2 <!DOCTYPE modulesynopsis SYSTEM "../style/modulesynopsis.dtd">
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4 <!-- $LastChangedRevision$ -->
7 Copyright 2002-2006 The Apache Software Foundation or its licensors, as
10 Licensed under the Apache License, Version 2.0 (the "License");
11 you may not use this file except in compliance with the License.
12 You may obtain a copy of the License at
14 http://www.apache.org/licenses/LICENSE-2.0
16 Unless required by applicable law or agreed to in writing, software
17 distributed under the License is distributed on an "AS IS" BASIS,
18 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
19 See the License for the specific language governing permissions and
20 limitations under the License.
23 <modulesynopsis metafile="mod_auth_digest.xml.meta">
25 <name>mod_auth_digest</name>
26 <description>User authentication using MD5
27 Digest Authentication.</description>
28 <status>Experimental</status>
29 <sourcefile>mod_auth_digest.c</sourcefile>
30 <identifier>auth_digest_module</identifier>
33 <p>This module implements HTTP Digest Authentication. However, it
34 has not been extensively tested and is therefore marked
38 <seealso><directive module="core">AuthName</directive></seealso>
39 <seealso><directive module="core">AuthType</directive></seealso>
40 <seealso><directive module="core">Require</directive></seealso>
41 <seealso><a href="../howto/auth.html">Authentication howto</a></seealso>
43 <section id="using"><title>Using Digest Authentication</title>
45 <p>Using MD5 Digest authentication is very simple. Simply set
46 up authentication normally, using <code>AuthType Digest</code> and
47 <directive module="mod_auth_digest">AuthDigestProvider</directive>
48 instead of the normal <code>AuthType Basic</code> and
49 <directive module="mod_auth_basic">AuthBasicProvider</directive>.
50 Then add a <directive module="mod_auth_digest"
51 >AuthDigestDomain</directive> directive containing at least the root
52 URI(s) for this protection space.</p>
54 <p>Appropriate user (text) files can be created using the
55 <program>htdigest</program> tool.</p>
57 <example><title>Example:</title>
58 <Location /private/><br />
61 AuthName "private area"<br />
62 AuthDigestDomain /private/ http://mirror.my.dom/private2/<br />
64 AuthDigestProvider file<br />
65 AuthUserFile /web/auth/.digest_pw<br />
66 Require valid-user<br />
71 <note><title>Note</title>
72 <p>Digest authentication is more secure than Basic authentication,
73 but only works with supporting browsers. As of September 2004, major
74 browsers that support digest authentication include <a
75 href="http://www.w3.org/Amaya/">Amaya</a>, <a
76 href="http://konqueror.kde.org/">Konqueror</a>, <a
77 href="http://www.microsoft.com/windows/ie/">MS Internet Explorer</a>
78 for Mac OS X and Windows (although the Windows version fails when
79 used with a query string -- see "<a href="#msie" >Working with MS
80 Internet Explorer</a>" below for a workaround), <a
81 href="http://www.mozilla.org">Mozilla</a>, <a
82 href="http://channels.netscape.com/ns/browsers/download.jsp">
83 Netscape</a> 7, <a href="http://www.opera.com/">Opera</a>, and <a
84 href="http://www.apple.com/safari/">Safari</a>. <a
85 href="http://lynx.isc.org/">lynx</a> does <strong>not</strong>
86 support digest authentication. Since digest authentication is not as
87 widely implemented as basic authentication, you should use it only
88 in environments where all users will have supporting browsers.</p>
92 <section id="msie"><title>Working with MS Internet Explorer</title>
93 <p>The Digest authentication implementation in current Internet
94 Explorer for Windows implementations has known issues, namely that
95 <code>GET</code> requests with a query string are not RFC compliant.
96 There are a few ways to work around this issue.</p>
99 The first way is to use <code>POST</code> requests instead of
100 <code>GET</code> requests to pass data to your program. This method
101 is the simplest approach if your application can work with this
105 <p>Since version 2.0.51 Apache also provides a workaround in the
106 <code>AuthDigestEnableQueryStringHack</code> environment variable.
107 If <code>AuthDigestEnableQueryStringHack</code> is set for the
108 request, Apache will take steps to work around the MSIE bug and
109 remove the request URI from the digest comparison. Using this
110 method would look similar to the following.</p>
112 <example><title>Using Digest Authentication with MSIE:</title>
113 BrowserMatch "MSIE" AuthDigestEnableQueryStringHack=On
116 <p>See the <directive module="mod_setenvif">BrowserMatch</directive>
117 directive for more details on conditionally setting environment
123 <name>AuthDigestProvider</name>
124 <description>Sets the authentication provider(s) for this location</description>
125 <syntax>AuthDigestProvider <var>provider-name</var>
126 [<var>provider-name</var>] ...</syntax>
127 <default>AuthDigestProvider file</default>
128 <contextlist><context>directory</context><context>.htaccess</context>
130 <override>AuthConfig</override>
133 <p>The <directive>AuthDigestProvider</directive> directive sets
134 which provider is used to authenticate the users for this location.
135 The default <code>file</code> provider is implemented
136 by the <module>mod_authn_file</module> module. Make sure
137 that the chosen provider module is present in the server.</p>
139 <p>See <module>mod_authn_dbm</module>, <module>mod_authn_file</module>,
140 and <module>mod_authn_dbd</module> for providers.</p>
145 <name>AuthDigestQop</name>
146 <description>Determines the quality-of-protection to use in digest
147 authentication</description>
148 <syntax>AuthDigestQop none|auth|auth-int [auth|auth-int]</syntax>
149 <default>AuthDigestQop auth</default>
150 <contextlist><context>directory</context><context>.htaccess</context>
152 <override>AuthConfig</override>
155 <p>The <directive>AuthDigestQop</directive> directive determines
156 the <dfn>quality-of-protection</dfn> to use. <code>auth</code> will
157 only do authentication (username/password); <code>auth-int</code> is
158 authentication plus integrity checking (an MD5 hash of the entity
159 is also computed and checked); <code>none</code> will cause the module
160 to use the old RFC-2069 digest algorithm (which does not include
161 integrity checking). Both <code>auth</code> and <code>auth-int</code> may
162 be specified, in which the case the browser will choose which of
163 these to use. <code>none</code> should only be used if the browser for
164 some reason does not like the challenge it receives otherwise.</p>
167 <code>auth-int</code> is not implemented yet.
173 <name>AuthDigestNonceLifetime</name>
174 <description>How long the server nonce is valid</description>
175 <syntax>AuthDigestNonceLifetime <var>seconds</var></syntax>
176 <default>AuthDigestNonceLifetime 300</default>
177 <contextlist><context>directory</context><context>.htaccess</context>
179 <override>AuthConfig</override>
182 <p>The <directive>AuthDigestNonceLifetime</directive> directive
183 controls how long the server nonce is valid. When the client
184 contacts the server using an expired nonce the server will send
185 back a 401 with <code>stale=true</code>. If <var>seconds</var> is
186 greater than 0 then it specifies the amount of time for which the
187 nonce is valid; this should probably never be set to less than 10
188 seconds. If <var>seconds</var> is less than 0 then the nonce never
189 expires. <!-- Not implemented yet: If <var>seconds</var> is 0 then
190 the nonce may be used exactly once by the client. Note that while
191 one-time-nonces provide higher security against replay attacks,
192 they also have significant performance implications, as the
193 browser cannot pipeline or multiple connections for the
194 requests. Because browsers cannot easily detect that
195 one-time-nonces are being used, this may lead to browsers trying
196 to pipeline requests and receiving 401 responses for all but the
197 first request, requiring the browser to resend the requests. Note
198 also that the protection against reply attacks only makes sense
199 for dynamically generated content and things like POST requests;
200 for static content the attacker may already have the complete
201 response, so one-time-nonces do not make sense here. -->
207 <name>AuthDigestNonceFormat</name>
208 <description>Determines how the nonce is generated</description>
209 <syntax>AuthDigestNonceFormat <var>format</var></syntax>
210 <contextlist><context>directory</context><context>.htaccess</context>
212 <override>AuthConfig</override>
215 <note>Not implemented yet.</note>
216 <!-- The AuthDigestNonceFormat directive determines how the nonce is
222 <name>AuthDigestNcCheck</name>
223 <description>Enables or disables checking of the nonce-count sent by the
225 <syntax>AuthDigestNcCheck On|Off</syntax>
226 <default>AuthDigestNcCheck Off</default>
227 <contextlist><context>server config</context></contextlist>
234 <p>The AuthDigestNcCheck directive enables or disables the checking of the
235 nonce-count sent by the server.</p>
237 <p>While recommended from a security standpoint, turning this directive
238 On has one important performance implication. To check the nonce-count
239 *all* requests (which have an Authorization header, irrespective of
240 whether they require digest authentication) must be serialized through
241 a critical section. If the server is handling a large number of
242 requests which contain the Authorization header then this may noticeably
243 impact performance.</p>
249 <name>AuthDigestAlgorithm</name>
250 <description>Selects the algorithm used to calculate the challenge and
251 response hashes in digest authentication</description>
252 <syntax>AuthDigestAlgorithm MD5|MD5-sess</syntax>
253 <default>AuthDigestAlgorithm MD5</default>
254 <contextlist><context>directory</context><context>.htaccess</context>
256 <override>AuthConfig</override>
259 <p>The <directive>AuthDigestAlgorithm</directive> directive
260 selects the algorithm used to calculate the challenge and response
264 <code>MD5-sess</code> is not correctly implemented yet.
267 <p>To use <code>MD5-sess</code> you must first code up the
268 <code>get_userpw_hash()</code> function in
269 <code>mod_auth_digest.c</code>.</p>
275 <name>AuthDigestDomain</name>
276 <description>URIs that are in the same protection space for digest
277 authentication</description>
278 <syntax>AuthDigestDomain <var>URI</var> [<var>URI</var>] ...</syntax>
279 <contextlist><context>directory</context><context>.htaccess</context>
281 <override>AuthConfig</override>
284 <p>The <directive>AuthDigestDomain</directive> directive allows
285 you to specify one or more URIs which are in the same protection
286 space (<em>i.e.</em> use the same realm and username/password info).
287 The specified URIs are prefixes; the client will assume
288 that all URIs "below" these are also protected by the same
289 username/password. The URIs may be either absolute URIs (<em>i.e.</em>
290 including a scheme, host, port, etc.) or relative URIs.</p>
292 <p>This directive <em>should</em> always be specified and
293 contain at least the (set of) root URI(s) for this space.
294 Omitting to do so will cause the client to send the
295 Authorization header for <em>every request</em> sent to this
296 server. Apart from increasing the size of the request, it may
297 also have a detrimental effect on performance if <directive
298 module="mod_auth_digest">AuthDigestNcCheck</directive> is on.</p>
300 <p>The URIs specified can also point to different servers, in
301 which case clients (which understand this) will then share
302 username/password info across multiple servers without
303 prompting the user each time. </p>
308 <name>AuthDigestShmemSize</name>
309 <description>The amount of shared memory to allocate for keeping track
310 of clients</description>
311 <syntax>AuthDigestShmemSize <var>size</var></syntax>
312 <default>AuthDigestShmemSize 1000</default>
313 <contextlist><context>server config</context></contextlist>
316 <p>The <directive>AuthDigestShmemSize</directive> directive defines
317 the amount of shared memory, that will be allocated at the server
318 startup for keeping track of clients. Note that the shared memory
319 segment cannot be set less than the space that is necessary for
320 tracking at least <em>one</em> client. This value is dependant on your
321 system. If you want to find out the exact value, you may simply
322 set <directive>AuthDigestShmemSize</directive> to the value of
323 <code>0</code> and read the error message after trying to start the
326 <p>The <var>size</var> is normally expressed in Bytes, but you
327 may let the number follow a <code>K</code> or an <code>M</code> to
328 express your value as KBytes or MBytes. For example, the following
329 directives are all equivalent:</p>
332 AuthDigestShmemSize 1048576<br />
333 AuthDigestShmemSize 1024K<br />
334 AuthDigestShmemSize 1M