Passwords

Your system associates a password with each account. A unique password provides some system security for your files. System use and data are valuable resources that require protection. 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 only permit the users access to certain commands or files.

This section describes the following procedures:

• Password Guidelines
• Changing Your Password (passwd Command)
• Setting Your Password to Null (passwd Command)

Password Guidelines

You should have a unique password. Passwords should not be shared. Protect passwords as 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.

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 write passwords down. However, if you must write them down, place them in a physically secure place, such as a locked cabinet.
• Do not use your user ID as a password. Do not use it reversed, doubled, or otherwise modified.
• Do not reuse passwords. The system may 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.

Changing Your Password (passwd Command)

Use the passwd command to change your password.

1. At the prompt, enter:

   passwd

   If you do not have a password, skip step 2.
2. The following prompt appears:

   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. Enter your current password.
3. The following prompt appears:

   UserID's New password:

   Enter the new password you want.
4. The following prompt appears, asking for 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 can not recreate.

Examples

1. To change the password of the user denise, enter:

   passwd

   The system displays information similar to the following:

   Changing password for "denise"
   denise's Old password:
   denise's New password:
   Enter the new password again:
   $

2. The following example enters the current password incorrectly:

   $ passwd
   Changing password for "denise"
   denise's Old password:
   Your entry does not match the old password.
   You are not authorized to change "denise's" password.
   $

3. The following example reenters the new password incorrectly:

   $ passwd
   Changing password for "denise"
   denise's Old password:
   denise's New password:
   Enter the new password again:
   The password entry does not match, please try again.
   denise's New password:
   Enter the new password again:
   $

See the passwd command in the AIX Version 4.3 Commands Reference for the exact syntax.

Setting Your Password to Null (passwd Command)

If you do not want to enter a password each time you login, set your password to null.

To set your password to NULL (blank), enter:

passwd

When 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 is displayed.

See the passwd command in theAIX Version 4.3 Commands Reference Book for more information and the exact syntax.

Related Information

Commands and Processes Overview

File and System Security

User Environment and System Information

User Environment Customization

Shells Overview

Korn or POSIX Shell

Bourne Shell

C Shell