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Apache HTTP Server Version 2.0
Apache Module mod_auth_dbm
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Summary
This module provides for HTTP Basic Authentication, where
the usernames and passwords are stored in DBM type database
files. It is an alternative to the plain text password files
provided by mod_auth.
Directives
See also
AuthDBMAuthoritative Directive
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This information has not been updated to take into account the new module ordering techniques in Apache 2.0
Setting the AuthDBMAuthoritative
directive explicitly to 'off' allows for both
authentication and authorization to be passed on to lower level
modules (as defined in the Configuration and
modules.c file if there is no userID
or rule matching the supplied userID. If there is
a userID and/or rule specified; the usual password and access
checks will be applied and a failure will give an Authorization
Required reply.
So if a userID appears in the database of more than one module;
or if a valid Require
directive applies to more than one module; then the first module
will verify the credentials; and no access is passed on;
regardless of the AuthAuthoritative setting.
A common use for this is in conjunction with one of the
basic auth modules; such as mod_auth. Whereas this
DBM module supplies the bulk of the user credential checking; a
few (administrator) related accesses fall through to a lower
level with a well protected .htpasswd file.
By default, control is not passed on and an unknown userID or rule will result in an Authorization Required reply. Not setting it thus keeps the system secure and forces an NCSA compliant behaviour.
Security: Do consider the implications of allowing a user to allow fall-through in his .htaccess file; and verify that this is really what you want; Generally it is easier to just secure a single .htpasswd file, than it is to secure a database which might have more access interfaces.
AuthDBMGroupFile Directive
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The AuthDBMGroupFile directive sets the
name of a DBM file containing the list of user groups for user
authentication. File-path is the absolute path to the
group file.
The group file is keyed on the username. The value for a user is a comma-separated list of the groups to which the users belongs. There must be no whitespace within the value, and it must never contain any colons.
Security: make sure that the
AuthDBMGroupFile is stored outside the
document tree of the web-server; do not put it in the
directory that it protects. Otherwise, clients will be able to
download the AuthDBMGroupFile unless
otherwise protected.
Combining Group and Password DBM files: In some cases it is easier to manage a single database which contains both the password and group details for each user. This simplifies any support programs that need to be written: they now only have to deal with writing to and locking a single DBM file. This can be accomplished by first setting the group and password files to point to the same DBM:
AuthDBMGroupFile /www/userbase
AuthDBMUserFile /www/userbase
The key for the single DBM is the username. The value consists of
Unix Crypt-ed Password : List of Groups [ : (ignored) ]
The password section contains the Unix crypt()
password as before. This is followed by a colon and the comma
separated list of groups. Other data may optionally be left in the
DBM file after another colon; it is ignored by the authentication
module. This is what www.telescope.org uses for its combined
password and group database.
AuthDBMType Directive
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Sets the type of database file that is used to store the passwords. The default database type is determined at compile time. The availability of other types of database files also depends on compile-time settings.
It is crucial that whatever program you use to create your password files is configured to use the same type of database.
AuthDBMUserFile Directive
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The AuthDBMUserFile directive sets the
name of a DBM file containing the list of users and passwords for
user authentication. File-path is the absolute path to
the user file.
The user file is keyed on the username. The value for a user is
the crypt() encrypted password, optionally followed
by a colon and arbitrary data. The colon and the data following it
will be ignored by the server.
Security: make sure that the
AuthDBMUserFile is stored outside the
document tree of the web-server; do not put it in the
directory that it protects. Otherwise, clients will be able to
download the AuthDBMUserFile.
Important compatibility note: The implementation of "dbmopen" in the apache modules reads the string length of the hashed values from the DBM data structures, rather than relying upon the string being NULL-appended. Some applications, such as the Netscape web server, rely upon the string being NULL-appended, so if you are having trouble using DBM files interchangeably between applications this may be a part of the problem.
A perl script called dbmmanage is included with Apache. This program can be used to create and update DBM format password files for use with this module.
