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Apache HTTP Server Version 1.3
Module mod_auth_dbm
This module provides for user authentication using DBM files.
Status:
Extension
Source
File: mod_auth_dbm.c
Module
Identifier: dbm_auth_module
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 and the
Berkely DB password files provided by
mod_auth_db.
Directives
See also: Satisfy and
Require.
Syntax:
AuthDBMGroupFile file-path
Context:
directory, .htaccess
Override:
AuthConfig
Status:
Extension
Module:
mod_auth_dbm
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.
See also AuthName,
AuthType and
AuthDBMUserFile.
Syntax:
AuthDBMUserFile file-path
Context:
directory, .htaccess
Override:
AuthConfig
Status:
Extension
Module:
mod_auth_dbm
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.
See also AuthName,
AuthType and
AuthDBMGroupFile.
Syntax:
AuthDBMAuthoritative on|off
Default:
AuthDBMAuthoritative on
Context:
directory, .htaccess
Override:
AuthConfig
Status:
Extension
Module:
mod_auth_dbm
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.c. 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 behavior.
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.
See also AuthName,
AuthType and
AuthDBMGroupFile.
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