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7 <refentry id="smbpasswd.5">
10 <refentrytitle>smbpasswd</refentrytitle>
11 <manvolnum>5</manvolnum>
16 <refname>smbpasswd</refname>
17 <refpurpose>The Samba encrypted password file</refpurpose>
21 <para><filename>smbpasswd</filename></para>
25 <title>DESCRIPTION</title>
27 <para>This tool is part of the <citerefentry><refentrytitle>Samba</refentrytitle>
28 <manvolnum>7</manvolnum></citerefentry> suite.</para>
30 <para>smbpasswd is the Samba encrypted password file. It contains
31 the username, Unix user id and the SMB hashed passwords of the
32 user, as well as account flag information and the time the
33 password was last changed. This file format has been evolving with
34 Samba and has had several different formats in the past. </para>
38 <title>FILE FORMAT</title>
40 <para>The format of the smbpasswd file used by Samba 2.2
41 is very similar to the familiar Unix <filename>passwd(5)</filename>
42 file. It is an ASCII file containing one line for each user. Each field
43 ithin each line is separated from the next by a colon. Any entry
44 beginning with '#' is ignored. The smbpasswd file contains the
45 following information for each user: </para>
50 <listitem><para> This is the user name. It must be a name that
51 already exists in the standard UNIX passwd file. </para>
57 <listitem><para>This is the UNIX uid. It must match the uid
58 field for the same user entry in the standard UNIX passwd file.
59 If this does not match then Samba will refuse to recognize
60 this smbpasswd file entry as being valid for a user.
66 <term>Lanman Password Hash</term>
67 <listitem><para>This is the LANMAN hash of the user's password,
68 encoded as 32 hex digits. The LANMAN hash is created by DES
69 encrypting a well known string with the user's password as the
70 DES key. This is the same password used by Windows 95/98 machines.
71 Note that this password hash is regarded as weak as it is
72 vulnerable to dictionary attacks and if two users choose the
73 same password this entry will be identical (i.e. the password
74 is not "salted" as the UNIX password is). If the user has a
75 null password this field will contain the characters "NO PASSWORD"
76 as the start of the hex string. If the hex string is equal to
77 32 'X' characters then the user's account is marked as
78 <constant>disabled</constant> and the user will not be able to
79 log onto the Samba server. </para>
81 <para><emphasis>WARNING !!</emphasis> Note that, due to
82 the challenge-response nature of the SMB/CIFS authentication
83 protocol, anyone with a knowledge of this password hash will
84 be able to impersonate the user on the network. For this
85 reason these hashes are known as <emphasis>plain text
86 equivalents</emphasis> and must <emphasis>NOT</emphasis> be made
87 available to anyone but the root user. To protect these passwords
88 the smbpasswd file is placed in a directory with read and
89 traverse access only to the root user and the smbpasswd file
90 itself must be set to be read/write only by root, with no
91 other access. </para></listitem>
96 <term>NT Password Hash</term>
97 <listitem><para>This is the Windows NT hash of the user's
98 password, encoded as 32 hex digits. The Windows NT hash is
99 created by taking the user's password as represented in
100 16-bit, little-endian UNICODE and then applying the MD4
101 (internet rfc1321) hashing algorithm to it. </para>
103 <para>This password hash is considered more secure than
104 the LANMAN Password Hash as it preserves the case of the
105 password and uses a much higher quality hashing algorithm.
106 However, it is still the case that if two users choose the same
107 password this entry will be identical (i.e. the password is
108 not "salted" as the UNIX password is). </para>
110 <para><emphasis>WARNING !!</emphasis>. Note that, due to
111 the challenge-response nature of the SMB/CIFS authentication
112 protocol, anyone with a knowledge of this password hash will
113 be able to impersonate the user on the network. For this
114 reason these hashes are known as <emphasis>plain text
115 equivalents</emphasis> and must <emphasis>NOT</emphasis> be made
116 available to anyone but the root user. To protect these passwords
117 the smbpasswd file is placed in a directory with read and
118 traverse access only to the root user and the smbpasswd file
119 itself must be set to be read/write only by root, with no
120 other access. </para></listitem>
125 <term>Account Flags</term>
126 <listitem><para>This section contains flags that describe
127 the attributes of the users account. In the Samba 2.2 release
128 this field is bracketed by '[' and ']' characters and is always
129 13 characters in length (including the '[' and ']' characters).
130 The contents of this field may be any of the following characters:
134 <listitem><para><emphasis>U</emphasis> - This means
135 this is a "User" account, i.e. an ordinary user. Only User
136 and Workstation Trust accounts are currently supported
137 in the smbpasswd file. </para></listitem>
139 <listitem><para><emphasis>N</emphasis> - This means the
140 account has no password (the passwords in the fields LANMAN
141 Password Hash and NT Password Hash are ignored). Note that this
142 will only allow users to log on with no password if the <parameter>
143 null passwords</parameter> parameter is set in the <ulink
144 url="smb.conf.5.html#NULLPASSWORDS"><citerefentry><refentrytitle>smb.conf</refentrytitle>
145 <manvolnum>5</manvolnum></citerefentry></ulink> config file. </para></listitem>
147 <listitem><para><emphasis>D</emphasis> - This means the account
148 is disabled and no SMB/CIFS logins will be allowed for this user. </para></listitem>
150 <listitem><para><emphasis>W</emphasis> - This means this account
151 is a "Workstation Trust" account. This kind of account is used
152 in the Samba PDC code stream to allow Windows NT Workstations
153 and Servers to join a Domain hosted by a Samba PDC. </para>
157 <para>Other flags may be added as the code is extended in future.
158 The rest of this field space is filled in with spaces. </para>
164 <term>Last Change Time</term>
165 <listitem><para>This field consists of the time the account was
166 last modified. It consists of the characters 'LCT-' (standing for
167 "Last Change Time") followed by a numeric encoding of the UNIX time
168 in seconds since the epoch (1970) that the last change was made.
173 <para>All other colon separated fields are ignored at this time.</para>
177 <title>VERSION</title>
179 <para>This man page is correct for version 3.0 of
180 the Samba suite.</para>
184 <title>SEE ALSO</title>
185 <para><citerefentry><refentrytitle>smbpasswd</refentrytitle>
186 <manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>Samba</refentrytitle>
187 <manvolnum>7</manvolnum></citerefentry>, and
188 the Internet RFC1321 for details on the MD4 algorithm.
193 <title>AUTHOR</title>
195 <para>The original Samba software and related utilities
196 were created by Andrew Tridgell. Samba is now developed
197 by the Samba Team as an Open Source project similar
198 to the way the Linux kernel is developed.</para>
200 <para>The original Samba man pages were written by Karl Auer.
201 The man page sources were converted to YODL format (another
202 excellent piece of Open Source software, available at <ulink url="ftp://ftp.icce.rug.nl/pub/unix/">
203 ftp://ftp.icce.rug.nl/pub/unix/</ulink>) and updated for the Samba 2.0
204 release by Jeremy Allison. The conversion to DocBook for
205 Samba 2.2 was done by Gerald Carter. The conversion to DocBook XML 4.2
206 for Samba 3.0 was done by Alexander Bokovoy.</para>