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5.3.2.3 Password Hashing in MySQL »
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5.3.2.2. End-User Guidelines for Password Security

MySQL users should use the following guidelines to keep passwords secure.

When you run a client program to connect to the MySQL server, it is inadvisable to specify your password in a way that exposes it to discovery by other users. The methods you can use to specify your password when you run client programs are listed here, along with an assessment of the risks of each method. In short, the safest methods are to have the client program prompt for the password or to specify the password in a properly protected option file.

  • Use a -pyour_pass or --password=your_pass option on the command line. For example: 

    shell> mysql -u francis -pfrank db_name

    This is convenient but insecure, because your password becomes visible to system status programs such as ps that may be invoked by other users to display command lines. MySQL clients typically overwrite the command-line password argument with zeros during their initialization sequence. However, there is still a brief interval during which the value is visible. Also, on some systems this overwriting strategy is ineffective and the password remains visible to ps. (SystemV Unix systems and perhaps others are subject to this problem.)

    If your operating environment is set up to display your current command in the title bar of your terminal window, the password remains visible as long as the command is running, even if the command has scrolled out of view in the window content area.

  • Use the -p or --password option on the command line with no password value specified. In this case, the client program solicits the password interactively: 

    shell> mysql -u francis -p db_name
Enter password: ********

    The “*” characters indicate where you enter your password. The password is not displayed as you enter it.

    It is more secure to enter your password this way than to specify it on the command line because it is not visible to other users. However, this method of entering a password is suitable only for programs that you run interactively. If you want to invoke a client from a script that runs noninteractively, there is no opportunity to enter the password from the keyboard. On some systems, you may even find that the first line of your script is read and interpreted (incorrectly) as your password.

  • Store your password in an option file. For example, on Unix you can list your password in the [client] section of the .my.cnf file in your home directory: 

    [client]
password=your_pass

    To keep the password safe, the file should not be accessible to anyone but yourself. To ensure this, set the file access mode to 400 or 600. For example: 

    shell> chmod 600 .my.cnf

    Section 4.2.3.3, “Using Option Files”, discusses option files in more detail.

  • Store your password in the MYSQL_PWD environment variable. See Section 2.14, “Environment Variables”.

    This method of specifying your MySQL password must be considered extremely insecure and should not be used. Some versions of ps include an option to display the environment of running processes. If you set MYSQL_PWD, your password is exposed to any other user who runs ps. Even on systems without such a version of ps, it is unwise to assume that there are no other methods by which users can examine process environments.

On Unix, the mysql client writes a record of executed statements to a history file (see Section 4.5.1, “mysql — The MySQL Command-Line Tool”). By default, this file is named .mysql_history and is created in your home directory. Passwords can appear as plain text in SQL statements such as CREATE USER, GRANT, and SET PASSWORD, so if you use these statements, they are logged in the history file. To keep this file safe, use a restrictive access mode, the same way as described earlier for the .my.cnf file.

If your command interpreter is configured to maintain a history, any file in which the commands are saved will contain MySQL passwords entered on the command line. For example, bash uses ~/.bash_history. Any such file should had a restrictive access mode.


User Comments

Posted by Stephane Chazelas on March 31 2009 2:14pm[Delete] [Edit]

It seems this page doesn't cover how to call the mysql commands in scripts without passing the password in clear. One solution could be to use expect with mysql -u user -p, but a much better solution using an undocumented mysql option: --defaults-file.

With a POSIX/Bourne like shell:

{ printf '[client]\npassword=%s\n' xxxx |
3<&0 <&4 4<&- mysql --defaults-file=/dev/fd/3 -u myuser
} 4<&0

The password is then passed using a pipe between your shell and the mysql command.

Or with ksh93, zsh or bash and some implementations of ksh88:

mysql --defaults-file <(
printf '[client]\npassword=%s\n' xxxx
) -u myuser

If "printf" is not built in your shell, you can use echo instead but beware of backslashes, you you can use an here-file or here-string.

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