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3.1 Logging in

3.1.2 Passwords

When your account is issued, you will be given an initial password. It is important for system and personal security that the password for your account be changed to something of your choosing. The command for changing a password is "passwd". You will be asked both for your old password and to type your new selected password twice. If you mistype your old password or do not type your new password the same way twice, the system will indicate that the password has not been changed.

Some system administrators have installed programs that check for appropriateness of password (is it cryptic enough for reasonable system security). A password change may be rejected by this program.

When choosing a password, it is important that it be something that could not be guessed -- either by somebody unknown to you trying to break in, or by an acquaintance who knows you. Suggestions for choosing and using a password follow:

Don't use a word (or words) in any language

use a proper name

use information that can be found in your wallet

use information commonly known about you (car license, pet name, etc)

use control characters. Some systems can't handle them

write your password anywhere

ever give your password to *anybody*

Do use a mixture of character types (alphabetic, numeric, special)

use a mixture of upper case and lower case

use at least 6 characters

choose a password you can remember

change your password often

make sure nobody is looking over your shoulder when you are entering your password

Introduction to Unix - 14 AUG 1996
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