How do I make my forum safer against hacker attacks

Keep your SMF version up to date and be on the lookout for security updates. In addition to keeping up with security updates and making sure your SMF version is up to date you can follow these steps:

Change your passwords often, and make sure you have different passwords for your:

 * FTP
 * Database user (MySQL, PostgreSQL, or SQLite)
 * PhpMyAdmin
 * Your forum administrator account
 * The most important password is the database access password (which is usually used to access PhpMyAdmin, or another database management script such as Eskuel). This password is stored in the Settings.php file, and you should make sure this is not the same password you use for your FTP or your forum administrator account.
 * Make sure your passwords are difficult to guess. You can do this by making sure your passwords do not relate to you (i.e. your spouses name), by mixing capital and lowercase letters with numbers, and by using special characters where applicable.
 * Frequently backup your forum database and FTP files, and make sure you understand how to restore these backups (see the available FAQ's about that step).
 * Delete Temporary files such as install.php, converters, recovery tools, etc.
 * Delete any login failures made by administrators from the error log.
 * Do not allow guests to upload anything.
 * Do not allow .exe or Flash files to be uploaded or displayed.