samba-mirror/docs-xml/manpages/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">&doc.version;</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 
	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: </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 part of version &doc.version; 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>
</refsect1>

</refentry>