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<modulesynopsis metafile="mod_session_dbd.xml.meta">

<name>mod_session_dbd</name>

<description>DBD/SQL based session support</description>

<status>Extension</status>

<sourcefile>mod_session_dbd.c</sourcefile>

<identifier>session_dbd_module</identifier>

<compatibility>Available in Apache 2.3 and later</compatibility>

<summary>

<note type="warning"><title>Warning</title>

<p>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.</p>

</note>

<p>This submodule of <module>mod_session</module> provides support for the

storage of user sessions within a SQL database using the

<module>mod_dbd</module> module.</p>

<p>Sessions can either be <strong>anonymous</strong>, where the session is

keyed by a unique UUID string stored on the browser in a cookie, or

<strong>per user</strong>, where the session is keyed against the userid of

the logged in user.</p>

<p>SQL based sessions are hidden from the browser, and so offer a measure of

privacy without the need for encryption.</p>

<p>Different webservers within a server farm may choose to share a database,

and so share sessions with one another.</p>

<p>For more details on the session interface, see the documentation for

the <module>mod_session</module> module.</p>

</summary>

<seealso><module>mod_session</module></seealso>

<seealso><module>mod_session_crypto</module></seealso>

<seealso><module>mod_session_cookie</module></seealso>

<seealso><module>mod_dbd</module></seealso>

<section id="dbdconfig"><title>DBD Configuration</title>

<p>Before the <module>mod_session_dbd</module> module can be configured to maintain a

session, the <module>mod_dbd</module> module must be configured to make the various database queries

available to the server.</p>

<p>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.</p>

<example><title>Sample DBD configuration</title>

<highlight language="config">

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 &gt; %lld)" selectsession

DBDPrepareSQL "delete from session where expiry != 0 and expiry &lt; %lld" cleansession

</highlight>

</example>

</section>

<section id="anonymous"><title>Anonymous Sessions</title>

<p>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.</p>

<p>To create a simple anonymous session and store it in a postgres database

table called <var>apachesession</var>, and save the session ID in a cookie

called <var>session</var>, configure the session as follows:</p>

<example><title>SQL based anonymous session</title>

<highlight language="config">

Session On

SessionDBDCookieName session path=/

</highlight>

</example>

<p>For more examples on how the session can be configured to be read

from and written to by a CGI application, see the

<module>mod_session</module> examples section.</p>

<p>For documentation on how the session can be used to store username

and password details, see the <module>mod_auth_form</module> module.</p>

</section>

<section id="peruser"><title>Per User Sessions</title>

<p>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.</p>

<p>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

<module>mod_auth_form</module>.</p>

<p>To create a simple per user session and store it in a postgres database

table called <var>apachesession</var>, and with the session keyed to the

userid, configure the session as follows:</p>

<example><title>SQL based per user session</title>

<highlight language="config">

Session On

SessionDBDPerUser On

</highlight>

</example>

</section>

<section id="housekeeping"><title>Database Housekeeping</title>

<p>Over the course of time, the database can be expected to start accumulating

expired sessions. At this point, the <module>mod_session_dbd</module> module

is not yet able to handle session expiry automatically.</p>

<note type="warning"><title>Warning</title>

<p>The administrator will need to set up an external process via cron to clean

out expired sessions.</p>

</note>

</section>

<directivesynopsis>

<name>SessionDBDCookieName</name>

<description>Name and attributes for the RFC2109 cookie storing the session ID</description>

<syntax>SessionDBDCookieName <var>name</var> <var>attributes</var></syntax>

<default>none</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context>

</contextlist>

<usage>

<p>The <directive>SessionDBDCookieName</directive> 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 <code>Set-Cookie</code> HTTP header.

</p>

<p>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.

</p>

<example><title>Cookie with attributes</title>

<highlight language="config">

Session On

SessionDBDCookieName session path=/private;domain=example.com;httponly;secure;version=1;

</highlight>

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SessionDBDCookieName2</name>

<description>Name and attributes for the RFC2965 cookie storing the session ID</description>

<syntax>SessionDBDCookieName2 <var>name</var> <var>attributes</var></syntax>

<default>none</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context>

</contextlist>

<usage>

<p>The <directive>SessionDBDCookieName2</directive> 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 <code>Set-Cookie2</code> HTTP header.

</p>

<p>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.

</p>

<example><title>Cookie2 with attributes</title>

<highlight language="config">

Session On

SessionDBDCookieName2 session path=/private;domain=example.com;httponly;secure;version=1;

</highlight>

</example>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SessionDBDCookieRemove</name>

<description>Control for whether session ID cookies should be removed from incoming HTTP headers</description>

<syntax>SessionDBDCookieRemove On|Off</syntax>

<default>SessionDBDCookieRemove On</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context>

</contextlist>

<usage>

<p>The <directive>SessionDBDCookieRemove</directive> flag controls whether the cookies

containing the session ID will be removed from the headers during request processing.</p>

<p>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.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SessionDBDPerUser</name>

<description>Enable a per user session</description>

<syntax>SessionDBDPerUser On|Off</syntax>

<default>SessionDBDPerUser Off</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context>

</contextlist>

<usage>

<p>The <directive>SessionDBDPerUser</directive> 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.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SessionDBDSelectLabel</name>

<description>The SQL query to use to select sessions from the database</description>

<syntax>SessionDBDSelectLabel <var>label</var></syntax>

<default>SessionDBDSelectLabel selectsession</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context>

</contextlist>

<usage>

<p>The <directive>SessionDBDSelectLabel</directive> directive sets the default select

query label to be used to load in a session. This label must have been previously defined using the

<directive module="mod_dbd">DBDPrepareSQL</directive> directive.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SessionDBDInsertLabel</name>

<description>The SQL query to use to insert sessions into the database</description>

<syntax>SessionDBDInsertLabel <var>label</var></syntax>

<default>SessionDBDInsertLabel insertsession</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context>

</contextlist>

<usage>

<p>The <directive>SessionDBDInsertLabel</directive> directive sets the default insert

query label to be used to load in a session. This label must have been previously defined using the

<directive module="mod_dbd">DBDPrepareSQL</directive> directive.</p>

<p>If an attempt to update the session affects no rows, this query will be called to insert the

session into the database.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SessionDBDUpdateLabel</name>

<description>The SQL query to use to update existing sessions in the database</description>

<syntax>SessionDBDUpdateLabel <var>label</var></syntax>

<default>SessionDBDUpdateLabel updatesession</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context>

</contextlist>

<usage>

<p>The <directive>SessionDBDUpdateLabel</directive> directive sets the default update

query label to be used to load in a session. This label must have been previously defined using the

<directive module="mod_dbd">DBDPrepareSQL</directive> directive.</p>

<p>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.</p>

</usage>

</directivesynopsis>

<directivesynopsis>

<name>SessionDBDDeleteLabel</name>

<description>The SQL query to use to remove sessions from the database</description>

<syntax>SessionDBDDeleteLabel <var>label</var></syntax>

<default>SessionDBDDeleteLabel deletesession</default>

<contextlist><context>server config</context>

<context>virtual host</context>

<context>directory</context>

<context>.htaccess</context>

</contextlist>

<usage>

<p>The <directive>SessionDBDDeleteLabel</directive> 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 <directive module="mod_dbd">DBDPrepareSQL</directive> directive.</p>

</usage>

</directivesynopsis>

</modulesynopsis>