| 1 | <samba:parameter name="smb encrypt"
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| 2 | context="S"
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| 3 | type="enum"
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| 4 | enumlist="enum_smb_signing_vals"
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| 5 | xmlns:samba="http://www.samba.org/samba/DTD/samba-doc">
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| 6 | <description>
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| 7 | <para>
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| 8 | This parameter controls whether a remote client is allowed or required
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| 9 | to use SMB encryption. It has different effects depending on whether
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| 10 | the connection uses SMB1 or SMB2 and newer:
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| 11 | </para>
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| 12 |
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| 13 | <itemizedlist>
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| 14 | <listitem>
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| 15 | <para>
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| 16 | If the connection uses SMB1, then this option controls the use
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| 17 | of a Samba-specific extension to the SMB protocol introduced in
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| 18 | Samba 3.2 that makes use of the Unix extensions.
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| 19 | </para>
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| 20 | </listitem>
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| 21 |
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| 22 | <listitem>
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| 23 | <para>
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| 24 | If the connection uses SMB2 or newer, then this option controls
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| 25 | the use of the SMB-level encryption that is supported in SMB
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| 26 | version 3.0 and above and available in Windows 8 and newer.
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| 27 | </para>
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| 28 | </listitem>
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| 29 | </itemizedlist>
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| 30 |
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| 31 | <para>
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| 32 | This parameter can be set globally and on a per-share bases.
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| 33 | Possible values are
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| 34 | <emphasis>off</emphasis> (or <emphasis>disabled</emphasis>),
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| 35 | <emphasis>enabled</emphasis> (or <emphasis>auto</emphasis>, or
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| 36 | <emphasis>if_required</emphasis>),
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| 37 | <emphasis>desired</emphasis>,
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| 38 | and
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| 39 | <emphasis>required</emphasis>
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| 40 | (or <emphasis>mandatory</emphasis>).
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| 41 | A special value is <emphasis>default</emphasis> which is
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| 42 | the implicit default setting of <emphasis>enabled</emphasis>.
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| 43 | </para>
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| 44 |
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| 45 | <variablelist>
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| 46 | <varlistentry>
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| 47 | <term><emphasis>Effects for SMB1</emphasis></term>
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| 48 | <listitem>
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| 49 | <para>
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| 50 | The Samba-specific encryption of SMB1 connections is an
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| 51 | extension to the SMB protocol negotiated as part of the UNIX
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| 52 | extensions. SMB encryption uses the GSSAPI (SSPI on Windows)
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| 53 | ability to encrypt and sign every request/response in a SMB
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| 54 | protocol stream. When enabled it provides a secure method of
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| 55 | SMB/CIFS communication, similar to an ssh protected session, but
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| 56 | using SMB/CIFS authentication to negotiate encryption and
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| 57 | signing keys. Currently this is only supported smbclient of by
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| 58 | Samba 3.2 and newer, and hopefully soon Linux CIFSFS and MacOS/X
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| 59 | clients. Windows clients do not support this feature.
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| 60 | </para>
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| 61 |
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| 62 | <para>This may be set on a per-share
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| 63 | basis, but clients may chose to encrypt the entire session, not
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| 64 | just traffic to a specific share. If this is set to mandatory
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| 65 | then all traffic to a share <emphasis>must</emphasis>
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| 66 | be encrypted once the connection has been made to the share.
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| 67 | The server would return "access denied" to all non-encrypted
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| 68 | requests on such a share. Selecting encrypted traffic reduces
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| 69 | throughput as smaller packet sizes must be used (no huge UNIX
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| 70 | style read/writes allowed) as well as the overhead of encrypting
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| 71 | and signing all the data.
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| 72 | </para>
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| 73 |
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| 74 | <para>
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| 75 | If SMB encryption is selected, Windows style SMB signing (see
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| 76 | the <smbconfoption name="server signing"/> option) is no longer
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| 77 | necessary, as the GSSAPI flags use select both signing and
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| 78 | sealing of the data.
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| 79 | </para>
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| 80 |
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| 81 | <para>
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| 82 | When set to auto or default, SMB encryption is offered, but not
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| 83 | enforced. When set to mandatory, SMB encryption is required and
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| 84 | if set to disabled, SMB encryption can not be negotiated.
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| 85 | </para>
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| 86 | </listitem>
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| 87 | </varlistentry>
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| 88 |
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| 89 | <varlistentry>
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| 90 | <term><emphasis>Effects for SMB2</emphasis></term>
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| 91 | <listitem>
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| 92 | <para>
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| 93 | Native SMB transport encryption is available in SMB version 3.0
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| 94 | or newer. It is only offered by Samba if
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| 95 | <emphasis>server max protocol</emphasis> is set to
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| 96 | <emphasis>SMB3</emphasis> or newer.
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| 97 | Clients supporting this type of encryption include
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| 98 | Windows 8 and newer,
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| 99 | Windows server 2012 and newer,
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| 100 | and smbclient of Samba 4.1 and newer.
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| 101 | </para>
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| 102 |
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| 103 | <para>
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| 104 | The protocol implementation offers various options:
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| 105 | </para>
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| 106 |
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| 107 | <itemizedlist>
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| 108 | <listitem>
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| 109 | <para>
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| 110 | The capability to perform SMB encryption can be
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| 111 | negotiated during protocol negotiation.
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| 112 | </para>
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| 113 | </listitem>
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| 114 |
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| 115 | <listitem>
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| 116 | <para>
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| 117 | Data encryption can be enabled globally. In that case,
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| 118 | an encryption-capable connection will have all traffic
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| 119 | in all its sessions encrypted. In particular all share
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| 120 | connections will be encrypted.
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| 121 | </para>
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| 122 | </listitem>
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| 123 |
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| 124 | <listitem>
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| 125 | <para>
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| 126 | Data encryption can also be enabled per share if not
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| 127 | enabled globally. For an encryption-capable connection,
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| 128 | all connections to an encryption-enabled share will be
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| 129 | encrypted.
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| 130 | </para>
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| 131 | </listitem>
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| 132 |
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| 133 | <listitem>
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| 134 | <para>
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| 135 | Encryption can be enforced. This means that session
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| 136 | setups will be denied on non-encryption-capable
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| 137 | connections if data encryption has been enabled
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| 138 | globally. And tree connections will be denied for
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| 139 | non-encryption capable connections to shares with data
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| 140 | encryption enabled.
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| 141 | </para>
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| 142 | </listitem>
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| 143 | </itemizedlist>
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| 144 |
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| 145 | <para>
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| 146 | These features can be controlled with settings of
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| 147 | <emphasis>smb encrypt</emphasis> as follows:
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| 148 | </para>
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| 149 |
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| 150 | <itemizedlist>
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| 151 | <listitem>
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| 152 | <para>
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| 153 | Leaving it as default, explicitly setting
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| 154 | <emphasis>default</emphasis>, or setting it to
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| 155 | <emphasis>enabled</emphasis> globally will enable
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| 156 | negotiation of encryption but will not turn on
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| 157 | data encryption globally or per share.
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| 158 | </para>
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| 159 | </listitem>
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| 160 |
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| 161 | <listitem>
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| 162 | <para>
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| 163 | Setting it to <emphasis>desired</emphasis> globally
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| 164 | will enable negotiation and will turn on data encryption
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| 165 | on sessions and share connections for those clients
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| 166 | that support it.
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| 167 | </para>
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| 168 | </listitem>
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| 169 |
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| 170 | <listitem>
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| 171 | <para>
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| 172 | Setting it to <emphasis>required</emphasis> globally
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| 173 | will enable negotiation and turn on data encryption
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| 174 | on sessions and share connections. Clients that do
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| 175 | not support encryption will be denied access to the
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| 176 | server.
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| 177 | </para>
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| 178 | </listitem>
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| 179 |
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| 180 | <listitem>
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| 181 | <para>
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| 182 | Setting it to <emphasis>off</emphasis> globally will
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| 183 | completely disable the encryption feature.
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| 184 | </para>
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| 185 | </listitem>
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| 186 |
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| 187 | <listitem>
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| 188 | <para>
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| 189 | Setting it to <emphasis>desired</emphasis> on a share
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| 190 | will turn on data encryption for this share for clients
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| 191 | that support encryption if negotiation has been
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| 192 | enabled globally.
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| 193 | </para>
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| 194 | </listitem>
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| 195 |
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| 196 | <listitem>
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| 197 | <para>
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| 198 | Setting it to <emphasis>required</emphasis> on a share
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| 199 | will enforce data encryption for this share if
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| 200 | negotiation has been enabled globally. I.e. clients that
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| 201 | do not support encryption will be denied access to the
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| 202 | share.
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| 203 | </para>
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| 204 | <para>
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| 205 | Note that this allows per-share enforcing to be
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| 206 | controlled in Samba differently from Windows:
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| 207 | In Windows, <emphasis>RejectUnencryptedAccess</emphasis>
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| 208 | is a global setting, and if it is set, all shares with
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| 209 | data encryption turned on
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| 210 | are automatically enforcing encryption. In order to
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| 211 | achieve the same effect in Samba, one
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| 212 | has to globally set <emphasis>smb encrypt</emphasis> to
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| 213 | <emphasis>enabled</emphasis>, and then set all shares
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| 214 | that should be encrypted to
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| 215 | <emphasis>required</emphasis>.
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| 216 | Additionally, it is possible in Samba to have some
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| 217 | shares with encryption <emphasis>required</emphasis>
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| 218 | and some other shares with encryption only
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| 219 | <emphasis>desired</emphasis>, which is not possible in
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| 220 | Windows.
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| 221 | </para>
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| 222 | </listitem>
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| 223 |
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| 224 | <listitem>
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| 225 | <para>
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| 226 | Setting it to <emphasis>off</emphasis> or
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| 227 | <emphasis>enabled</emphasis> for a share has
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| 228 | no effect.
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| 229 | </para>
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| 230 | </listitem>
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| 231 | </itemizedlist>
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| 232 | </listitem>
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| 233 | </varlistentry>
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| 234 | </variablelist>
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| 235 | </description>
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| 236 |
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| 237 | <value type="default">default</value>
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| 238 | </samba:parameter>
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