Apache HTTP Server Version 2.2
Apache Module mod_authz_dbm
| Description: | Group authorization using DBM files |
|---|---|
| Status: | Extension |
| Module Identifier: | authz_dbm_module |
| Source File: | mod_authz_dbm.c |
| Compatibility: | Available in Apache 2.1 and later |
Summary
This module provides authorization capabilities so that
authenticated users can be allowed or denied access to portions
of the web site by group membership. Similar functionality is
provided by mod_authz_groupfile.
AuthDBMGroupFile Directive
| Description: | Sets the name of the database file containing the list of user groups for authorization |
|---|---|
| Syntax: | AuthDBMGroupFile file-path |
| Context: | directory, .htaccess |
| Override: | AuthConfig |
| Status: | Extension |
| Module: | mod_authz_dbm |
The AuthDBMGroupFile directive sets the
name of a DBM file containing the list of user groups for user
authorization. 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
Encrypted Password : List of Groups [ : (ignored) ]
The password section contains the encrypted 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 authorization module. This is what www.telescope.org uses for its combined password and group database.
AuthzDBMAuthoritative Directive
| Description: | Sets whether authorization will be passed on to lower level modules |
|---|---|
| Syntax: | AuthzDBMAuthoritative On|Off |
| Default: | AuthzDBMAuthoritative On |
| Context: | directory, .htaccess |
| Override: | AuthConfig |
| Status: | Extension |
| Module: | mod_authz_dbm |
Setting the AuthzDBMAuthoritative
directive explicitly to Off allows group authorization
to be passed on to lower level modules (as defined in the
modules.c file) if there is no group found
for the supplied userID. If there are any groups
specified, the usual checks will be applied and a failure will
give an Authentication 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
auth providers; such as mod_authn_dbm or
mod_authn_file. 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 group will result in an Authentication 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.
AuthzDBMType Directive
| Description: | Sets the type of database file that is used to store list of user groups |
|---|---|
| Syntax: | AuthzDBMType default|SDBM|GDBM|NDBM|DB |
| Default: | AuthzDBMType default |
| Context: | directory, .htaccess |
| Override: | AuthConfig |
| Status: | Extension |
| Module: | mod_authz_dbm |
Sets the type of database file that is used to store the list of user groups. 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 group files is configured to use the same type of database.