Okay, you've just seen how to have Linux automatically lock user accounts that are under attack. There will also be times when you'll want to be able to manually lock out user accounts. Let us look at the following example:

• When a user goes on vacation and you want to ensure that nobody monkeys around with that user's account while he or she is gone
• When a user is under investigation for questionable activities
• When a user leaves the company

In regard to the last point, you may be asking yourself, "Why can't we just delete the accounts of people who are no working here?" And, you certainly can, easily enough. However, before you do so, you'll need to check with your local laws to make sure that you don't get yourself into deep trouble. Here in the United States, for example, we have the Sarbanes-Oxley law, which restricts what files that publicly traded companies can delete from their computers. If you were to delete a user account, along with that user's home directory and mail spool, you just might be running afoul of Sarbanes-Oxley or whatever you may have as the equivalent law in your own home country.

Anyway, there are two utilities that you can use to temporarily lock a user account:

• Using usermod to lock a user account
• Using passwd to lock user accounts