SMBPASSWD(5) File Formats and Conventions SMBPASSWD(5)NAMEsmbpasswd - The Samba encrypted password file
SYNOPSISsmbpasswdDESCRIPTION
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. 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.
· 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.
· X - This means the password does not expire.
· 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. For further
information regarding the flags that are supported please refer to
the man page for the pdbedit command.
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.
SEE ALSOsmbpasswd(8), Samba(7), and the Internet RFC1321 for details on the MD4
algorithm.
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.
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.
Samba 3.0 11/20/2008 SMBPASSWD(5)
