How do I lock a user account in Linux?

petulia3478

🔴 Important Note
This locks users when using passwords, pam_unix. It does not disallow SSH public key authentication access.

To lock user testuser's account:

# /usr/bin/passwd -l testuser
Locking password for user testuser.
passwd: Success

or:

# /usr/sbin/usermod -L testuser

You will see that the password field for testuser is preceeded by ! in /etc/shadow

# /bin/grep testuser /etc/shadow
testuser:!!$1$wypNKIu9$Ib3YmLexp7BVl88crX5eE/:14445:0:99999:2:::

To disable the account completely use.

$ chage -E0 testuser