PHP Cookbook

14.1. Keeping Passwords Out of Your Site Files

Problem

You need to use a password to connect to a database, for example. You don’t want to put the password in the PHP files you use on your site in case those files are compromised.

Solution

Store the password in an environment variable in a file that the web server loads when starting up; then, just reference the environment variable in your script:

mysql_connect('localhost',$_SERVER['MYSQL_USER'],$_SERVER['MYSQL_PASSWORD']);

Discussion

While this technique removes passwords from the source code of your pages, it does make them available in other places that need to be protected. Most importantly, make sure that there are no publicly viewable pages that call phpinfo( ) . Because phpinfo( ) displays environment variables available to scripts, it displays the passwords put into environment variables.

Next, especially if you are in a shared hosting setup, make sure that the environment variables are set in such a way that they are available only to your virtual host, not to all shared hosting users. With Apache, you can do this by setting the variables in a separate file from the main configuration file:

SetEnv  MYSQL_USER     "susannah"
SetEnv  MYSQL_PASSWORD "y23a!t@ce8"

Inside the <VirtualHost> directive for the site in the main configuration file, include this separate file as follows:

Include "/usr/local/apache/database-passwords"

Make sure that the separate file that contains the passwords (e.g., /usr/local/apache/database-passwords