Apache Module mod_authz_dbm

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.

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:

The key for the single DBM is the username. The value consists of

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 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.

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.