Tribblix: manual page: smbpasswd.5

SMBPASSWD(5) File Formats and Conventions SMBPASSWD(5)

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 within 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:

+o U - This means this is a "User" account, i.e. an
ordinary user.

+o 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.

+o D - This means the account is disabled and no SMB/CIFS
logins will be allowed for this user.

+o X - This means the password does not expire.

+o 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 part of version 4.18.11 of the Samba suite.

AUTHOR