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6 <refentry id="smbpasswd.5">
9 <refentrytitle>smbpasswd</refentrytitle>
10 <manvolnum>5</manvolnum>
15 <refname>smbpasswd</refname>
16 <refpurpose>The Samba encrypted password file</refpurpose>
20 <para><filename>smbpasswd</filename></para>
24 <title>DESCRIPTION</title>
26 <para>This tool is part of the <citerefentry><refentrytitle>samba</refentrytitle>
27 <manvolnum>7</manvolnum></citerefentry> suite.</para>
29 <para>smbpasswd is the Samba encrypted password file. It contains
30 the username, Unix user id and the SMB hashed passwords of the
31 user, as well as account flag information and the time the
32 password was last changed. This file format has been evolving with
33 Samba and has had several different formats in the past. </para>
37 <title>FILE FORMAT</title>
39 <para>The format of the smbpasswd file used by Samba 2.2
40 is very similar to the familiar Unix <filename>passwd(5)</filename>
41 file. It is an ASCII file containing one line for each user. Each field
42 ithin each line is separated from the next by a colon. Any entry
43 beginning with '#' is ignored. The smbpasswd file contains the
44 following information for each user: </para>
49 <listitem><para> This is the user name. It must be a name that
50 already exists in the standard UNIX passwd file. </para>
56 <listitem><para>This is the UNIX uid. It must match the uid
57 field for the same user entry in the standard UNIX passwd file.
58 If this does not match then Samba will refuse to recognize
59 this smbpasswd file entry as being valid for a user.
65 <term>Lanman Password Hash</term>
66 <listitem><para>This is the LANMAN hash of the user's password,
67 encoded as 32 hex digits. The LANMAN hash is created by DES
68 encrypting a well known string with the user's password as the
69 DES key. This is the same password used by Windows 95/98 machines.
70 Note that this password hash is regarded as weak as it is
71 vulnerable to dictionary attacks and if two users choose the
72 same password this entry will be identical (i.e. the password
73 is not "salted" as the UNIX password is). If the user has a
74 null password this field will contain the characters "NO PASSWORD"
75 as the start of the hex string. If the hex string is equal to
76 32 'X' characters then the user's account is marked as
77 <constant>disabled</constant> and the user will not be able to
78 log onto the Samba server. </para>
80 <para><emphasis>WARNING !!</emphasis> Note that, due to
81 the challenge-response nature of the SMB/CIFS authentication
82 protocol, anyone with a knowledge of this password hash will
83 be able to impersonate the user on the network. For this
84 reason these hashes are known as <emphasis>plain text
85 equivalents</emphasis> and must <emphasis>NOT</emphasis> be made
86 available to anyone but the root user. To protect these passwords
87 the smbpasswd file is placed in a directory with read and
88 traverse access only to the root user and the smbpasswd file
89 itself must be set to be read/write only by root, with no
90 other access. </para></listitem>
95 <term>NT Password Hash</term>
96 <listitem><para>This is the Windows NT hash of the user's
97 password, encoded as 32 hex digits. The Windows NT hash is
98 created by taking the user's password as represented in
99 16-bit, little-endian UNICODE and then applying the MD4
100 (internet rfc1321) hashing algorithm to it. </para>
102 <para>This password hash is considered more secure than
103 the LANMAN Password Hash as it preserves the case of the
104 password and uses a much higher quality hashing algorithm.
105 However, it is still the case that if two users choose the same
106 password this entry will be identical (i.e. the password is
107 not "salted" as the UNIX password is). </para>
109 <para><emphasis>WARNING !!</emphasis>. Note that, due to
110 the challenge-response nature of the SMB/CIFS authentication
111 protocol, anyone with a knowledge of this password hash will
112 be able to impersonate the user on the network. For this
113 reason these hashes are known as <emphasis>plain text
114 equivalents</emphasis> and must <emphasis>NOT</emphasis> be made
115 available to anyone but the root user. To protect these passwords
116 the smbpasswd file is placed in a directory with read and
117 traverse access only to the root user and the smbpasswd file
118 itself must be set to be read/write only by root, with no
119 other access. </para></listitem>
124 <term>Account Flags</term>
125 <listitem><para>This section contains flags that describe
126 the attributes of the users account. In the Samba 2.2 release
127 this field is bracketed by '[' and ']' characters and is always
128 13 characters in length (including the '[' and ']' characters).
129 The contents of this field may be any of the following characters:
133 <listitem><para><emphasis>U</emphasis> - This means
134 this is a "User" account, i.e. an ordinary user. Only User
135 and Workstation Trust accounts are currently supported
136 in the smbpasswd file. </para></listitem>
138 <listitem><para><emphasis>N</emphasis> - This means the
139 account has no password (the passwords in the fields LANMAN
140 Password Hash and NT Password Hash are ignored). Note that this
141 will only allow users to log on with no password if the <parameter>
142 null passwords</parameter> parameter is set in the
143 <citerefentry><refentrytitle>smb.conf</refentrytitle>
144 <manvolnum>5</manvolnum></citerefentry> config file. </para></listitem>
146 <listitem><para><emphasis>D</emphasis> - This means the account
147 is disabled and no SMB/CIFS logins will be allowed for this user. </para></listitem>
149 <listitem><para><emphasis>W</emphasis> - This means this account
150 is a "Workstation Trust" account. This kind of account is used
151 in the Samba PDC code stream to allow Windows NT Workstations
152 and Servers to join a Domain hosted by a Samba PDC. </para>
156 <para>Other flags may be added as the code is extended in future.
157 The rest of this field space is filled in with spaces. </para>
163 <term>Last Change Time</term>
164 <listitem><para>This field consists of the time the account was
165 last modified. It consists of the characters 'LCT-' (standing for
166 "Last Change Time") followed by a numeric encoding of the UNIX time
167 in seconds since the epoch (1970) that the last change was made.
172 <para>All other colon separated fields are ignored at this time.</para>
176 <title>VERSION</title>
178 <para>This man page is correct for version 3.0 of
179 the Samba suite.</para>
183 <title>SEE ALSO</title>
184 <para><citerefentry><refentrytitle>smbpasswd</refentrytitle>
185 <manvolnum>8</manvolnum></citerefentry>, <citerefentry><refentrytitle>Samba</refentrytitle>
186 <manvolnum>7</manvolnum></citerefentry>, and
187 the Internet RFC1321 for details on the MD4 algorithm.
192 <title>AUTHOR</title>
194 <para>The original Samba software and related utilities
195 were created by Andrew Tridgell. Samba is now developed
196 by the Samba Team as an Open Source project similar
197 to the way the Linux kernel is developed.</para>
199 <para>The original Samba man pages were written by Karl Auer.
200 The man page sources were converted to YODL format (another
201 excellent piece of Open Source software, available at <ulink noescape="1" url="ftp://ftp.icce.rug.nl/pub/unix/">
202 ftp://ftp.icce.rug.nl/pub/unix/</ulink>) and updated for the Samba 2.0
203 release by Jeremy Allison. The conversion to DocBook for
204 Samba 2.2 was done by Gerald Carter. The conversion to DocBook XML 4.2
205 for Samba 3.0 was done by Alexander Bokovoy.</para>