- dacs_signout [m[blue]dacsoptionsm]
The dacs_signout web service is invoked from a web browser to cause one or more sets of DACS credentials for the m[blue]current federationm, stored as HTTP cookies, to be removed from the browser. This is done by replacing one or more existing cookies with cookies that have expired. The effect is that the user agent signs out (logs off) identities previously obtained through m[blue]dacs_authenticate(8)m or any other DACS authentication method. A DACS-enabled portal will typically provide users with a link or web page form to invoke this service.
By default, all credentials are removed, but credentials can be selected for deletion based on a particular username (who the user was authenticated as) or a particular jurisdiction (the jurisdiction that performed that authentication).
Should copies of the selected credentials exist outside of the browser, they may still be valid; only the browser's copies are destroyed.
The m[blue]SIGNOUT_HANDLERm directive can optionally be used to specify where the user should be redirected before this service terminates, provided FORMAT does not select a variety of XML output (see m[blue]dacs.conf(5)m). If XML output is selected, a document conforming to m[blue]dacs_current_credentials.dtdm is returned.
Explicitly signing off using this web service is generally unnecessary because DACS credentials will either become invalid when their lifetime is reached (see m[blue]AUTH_CREDENTIALS_DEFAULT_LIFETIME_SECSm) or will be automatically deleted when the user's browser session terminates (or a session with a trusted servlet ends). A user can also sign off by deleting his browser's DACS cookies. Middleware can simply discard cookies.
As DACS credentials are relative to a particular federation of DACS servers, only those credentials that are associated with the federation of the DACS server that receives the service request will be affected by this service. This implies that a user who wants to explicitly sign out must do so for each federation in which he or she is currently authenticated.
Web Service Arguments
In addition to the m[blue]standard CGI argumentsm, dacs_signout understands the following CGI arguments:
- If present, all credentials associated with this username will be deleted. If not provided, the username in the credentials is immaterial.
- If present, all credentials associated with this jurisdiction (given as its m[blue]JURISDICTION_NAMEm) will be deleted. If not provided, the jurisdiction in the credentials is immaterial.
- This optional parameter is as described for the m[blue]dacs_authenticate(8)m service.
The optional parameters are used to delete only those credentials that match a particular username or jurisdiction (or both). If neither parameter is specified in the service request, all DACS cookies associated with the federation that receives the service request will be deleted.
The name matching method can be configured through the m[blue]NAME_COMPAREm directive.
DACS does not currently provide an inactivity timeout feature, but it may appear in a future release. One way to add it would be to take advantage of the m[blue]user trackingm capability, which can record all of a user's requests for DACS-wrapped services within a federation. By simply comparing the current time with the time stamp of the user's last service request, the user's idle time can be determined. If the idle time exceeds a configured maximum, m[blue]dacs_acs(8)m would consider the user's credentials to be invalid (effectively expired) and take appropriate action. A straightforward implementation would be a relatively simple enhancement to DACS; its main drawback, for those that enable it, is the extra performance hit incurred from user tracking and having to compute idle time during access control processing - whether this hit is significant will depend on your platforms, the configuration of your federation, and user activity patterns.
To signout from all identities in the EXAMPLE federation, a user would simply invoke a URL like:
To signout only from the identity EXAMPLE::FEDROOT:bobo, a URL like the following might be invoked:
To signout from only those identities in the EXAMPLE federation having a username component bobo, invoke a URL like:
This would signoff from EXAMPLE::FEDROOT:bobo and EXAMPLE::DSS:bobo, for instance.
The program exits 0 if everything was fine, 1 if an error occurred.
Distributed Systems Software (m[blue]www.dss.cam)
Copyright2003-2012 Distributed Systems Software. See the m[blue]LICENSEm file that accompanies the distribution for licensing information.
- current federation
- standard CGI arguments
- user tracking