DACS_AUTOLOGIN_SSL(8)					     DACS Web Services Manual					     DACS_AUTOLOGIN_SSL(8)

NAME

       dacs_autologin_ssl - use an SSL client certificate to automatically obtain DACS credentials

SYNOPSIS

       dacs_autologin_ssl [dacsoptions[1]]

DESCRIPTION

       This program is part of the DACS suite.

       The dacs_autologin_ssl CGI program, in conjunction with appropriate DACS configuration and a valid SSL client certificate, can be used for
       user-transparent DACS authentication. A user is not prompted for a username or password, and no user-visible sign-on procedure takes place.

       At present, the program merely acts as glue to indirectly invoke dacs_authenticate(8)[2]. Any valid X.509 certificate can be used for this
       purpose, including a self-signed certificate. Please refer to the OpenSSL[3] documentation for additional information about certificates.

       This program can be used to automatically and transparently authenticate a user that has been issued an SSL client certificate. When an
       unauthenticated user is denied access to a DACS-wrapped resource, she can be automatically authenticated and redirected back to the
       resource without any user input or action. This assumes that the client certificate is sent automatically by the browser and that no
       additional user prompting is needed by the authenticating jurisdiction. For redirection to the original resource to work properly. the
       original request must have used the GET method.

	   Note
	   The cert style of authentication must be configured when dacs_autologin_ssl is being used as described. See dacs_authenticate(8)[4].

OPTIONS

       Only the standard dacsoptions[1] command line arguments are recognized.

   Web Service Arguments
       dasc_autologin_ssl understands the following CGI arguments.

       DACS_ERROR_URL
	   When dacs_autologin_ssl is invoked as a result of DACS event handling, DACS_ERROR_URL is automatically passed to it by dacs_acs(8)[5]
	   and represents the original URL to which access was denied. In typical use, dacs_autologin_ssl is configured as the handler for a
	   dacs_acs 902 error code (NO_AUTH, "Authentication by DACS is required").  dacs_autologin_ssl then invokes dacs_authenticate. If DACS
	   authentication is successful, dacs_authenticate ordinarily issues a browser redirect to the value of DACS_ERROR_URL and a cookie
	   bearing the credentials are set in the browser (but see the NOREDIRECT argument). This argument is optional; if not provided, the
	   jurisdiction's configured post-authentication action will occur.

       NOREDIRECT
	   If this optional argument is present (its value is immaterial), dacs_autologin_ssl instructs dacs_authenticate to not issue a browser
	   redirect to the value of DACS_ERROR_URL.

       AUTH_JURISDICTION
	   If this optional argument is present, it gives the name of the jurisdiction at which authentication should take place. By default,
	   dacs_authenticate is invoked at the same jurisdiction as dacs_autologin_ssl.

       CERT_NAME_ATTR
	   This optional argument explicitly names the attribute in the certificate from which to set USERNAME. The default value is
	   SSL_CLIENT_S_DN_CN. It is an error if the specified attribute name does not exist. Giving the value of CERT_NAME_ATTR as the empty
	   string results in the empty string being passed as the value of USERNAME.

EXAMPLE

       A typical use of dacs_autologin_ssl is to transparently authenticate a user via his SSL client certificate.

       In the DACS configuration file, dacs.conf, jurisdiction EXAMPLE is configured as follows (this excerpt from a configuration file uses
       fictitious domain names):

	   <Jurisdiction uri="example.com">

	   JURISDICTION_NAME "EXAMPLE"

	   ACS_ERROR_HANDLER "NO_AUTH https://example.com/cgi-bin/dacs/dacs_autologin_ssl"

	   <!-- Authenticate using an SSL certificate. -->
	   <Auth id="cert">
	   URL "https://example.com/cgi-bin/dacs/local_cert_authenticate"
	   STYLE "cert"
	   CONTROL "sufficient"
	   CERT_CA_PATH "/usr/local/apache2.2/conf/ssl.crt"
	   CERT_NAME_ATTR "SSL_CLIENT_S_DN_CN"
	   </Auth>

	   </Jurisdiction>

       Assume the following access control rule applies to the request:

	   <acl_rule status="enabled">
	     <services>
	       <service url_pattern='/foo.html'/>
	     </services>

	     <rule order="allow,deny">
	       <allow>
		 user("auth")
	       </allow>
	     </rule>
	   </acl_rule>

       The preceding configuration results in the following behaviour. An unauthenticated user accessing foo.html (https://example.com/foo.html)
       is denied access because the rule governing that web page tests for authentication and no credentials are sent with the request. As a
       result, the ACS_ERROR_HANDLER[6] directive causes the user to be redirected to dacs_autologin_ssl, which redirects the user to
       dacs_authenticate, passing arguments as necessary.

       dacs_authenticate then invokes local_cert_authenticate[4], passing it the client's certificate. The certificate is validated and a username
       is extracted from it and mapped to a valid DACS username.

       If authentication succeeds, DACS credentials for the jurisdiction EXAMPLE are generated. These credentials are returned to the browser
       within a cookie and the browser is redirected to the value of DACS_ERROR_URL (recall that DACS_ERROR_URL was passed to dacs_autologin_ssl
       by dacs_acs when the 902 handler was invoked and was forwarded to dacs_authenticate). In this example the user is redirected to
       https://example.com/foo.html. Given the rule above, this time the user's request for foo.html will be granted.

       dacs_autologin_ssl may also be used as the target of an explicit authentication link. For example:

	   <a href="https://example.com/cgi-bin/dacs/dacs_autologin_ssl?
	   AUTH_JURISDICTION=EXAMPLE&
	   DACS_ERROR_URL=https://example.com/cgi-bin/dacs/dacs_current_credentials">Login</a>

       Following the link should result in the user being authenticated and redirected to the specified URL.

DIAGNOSTICS

       The program exits 0 if everything was fine, 1 if an error occurred.

SEE ALSO

       dacs_authenticate(8)[2], dacs_acs(8)[5], dacs.conf(5)[7], autologin(8)[8]

AUTHOR

       Distributed Systems Software (www.dss.ca[9])

COPYING

       Copyright2003-2012 Distributed Systems Software. See the LICENSE[10] file that accompanies the distribution for licensing information.

NOTES

	1. dacsoptions
	   http://dacs.dss.ca/man/dacs.1.html#dacsoptions

	2. dacs_authenticate(8)
	   http://dacs.dss.ca/man/dacs_authenticate.8.html

	3. OpenSSL
	   http://www.openssl.org

	4. dacs_authenticate(8)
	   http://dacs.dss.ca/man/dacs_authenticate.8.html#local_cert_authenticate

	5. dacs_acs(8)
	   http://dacs.dss.ca/man/dacs_acs.8.html

	6. ACS_ERROR_HANDLER
	   http://dacs.dss.ca/man/dacs.conf.5.html#ACS_ERROR_HANDLER

	7. dacs.conf(5)
	   http://dacs.dss.ca/man/dacs.conf.5.html

	8. autologin(8)
	   http://dacs.dss.ca/man/autologin.8.html

	9. www.dss.ca
	   http://www.dss.ca

       10. LICENSE
	   http://dacs.dss.ca/man/../misc/LICENSE

DACS 1.4.27b							    10/22/2012						     DACS_AUTOLOGIN_SSL(8)