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smbpasswd — The Samba encrypted password file
smbpasswd
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.
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:
This is the user name. It must be a name that already exists in the standard UNIX passwd file.
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.
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.
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.
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.
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.
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.
The original Samba man pages were written by Karl Auer. The man page sources were converted to YODL format (another excellent piece of Open Source software, available at ftp://ftp.icce.rug.nl/pub/unix/) and updated for the Samba 2.0 release by Jeremy Allison. The conversion to DocBook for Samba 2.2 was done by Gerald Carter. The conversion to DocBook XML 4.2 for Samba 3.0 was done by Alexander Bokovoy.