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

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.

AUTHOR

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

COPYING

       Copyright © 2003-2012 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 1.4.40                                        02/19/2019                              DACS_AUTOLOGIN_SSL(8)