How To Check Password Strength With Cracklib-check Command

[jibinw]

Creating a strong and unique password for Linux or Unix-like systems

• Create a password with mix of numbers, special symbols, and alphabets.
• Make sure your password is hard to guess. You can use tool such as makepasswd to create hard to guess password.
• Do not use simple words like “password”, “123456”, “123abc” or “qwerty”.
• Use a unique password for all your server accounts.
• A minimum password length of 12 to 14 characters should be used. See how to configure CentOS / RHEL / Fedora Linux based server password quality requirements.
• Generating passwords randomly where feasible. You can do this with a simple shell script function.
• If possible use two-factor authentication.
• Use pam_crack to ensure strong passwords and to check passwords against a dictionary attack.

But, how do you test the effectiveness of a password in resisting guessing and brute-force attacks under Linux? The answer is simple use cracklib-check command.

Code: [Select]

[b]Install cracklib on a Linux based system[/b]
Type the following yum command to install on RHEL and friends:

Code: [Select]

# yum install cracklib[/size]

Type the following apt-get command to install on Debian/Ubuntu and friends:

Code: [Select]

# apt-get install libcrack2
Examples

Test a simple password like “password”, enter:

Code: [Select]

$ echo "password" | cracklib-check
Sample outputs:

password: it is based on a dictionary word

Try sequential patterns such as “abc123456”:

Code: [Select]

$ echo "abc123456" | cracklib-check
Sample outputs:

abc123456: it is too simplistic/systematic

Try a password with a mix of letters, numbers, and symbols:

Code: [Select]

$ echo 'i1oVe|DiZza' | cracklib-check
Sample outputs:

i1oVe|DiZza: OK

Regards..