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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook V4.1//EN">
<refentry id="smbpasswd">
<refmeta>
<refentrytitle>smbpasswd</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>smbpasswd</refname>
<refpurpose>The Samba encrypted password file</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename>smbpasswd</filename></para>
</refsynopsisdiv>
<refsect1>
<title>DESCRIPTION</title>
<para>This tool is part of the <ulink url="samba.7.html">
Samba</ulink> suite.</para>
<para>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. </para>
</refsect1>
<refsect1>
<title>FILE FORMAT</title>
<para>The format of the smbpasswd file used by Samba 2.2
is very similar to the familiar Unix <filename>passwd(5)</filename>
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: </para>
<variablelist>
<varlistentry>
<term>name</term>
<listitem><para> This is the user name. It must be a name that
already exists in the standard UNIX passwd file. </para>
</listitem>
</varlistentry>
<varlistentry>
<term>uid</term>
<listitem><para>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.
</para></listitem>
</varlistentry>
<varlistentry>
<term>Lanman Password Hash</term>
<listitem><para>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
<constant>disabled</constant> and the user will not be able to
log onto the Samba server. </para>
<para><emphasis>WARNING !!</emphasis> 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 <emphasis>plain text
equivalents</emphasis> and must <emphasis>NOT</emphasis> 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. </para></listitem>
</varlistentry>
<varlistentry>
<term>NT Password Hash</term>
<listitem><para>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. </para>
<para>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). </para>
<para><emphasis>WARNING !!</emphasis>. 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 <emphasis>plain text
equivalents</emphasis> and must <emphasis>NOT</emphasis> 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. </para></listitem>
</varlistentry>
<varlistentry>
<term>Account Flags</term>
<listitem><para>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 characters.
</para>
<itemizedlist>
<listitem><para><emphasis>U</emphasis> - 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. </para></listitem>
<listitem><para><emphasis>N</emphasis> - 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 <parameter>
null passwords</parameter> parameter is set in the <ulink
url="smb.conf.5.html#NULLPASSWORDS"><filename>smb.conf(5)
</filename></ulink> config file. </para></listitem>
<listitem><para><emphasis>D</emphasis> - This means the account
is disabled and no SMB/CIFS logins will be allowed for
this user. </para></listitem>
<listitem><para><emphasis>W</emphasis> - 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. </para>
</listitem>
</itemizedlist>
<para>Other flags may be added as the code is extended in future.
The rest of this field space is filled in with spaces. </para>
</listitem>
</varlistentry>
<varlistentry>
<term>Last Change Time</term>
<listitem><para>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.
</para></listitem>
</varlistentry>
</variablelist>
<para>All other colon separated fields are ignored at this time.</para>
</refsect1>
<refsect1>
<title>VERSION</title>
<para>This man page is correct for version 3.0 of
the Samba suite.</para>
</refsect1>
<refsect1>
<title>SEE ALSO</title>
<para><ulink url="smbpasswd.8.html"><command>smbpasswd(8)</command></ulink>,
<ulink url="samba.7.html">samba(7)</ulink>, and
the Internet RFC1321 for details on the MD4 algorithm.
</para>
</refsect1>
<refsect1>
<title>AUTHOR</title>
<para>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.</para>
<para>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
<ulink url="ftp://ftp.icce.rug.nl/pub/unix/">
ftp://ftp.icce.rug.nl/pub/unix/</ulink>) and updated for the Samba 2.0
release by Jeremy Allison. The conversion to DocBook for
Samba 2.2 was done by Gerald Carter</para>
</refsect1>
</refentry>
|
