mod_auth_digest - Apache HTTP Server Version 2.4









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Apache HTTP Server Version 2.4



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Apache Module mod_auth_digest

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Description:User authentication using MD5
    Digest Authentication
Status:Extension
Module Identifier:auth_digest_module
Source File:mod_auth_digest.c
Summary

    This module implements HTTP Digest Authentication
    (RFC2617), and
    provides an alternative to mod_auth_basic where the
    password is not transmitted as cleartext. However, this does
    not lead to a significant security advantage over
    basic authentication. On the other hand, the password storage on the
    server is much less secure with digest authentication than with
    basic authentication. Therefore, using basic auth and encrypting the
    whole connection using mod_ssl is a much better
    alternative.

Topics

 Using Digest Authentication
Directives

 AuthDigestAlgorithm
 AuthDigestDomain
 AuthDigestNonceLifetime
 AuthDigestProvider
 AuthDigestQop
 AuthDigestShmemSize

Bugfix checklisthttpd changelogKnown issuesReport a bugSee also

AuthName
AuthType
Require
Authentication howto
Comments


Using Digest Authentication

    To use MD5 Digest authentication, configure the location to be
    protected as shown in the below example:

    Example:<Location "/private/">
    AuthType Digest
    AuthName "private area"
    AuthDigestDomain "/private/" "http://mirror.my.dom/private2/"
    
    AuthDigestProvider file
    AuthUserFile "/web/auth/.digest_pw"
    Require valid-user
</Location>


    AuthDigestDomain
    should list the locations that will be protected by this
    configuration.

    The password file referenced in the AuthUserFile directive may be
    created and managed using the htdigest tool.


    Note
    Digest authentication was intended to be more secure than basic
    authentication, but no longer fulfills that design goal. A
    man-in-the-middle attacker can trivially force the browser to downgrade
    to basic authentication. And even a passive eavesdropper can brute-force
    the password using today's graphics hardware, because the hashing
    algorithm used by digest authentication is too fast. Another problem is
    that the storage of the passwords on the server is insecure. The contents
    of a stolen htdigest file can be used directly for digest authentication.
    Therefore using mod_ssl to encrypt the whole connection is
    strongly recommended.
    mod_auth_digest only works properly on platforms
      where APR supports shared memory.
    


AuthDigestAlgorithm Directive

Description:Selects the algorithm used to calculate the challenge and
response hashes in digest authentication
Syntax:AuthDigestAlgorithm MD5|MD5-sess
Default:AuthDigestAlgorithm MD5
Context:directory, .htaccess
Override:AuthConfig
Status:Extension
Module:mod_auth_digest

    The AuthDigestAlgorithm directive
    selects the algorithm used to calculate the challenge and response
    hashes.

    
      MD5-sess is not correctly implemented yet.
    
    



AuthDigestDomain Directive

Description:URIs that are in the same protection space for digest
authentication
Syntax:AuthDigestDomain URI [URI] ...
Context:directory, .htaccess
Override:AuthConfig
Status:Extension
Module:mod_auth_digest

    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; 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.
    including 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.

    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. 



AuthDigestNonceLifetime Directive

Description:How long the server nonce is valid
Syntax:AuthDigestNonceLifetime seconds
Default:AuthDigestNonceLifetime 300
Context:directory, .htaccess
Override:AuthConfig
Status:Extension
Module:mod_auth_digest

    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. 
    



AuthDigestProvider Directive

Description:Sets the authentication provider(s) for this location
Syntax:AuthDigestProvider provider-name
[provider-name] ...
Default:AuthDigestProvider file
Context:directory, .htaccess
Override:AuthConfig
Status:Extension
Module:mod_auth_digest

    The AuthDigestProvider directive sets
    which provider is used to authenticate the users for this location.
    The default file provider is implemented
    by the mod_authn_file module.  Make sure
    that the chosen provider module is present in the server.

    See mod_authn_dbm, mod_authn_file,
    mod_authn_dbd and mod_authn_socache
    for providers.



AuthDigestQop Directive

Description:Determines the quality-of-protection to use in digest
authentication
Syntax:AuthDigestQop none|auth|auth-int [auth|auth-int]
Default:AuthDigestQop auth
Context:directory, .htaccess
Override:AuthConfig
Status:Extension
Module:mod_auth_digest

    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.
    



AuthDigestShmemSize Directive

Description:The amount of shared memory to allocate for keeping track
of clients
Syntax:AuthDigestShmemSize size
Default:AuthDigestShmemSize 1000
Context:server config
Status:Extension
Module:mod_auth_digest

    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 necessary for
    tracking at least one client. This value is dependent 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 follow the number with 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





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