source: branches/samba-3.3.x/docs-xml/manpages-3/smbpasswd.5.xml

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<!DOCTYPE refentry PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
<refentry id="smbpasswd.5">

<refmeta>
        <refentrytitle>smbpasswd</refentrytitle>
        <manvolnum>5</manvolnum>
        <refmiscinfo class="source">Samba</refmiscinfo>
        <refmiscinfo class="manual">File Formats and Conventions</refmiscinfo>
        <refmiscinfo class="version">3.3</refmiscinfo>
</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 <citerefentry><refentrytitle>samba</refentrytitle>
        <manvolnum>7</manvolnum></citerefentry> 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.  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:
                </para>
                
                <itemizedlist>
                        <listitem><para><emphasis>U</emphasis> - This means 
                        this is a "User" account, i.e. an ordinary user.</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 
                        <citerefentry><refentrytitle>smb.conf</refentrytitle>
                        <manvolnum>5</manvolnum></citerefentry> 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>X</emphasis> - This means the password 
                        does not expire. </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. For further
                information regarding the flags that are supported please refer to the
                man page for the <command>pdbedit</command> command.</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 of 
        the Samba suite.</para>
</refsect1>

<refsect1>
        <title>SEE ALSO</title>
        <para><citerefentry><refentrytitle>smbpasswd</refentrytitle>
        <manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>Samba</refentrytitle>
        <manvolnum>7</manvolnum></citerefentry>, 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 noescape="1" 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. The conversion to DocBook XML 4.2
        for Samba 3.0 was done by Alexander Bokovoy.</para>
</refsect1>

</refentry>