Ubuntu 25.04: Quick way to allow a simple password using pam-auth-update
Use-case:
Living / bedroom room PC that only plays videos (media station).
Input is a tiny wireless keyboard (Ex: Rii Wireless Keyboard).
Typing a long, complex password is annoying; so you want something quick like aaabbb.
Ubuntu doesn’t have 4 digit PINs like Windows, so instead we have to settle for 6 digit passwords
The default Ubuntu settings require complex passwords 8 characters or longer.
- Open the PAM configuration menu Prior to running the next command which opens an interactive TUI (text UI), optionally backup /etc/pam.d/common-password.
sudo pam-auth-update --force
- In the text‑UI checklist, uncheck:
[ ] Password quality checking
Press Space to toggle, Tab to move to OK, Enter to save.
- Set your short password (e.g.,
aaabbb):
sudo passwd <your‑username> # or if already logged in passwd
- (Optional) Re‑enable the quality check later by running the same command and ticking the box again.
Your current password stays valid; the policy only affects future changes.
Security Trade-offs
| Benefit | Risk |
|---|---|
| Instant sign-in from couch-keyboard | Anyone with physical access can log in |
| No need to remember a complex string | Remote attacks stay possible if SSH is open |
| Easy to change back later | Weak sudo password if you keep the same PIN |
Minimum precautions
- Disable or firewall SSH if you don’t need it.
- Use a separate strong password for any admin account you expose to the network.
- Consider full-disk encryption so data is safe when the machine is powered off.