Bypassing BAD PASSWORD: contains the user name

This post covers how to work around the BAD PASSWORD: The password contains the user name in some form error that prevents you from setting the desired password on Linux (Ubuntu).

[01] Situation

• On Linux (Ubuntu), when entering a password you hit BAD PASSWORD: The password contains the user name in some form and cannot set the desired password
• ex) Test server
  • username: testuser
  • password: testuser

[02] Disabling the Validation

Modifying this is not recommended in security-sensitive environments.

2-1. Locate the Password Configuration File

On Debian (Ubuntu), /etc/pam.d/common-password references the pam_pwquality.so configuration.

# requires root
# /etc/pam.d/common-password
# here are the per-package modules (the "Primary" block)
password        requisite                       pam_pwquality.so retry=3
password        [success=2 default=ignore]      pam_unix.so obscure use_authtok try_first_pass yescrypt

2-2. Change the Password Validation Setting

In /etc/security/pwquality.conf, change to usercheck = 0.

# requires root
# /etc/security/pwquality.conf
# Whether to check if it contains the user name in some form.
# The check is enabled if the value is not 0.
usercheck = 0
#

Reference: Password validation settings reference