smbpasswd

Change the current user's SMB password

$ smbpasswd

$ sudo smbpasswd -a [username]

$ sudo smbpasswd [username]

$ sudo smbpasswd -x [username]

smbpasswd [options] [username]

General usage includes a combination of action flags and optional configuration settings:
smbpasswd [-a | -d | -e | -x | -m] [-n | -p] [-U username] [-D debuglevel] [-l logfile] [-s smb_file] [-c configfile] [username]

-a
    Adds a new user to the Samba password database. The user must typically already exist as a system user.

-d
    Disables a user's Samba account, preventing them from authenticating against Samba services.

-e
    Enables a user's Samba account, allowing them to authenticate against Samba services.

-x
    Deletes a user's account from the Samba password database. This does not remove the system user.

-m
    Treats the specified account as a machine account. This is used for adding or managing entries for client machines joining a Samba domain.

-n
    Sets the specified user's password to null (empty). This can pose a significant security risk and should be used with extreme caution.

-p
    Enables 'pipe mode', causing smbpasswd to read the new password from standard input. This is useful for scripting password changes securely.

-U username
    Specifies the username on which the operation should be performed. If omitted, the current system user's Samba account is targeted.

-D debuglevel
    Sets the debug level for the command's output. Higher numbers (0-10) produce more verbose logging for troubleshooting.

-l logfile
    Specifies the path to the log file where debug messages and operational information will be written.

-s smb_file
    Specifies an alternative smb.conf file to use instead of the default location. This can be useful for testing or specific configurations.

-c configfile
    Specifies the path to the Samba configuration file. This option is equivalent to -s.

-h
    Displays a brief help message with command usage and available options, then exits.

smbpasswd is a command-line utility provided by the Samba suite, essential for administering user and machine accounts within a Samba environment. Its primary function is to manage passwords stored in Samba's various authentication backends, such as tdbsam, ldapsam, or the legacy smbpasswd file.

Administrators use smbpasswd to add new users, delete existing accounts, enable or disable user access, and change passwords for users who need to access Samba shares, printers, or other services. Importantly, smbpasswd operates independently of the system's standard passwd command, meaning it manages passwords specifically for Samba's internal authentication system. It's a critical tool for ensuring seamless integration and authentication for Windows clients connecting to Linux/Unix servers running Samba.

Using smbpasswd to modify the Samba password database typically requires root privileges. It is crucial to understand that password changes made via smbpasswd generally do not synchronize with the user's system login password (stored in /etc/shadow). Therefore, a user might have different passwords for logging into the Linux system and accessing Samba shares. The actual password backend smbpasswd interacts with is determined by the passdb backend setting in your smb.conf file. Incorrect usage, especially with the -n option or improper handling in scripts, can introduce significant security vulnerabilities.

smbpasswd primarily operates on Samba's internal password databases (e.g., tdbsam, ldapsam, or the traditional smbpasswd file). It does not manage passwords if your Samba configuration uses external authentication without a local Samba database, such as direct authentication against NIS, Winbind with Active Directory (without a local SAM), or if unix password sync = yes is configured to strictly rely on system passwords.

When automating password changes using smbpasswd, it is critical to implement secure practices. Avoid passing passwords directly on the command line as they can be visible in process listings. Instead, utilize the -p (pipe mode) option, piping the password securely from a script or another command (e.g., echo "new_password" | smbpasswd -s username). Ensure that scripts handling passwords have appropriate file permissions and are only accessible by authorized personnel.

smbpasswd has been a fundamental utility within the Samba suite since its inception in the early 1990s. As Samba aimed to provide seamless file and print services compatible with Microsoft Windows on Unix-like operating systems, a dedicated method for managing user authentication was essential. Initially, smbpasswd was used to manage passwords in a simple flat-file database. With the evolution of Samba to support more sophisticated authentication backends, such as tdbsam (a TDB database) and ldapsam (for integration with LDAP or Active Directory), smbpasswd adapted to provide a consistent command-line interface across these different storage mechanisms. Its core function of managing local Samba user identities has remained central throughout its development.

smbd(8), nmbd(8), samba(7), pdbedit(8), passwd(1)