Apache HTTP Server Version 2.5
Description: | User authentication using an SQL database |
---|---|
Status: | Extension |
Module Identifier: | authn_dbd_module |
Source File: | mod_authn_dbd.c |
This module provides authentication front-ends such as
mod_auth_digest
and mod_auth_basic
to authenticate users by looking up users in SQL tables.
Similar functionality is provided by, for example,
mod_authn_file
.
This module relies on mod_dbd
to specify
the backend database driver and connection parameters, and
manage the database connections.
When using mod_auth_basic
or
mod_auth_digest
, this module is invoked via the
AuthBasicProvider
or
AuthDigestProvider
with the dbd
value.
Some users of DBD authentication in HTTPD 2.2/2.4 have reported that it
imposes a problematic load on the database. This is most likely where
an HTML page contains hundreds of objects (e.g. images, scripts, etc)
each of which requires authentication. Users affected (or concerned)
by this kind of problem should use mod_authn_socache
to cache credentials and take most of the load off the database.
This simple example shows use of this module in the context of the Authentication and DBD frameworks.
# mod_dbd configuration # UPDATED to include authentication cacheing DBDriver pgsql DBDParams "dbname=apacheauth user=apache password=xxxxxx" DBDMin 4 DBDKeep 8 DBDMax 20 DBDExptime 300 <Directory "/usr/www/myhost/private"> # mod_authn_core and mod_auth_basic configuration # for mod_authn_dbd AuthType Basic AuthName "My Server" # To cache credentials, put socache ahead of dbd here AuthBasicProvider socache dbd # Also required for caching: tell the cache to cache dbd lookups! AuthnCacheProvideFor dbd AuthnCacheContext my-server # mod_authz_core configuration Require valid-user # mod_authn_dbd SQL query to authenticate a user AuthDBDUserPWQuery "SELECT password FROM authn WHERE user = %s" </Directory>
If httpd was built against APR version 1.3.0 or higher, then whenever a query is made to the database server, all column values in the first row returned by the query are placed in the environment, using environment variables with the prefix "AUTHENTICATE_".
If a database query for example returned the username, full name and telephone number of a user, a CGI program will have access to this information without the need to make a second independent database query to gather this additional information.
This has the potential to dramatically simplify the coding and configuration required in some web applications.
Whether you need to care about SQL security depends on what DBD driver and backend you use. With most drivers you don't have to do anything : the statement is prepared by the database at startup, and user input is used only as data. But you may need to untaint your input. At the time of writing, the only driver that requires you to take care is FreeTDS.
Please read mod_dbd
documentation for more information
about security on this scope.
Description: | SQL query to look up a password for a user |
---|---|
Syntax: | AuthDBDUserPWQuery query |
Context: | directory |
Status: | Extension |
Module: | mod_authn_dbd |
The AuthDBDUserPWQuery
specifies an
SQL query to look up a password for a specified user. The user's ID
will be passed as a single string parameter when the SQL query is
executed. It may be referenced within the query statement using
a %s
format specifier.
AuthDBDUserPWQuery "SELECT password FROM authn WHERE user = %s"
The first column value of the first row returned by the query
statement should be a string containing the encrypted password.
Subsequent rows will be ignored. If no rows are returned, the user
will not be authenticated through mod_authn_dbd
.
If httpd was built against APR version 1.3.0
or higher, any additional column values in the first row returned by
the query statement will be stored as environment variables with
names of the form AUTHENTICATE_COLUMN
.
The encrypted password format depends on which authentication
frontend (e.g. mod_auth_basic
or
mod_auth_digest
) is being used. See Password Formats for
more information.
Description: | SQL query to look up a password hash for a user and realm. |
---|---|
Syntax: | AuthDBDUserRealmQuery query |
Context: | directory |
Status: | Extension |
Module: | mod_authn_dbd |
The AuthDBDUserRealmQuery
specifies an
SQL query to look up a password for a specified user and realm in a
digest authentication process.
The user's ID and the realm, in that order, will be passed as string
parameters when the SQL query is executed. They may be referenced
within the query statement using %s
format specifiers.
AuthDBDUserRealmQuery "SELECT password FROM authn WHERE user = %s AND realm = %s"
The first column value of the first row returned by the query
statement should be a string containing the encrypted password.
Subsequent rows will be ignored. If no rows are returned, the user
will not be authenticated through mod_authn_dbd
.
If httpd was built against APR version 1.3.0
or higher, any additional column values in the first row returned by
the query statement will be stored as environment variables with
names of the form AUTHENTICATE_COLUMN
.
The encrypted password format depends on which authentication
frontend (e.g. mod_auth_basic
or
mod_auth_digest
) is being used. See Password Formats for
more information.