Apache Module mod_session_dbd
The session modules make use of HTTP cookies, and as such can fall victim to Cross Site Scripting attacks, or expose potentially private information to clients. Please ensure that the relevant risks have been taken into account before enabling the session functionality on your server.
provides support for the storage of user sessions within a SQL database using the mod_session
Sessions can either be anonymous, where the session is keyed by a unique UUID string stored on the browser in a cookie, or per user, where the session is keyed against the userid of the logged in user.
SQL based sessions are hidden from the browser, and so offer a measure of privacy without the need for encryption.
Different webservers within a server farm may choose to share a database, and so share sessions with one another.
For more details on the session interface, see the documentation for the
There are four queries required to keep a session maintained, to select an existing session, to update an existing session, to insert a new session, and to delete an expired or empty session. These queries are configured as per the example below.
DBDriver pgsql DBDParams "dbname=apachesession user=apache password=xxxxx host=localhost" DBDPrepareSQL "delete from session where key = %s" deletesession DBDPrepareSQL "update session set value = %s, expiry = %lld, key = %s where key = %s" updatesession DBDPrepareSQL "insert into session (value, expiry, key) values (%s, %lld, %s)" insertsession DBDPrepareSQL "select value from session where key = %s and (expiry = 0 or expiry > %lld)" selectsession DBDPrepareSQL "delete from session where expiry != 0 and expiry < %lld" cleansession
To create a simple anonymous session and store it in a postgres database table called apachesession, and save the session ID in a cookie called session, configure the session as follows:
For more examples on how the session can be configured to be read from and written to by a CGI application, see the
Per user sessions work within a correctly configured authenticated environment, be that using basic authentication, digest authentication or SSL client certificates. Due to the limitations of who came first, the chicken or the egg, per user sessions cannot be used to store authentication credentials from a module like
The administrator will need to set up an external process via cron to clean out expired sessions.
An optional list of cookie attributes can be specified, as per the example below. These attributes are inserted into the cookie as is, and are not interpreted by Apache. Ensure that your attributes are defined correctly as per the cookie specification.
Session On SessionDBDCookieName session path=/private;domain=example.com;httponly;secure;version=1;
In a reverse proxy situation where the Apache server acts as a server frontend for a backend origin server, revealing the contents of the session ID cookie to the backend could be a potential privacy violation. When set to on, the session ID cookie will be removed from the incoming HTTP headers.
If an attempt to update the session affects no rows, this query will be called to insert the session into the database.
If an attempt to update the session affects no rows, the insert query will be called to insert the session into the database. If the database supports InsertOrUpdate, override this query to perform the update in one query instead of two.
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Apache HTTP Server Version 2.4
Apache Module mod_session_dbd
Available Languages: en | fr
DBD Configuration
Before the mod_session_dbd module can be configured to maintain a session, the mod_dbd module must be configured to make the various database queries available to the server.
Anonymous Sessions
Anonymous sessions are keyed against a unique UUID, and stored on the browser within an HTTP cookie. This method is similar to that used by most application servers to store session information.
Per User Sessions
Per user sessions are keyed against the username of a successfully authenticated user. It offers the most privacy, as no external handle to the session exists outside of the authenticated realm.
Database Housekeeping
Over the course of time, the database can be expected to start accumulating expired sessions. At this point, the mod_session_dbd module is not yet able to handle session expiry automatically.
SessionDBDCookieName Directive
The SessionDBDCookieName directive specifies the name and optional attributes of an RFC2109 compliant cookie inside which the session ID will be stored. RFC2109 cookies are set using the Set-Cookie HTTP header.
SessionDBDCookieName2 Directive
The SessionDBDCookieName2 directive specifies the name and optional attributes of an RFC2965 compliant cookie inside which the session ID will be stored. RFC2965 cookies are set using the Set-Cookie2 HTTP header.
SessionDBDCookieRemove Directive
The SessionDBDCookieRemove flag controls whether the cookies containing the session ID will be removed from the headers during request processing.
SessionDBDDeleteLabel Directive
The SessionDBDDeleteLabel directive sets the default delete query label to be used to delete an expired or empty session. This label must have been previously defined using the DBDPrepareSQL directive.
SessionDBDInsertLabel Directive
The SessionDBDInsertLabel directive sets the default insert query label to be used to load in a session. This label must have been previously defined using the DBDPrepareSQL directive.
SessionDBDPerUser Directive
The SessionDBDPerUser flag enables a per user session keyed against the user's login name. If the user is not logged in, this directive will be ignored.
SessionDBDSelectLabel Directive
The SessionDBDSelectLabel directive sets the default select query label to be used to load in a session. This label must have been previously defined using the DBDPrepareSQL directive.
SessionDBDUpdateLabel Directive
The SessionDBDUpdateLabel directive sets the default update query label to be used to load in a session. This label must have been previously defined using the DBDPrepareSQL directive.