Apache Module mod_auth_digest
Summary
This module implements HTTP Digest Authentication. However, it
has not been extensively tested and is therefore marked
experimental.
Directives
Topics
See also
Using MD5 Digest authentication is very simple. Simply set
up authentication normally, using AuthType Digest and
AuthDigestFile instead
of the normal AuthType Basic and AuthUserFile; also, replace any AuthGroupFile with AuthDigestGroupFile. Then add a
AuthDigestDomain directive
containing at least the root URI(s) for this protection space.
Appropriate user (text) files can be created using the
htdigest tool.
Example:
<Location /private/>
AuthType Digest
AuthName "private area"
AuthDigestDomain /private/ http://mirror.my.dom/private2/
AuthDigestFile /web/auth/.digest_pw
Require valid-user
</Location>
Note
Digest authentication provides a more secure password system
than Basic authentication, but only works with supporting
browsers. As of November 2002, the major browsers that support digest
authentication are Opera, MS Internet
Explorer (fails when used with a query string), Amaya, Mozilla and Netscape since version 7. Since digest authentication is not
as widely implemented as basic authentication, you should use it only
in controlled environments.
The AuthDigestAlgorithm directive
selects the algorithm used to calculate the challenge and response
hashes.
MD5-sess is not correctly implemented yet.
The AuthDigestDomain directive allows
you to specify one or more URIs which are in the same protection
space (i.e. use the same realm and username/password info).
The specified URIs are prefixes, i.e. the client will assume
that all URIs "below" these are also protected by the same
username/password. The URIs may be either absolute URIs (i.e.
inluding a scheme, host, port, etc) or relative URIs.
This directive should always be specified and
contain at least the (set of) root URI(s) for this space.
Omitting to do so will cause the client to send the
Authorization header for every request sent to this
server. Apart from increasing the size of the request, it may
also have a detrimental effect on performance if AuthDigestNcCheck is on.
The URIs specified can also point to different servers, in
which case clients (which understand this) will then share
username/password info across multiple servers without
prompting the user each time.
The AuthDigestFile directive sets the
name of a textual file containing the list of users and encoded
passwords for digest authentication. File-path is the
absolute path to the user file.
The digest file uses a special format. Files in this format
can be created using the htdigest utility found in
the support/ subdirectory of the Apache distribution.
The AuthDigestGroupFile directive sets
the name of a textual file containing the list of groups and their
members (user names). File-path is the absolute path to
the group file.
Each line of the group file contains a groupname followed by
a colon, followed by the member usernames separated by spaces.
Example:
Note that searching large text files is very
inefficient.
Security:
Make sure that the AuthGroupFile is stored
outside the document tree of the web-server; do not put it in
the directory that it protects. Otherwise, clients may be able
to download the AuthGroupFile.
The AuthDigestNonceLifetime directive
controls how long the server nonce is valid. When the client
contacts the server using an expired nonce the server will send
back a 401 with stale=true. If seconds is
greater than 0 then it specifies the amount of time for which the
nonce is valid; this should probably never be set to less than 10
seconds. If seconds is less than 0 then the nonce never
expires.
The AuthDigestQop directive determines
the quality-of-protection to use. auth will only do
authentication (username/password); auth-int is
authentication plus integrity checking (an MD5 hash of the entity
is also computed and checked); none will cause the module
to use the old RFC-2069 digest algorithm (which does not include
integrity checking). Both auth and auth-int may
be specified, in which the case the browser will choose which of
these to use. none should only be used if the browser for
some reason does not like the challenge it receives otherwise.
auth-int is not implemented yet.
The AuthDigestShmemSize directive defines
the amount of shared memory, that will be allocated at the server
startup for keeping track of clients. Note that the shared memory
segment cannot be set less than the space that is neccessary for
tracking at least one client. This value is dependant on your
system. If you want to find out the exact value, you may simply
set AuthDigestShmemSize to the value of
0 and read the error message after trying to start the
server.
The size is normally expressed in Bytes, but you
may let the number follow a K or an M to
express your value as KBytes or MBytes. For example, the following
directives are all equivalent:
AuthDigestShmemSize 1048576
AuthDigestShmemSize 1024K
AuthDigestShmemSize 1M
