smbpasswd

Name

smbpasswd — The Samba encrypted password file

Synopsis

smbpasswd

DESCRIPTION

This tool is part of the Samba(7) suite.

smbpasswd is the Samba encrypted password file. It contains - the username, Unix user id and the SMB hashed passwords of the - user, as well as account flag information and the time the - password was last changed. This file format has been evolving with - Samba and has had several different formats in the past.

FILE FORMAT

The format of the smbpasswd file used by Samba 2.2 - is very similar to the familiar Unix passwd(5) - file. It is an ASCII file containing one line for each user. Each field - ithin each line is separated from the next by a colon. Any entry - beginning with '#' is ignored. The smbpasswd file contains the - following information for each user:

name

This is the user name. It must be a name that - already exists in the standard UNIX passwd file.

uid

This is the UNIX uid. It must match the uid - field for the same user entry in the standard UNIX passwd file. - If this does not match then Samba will refuse to recognize - this smbpasswd file entry as being valid for a user. -

Lanman Password Hash

This is the LANMAN hash of the user's password, - encoded as 32 hex digits. The LANMAN hash is created by DES - encrypting a well known string with the user's password as the - DES key. This is the same password used by Windows 95/98 machines. - Note that this password hash is regarded as weak as it is - vulnerable to dictionary attacks and if two users choose the - same password this entry will be identical (i.e. the password - is not "salted" as the UNIX password is). If the user has a - null password this field will contain the characters "NO PASSWORD" - as the start of the hex string. If the hex string is equal to - 32 'X' characters then the user's account is marked as - disabled and the user will not be able to - log onto the Samba server.

WARNING !! Note that, due to - the challenge-response nature of the SMB/CIFS authentication - protocol, anyone with a knowledge of this password hash will - be able to impersonate the user on the network. For this - reason these hashes are known as plain text - equivalents and must NOT be made - available to anyone but the root user. To protect these passwords - the smbpasswd file is placed in a directory with read and - traverse access only to the root user and the smbpasswd file - itself must be set to be read/write only by root, with no - other access.

NT Password Hash

This is the Windows NT hash of the user's - password, encoded as 32 hex digits. The Windows NT hash is - created by taking the user's password as represented in - 16-bit, little-endian UNICODE and then applying the MD4 - (internet rfc1321) hashing algorithm to it.

This password hash is considered more secure than - the LANMAN Password Hash as it preserves the case of the - password and uses a much higher quality hashing algorithm. - However, it is still the case that if two users choose the same - password this entry will be identical (i.e. the password is - not "salted" as the UNIX password is).

WARNING !!. Note that, due to - the challenge-response nature of the SMB/CIFS authentication - protocol, anyone with a knowledge of this password hash will - be able to impersonate the user on the network. For this - reason these hashes are known as plain text - equivalents and must NOT be made - available to anyone but the root user. To protect these passwords - the smbpasswd file is placed in a directory with read and - traverse access only to the root user and the smbpasswd file - itself must be set to be read/write only by root, with no - other access.

Account Flags

This section contains flags that describe - the attributes of the users account. In the Samba 2.2 release - this field is bracketed by '[' and ']' characters and is always - 13 characters in length (including the '[' and ']' characters). - The contents of this field may be any of the following characters: -

U - This means - this is a "User" account, i.e. an ordinary user. Only User - and Workstation Trust accounts are currently supported - in the smbpasswd file.
N - This means the - account has no password (the passwords in the fields LANMAN - Password Hash and NT Password Hash are ignored). Note that this - will only allow users to log on with no password if the - null passwords parameter is set in the - smb.conf(5) config file.
D - This means the account - is disabled and no SMB/CIFS logins will be allowed for this user.
W - This means this account - is a "Workstation Trust" account. This kind of account is used - in the Samba PDC code stream to allow Windows NT Workstations - and Servers to join a Domain hosted by a Samba PDC.

Other flags may be added as the code is extended in future. - The rest of this field space is filled in with spaces.

Last Change Time

This field consists of the time the account was - last modified. It consists of the characters 'LCT-' (standing for - "Last Change Time") followed by a numeric encoding of the UNIX time - in seconds since the epoch (1970) that the last change was made. -

All other colon separated fields are ignored at this time.

VERSION

This man page is correct for version 3.0 of - the Samba suite.

AUTHOR

The original Samba software and related utilities - were created by Andrew Tridgell. Samba is now developed - by the Samba Team as an Open Source project similar - to the way the Linux kernel is developed.