System User's Guide: Operating System and Devices

Passwords

Your system associates a password with each account. A unique password provides some system security for your files. Security is an important part of computer systems because it keeps unauthorized people from gaining access to the system and from tampering with other users' files. Security can also allow some users exclusive privileges to which commands they can use and which files they can access. For protection, some system administrators permit the users access only to certain commands or files.

This section describes the following procedures:

Password Guidelines

You should have a unique password. Passwords should not be shared. Protect passwords as you would any other company asset. When creating passwords, make sure they are difficult to guess, but not so difficult that you have to write them down to remember them.

Using obscure passwords keeps your user ID secure. Passwords based on personal information, such as your name or birthday, are poor passwords. Even common words can be easily guessed.

Good passwords have at least six characters and include nonalphabetic characters. Strange word combinations and words purposely misspelled are also good choices.

Note: If your password is so hard to remember that you have to write it down, it is not a good password.

Use the following guidelines when selecting a password:

Do not use your user ID as a password. Do not use it reversed, doubled, or otherwise modified.
Do not reuse passwords. The system might be set up to deny the reuse of passwords.
Do not use any person's name as your password.
Do not use words that can be found in the online spelling-check dictionary as your password.
Do not use passwords shorter than six characters.
Do not use obscene words; they are some of the first ones checked when guessing passwords.
Do use passwords that are easy to remember, so you won't have to write them down.
Do use passwords that use both letters and numbers and that have both lowercase and uppercase letters.
Do use two words, separated by a number, as a password.
Do use pronounceable passwords. They are easier to remember.
Do not write passwords down. However, if you must write them down, place them in a physically secure place, such as a locked cabinet.

Changing Passwords (passwd Command)

To change your password, use the passwd command.

At the prompt, type:
```
passwd
```
If you do not already have a password, skip step 2.
The following prompt displays:
```
Changing password for UserID
UserID's Old password:
```
This request keeps an unauthorized user from changing your password while you are away from your system. Type your current password and press Enter.
The following prompt displays:
```
UserID's New password:
```
Type the new password you want and press Enter.
The following prompt displays, asking you to reenter your new password.
```
Enter the new password again:
```
This request protects you from setting your password to a mistyped string that you cannot re-create.

See the passwd command in the AIX 5L Version 5.2 Commands Reference for the complete syntax.

Setting Passwords to Null (passwd Command)

If you do not want to enter a password each time you log in, set your password to null (blank).

To set your password to null, type:

passwd

When you are prompted for the new password, press Enter or Ctrl-D.

The passwd command does not prompt again for a password entry. A message verifying the null password displays.

See the passwd command in the AIX 5L Version 5.2 Commands Reference Book for more information and the exact syntax.