GRANT OPTION;

    (or, alternatively,  SET PASSWORD …) statement is written.

    An entry must be written to my.cnf, or supplied via command line parameters:

    init-file=/tmp/my-init-file.sql

    MySQL must then be restarted. Upon restart, and before

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    MySQL parameters & configuration sample file
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    The following is a sample my.cnf configuration file. It includes some common and uncommon parameters, along with occasional comments. You can use this file, and tune as appropriate for your machine, operating system, and application needs. In particular, note the high values set for the InnoDB related parameters, below, and change them to match your system and [...]
    Why is MSNBot ignoring robots.txt?
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    Today, the root file system on our public svn server nearly ran out of disk space. The reason? The /tmp directory was quickly filling up with temporary files created by websvn, which I set up parallel to the FishEye repository browser for testing purposes. A quick investigation of the apache log files revealed the culprit - a crawler from Microsoft was running haywire and decided to ignore the rules in the robots.txt file, even though it did actually looked at the file before!

    Here is how robots.txt looked like (I now changed it to disallow everything):

    User-agent: *
    Disallow: /fisheye/
    Disallow: /websvn/

    If I am not mistaken, no crawler should actually consider going into the SVN browser directories. Some snippets from



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    Running Drupal 6 on MySQL 6 using the Falcon Storage Engine
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    This article describes how to install the Drupal 6.2 CMS on MySQL (http://mysql.com/) 6.0, using the Falcon Storage Engine. The operating system is a default Ubuntu 8.04 "Hardy Heron" (x86) installation.

    I will make a few assumptions here, in order to keep the instructions simple: a fresh OS install, no other MySQL databases or web services are running or have already been installed. Both MySQL and the web server are installed on the same host. You should be able to become root to install packages and to have access to the local file system and

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    Why MySQL says the server is not configured as a slave
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    Is MySQL giving you the error message "ERROR 1200 (HY000): The server is not configured as slave; fix in config file or with CHANGE MASTER TO" when you try to run START SLAVE? There are a few simple troubleshooting steps to take, but I always forget what to do. This article is to help me remember in the future!

    10 Newer Entries Showing entries 61 to 70 of 73 3 Older Entries

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