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==================================================================== MOD_AUTH_CAS 1.0.9 README ==================================================================== Apache CAS Authentication Module ==================================================================== LICENSE ==================================================================== Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. ==================================================================== INTRODUCTION ==================================================================== The purpose of this module is to allow an Apache web server to interact with an authentication server that conforms to the CAS version 1 or 2 protocol as specified by Yale/JA-SIG. At the time of this writing, the CAS protocol specification is here: http://www.ja-sig.org/products/cas/overview/protocol/index.html ==================================================================== NEW FEATURES AND FUNCTIONS IN THIS RELEASE ==================================================================== * mod_auth_cas 1.0.9 is now licensed under the Apache 2 License. All future versions will be released under this license until further notice. * mod_auth_cas 1.0.8 and prior should be considered as available under the Apache 2 License or the GPLv3 license. ==================================================================== BUG FIXES ==================================================================== * Included a patch by Chris Adams of Yale University to prevent segfaults when parsing a corrupted XML cache file. ==================================================================== KNOWN LIMITATIONS ==================================================================== These limitations are known to exists in this release of the software: * CAS Proxy Validation is not implemented in this version. * CAS Ticket Validation can only be performed over an SSL connection. The CAS protocol does not explicitly require this, but to not do so leaves this system open to a man-in-the-middle attack. * CAS single sign out is currently not functional and disabled. It is only safe to use in the case where all requests are GET and not POST (the module inadvertently 'eats' some content of the POST request while determining if it should process it as a SAML logout request). * Reports of slow performance on some systems (particularly virtual machines) have been reported. This is related to the entropy that is gathered when creating a session cookie for the end user. To combat this, there are 3 solutions. The first is to upgrade the version of the Apache Portable Runtime on your system to >= 1.3.0. In that version, entropy is gathered from a nonblocking source. The second method would be to install a package such as rng-tools and feed random data from /dev/urandom to /dev/random("-r /dev/urandom"). The last way is to reduce the size of the CASCookieEntropy setting, reducing the demand on the pool. ==================================================================== GETTING STARTED ==================================================================== SOFTWARE DEPENDENCIES -------------------------------------------------------------------- The module was built and tested on the following libraries/versions: OpenSSL - 0.9.8c Apache Portable Runtime - 1.2.8 Apache Portable Runtime Utilities - 1.2.7 Apache Web Server - 2.2.3 Additionally, GNU Make and the auto* tools are necessary for building mod_auth_cas. Compatibility with other versions will depend on those other libraries. INSTALLATION INSTRUCTIONS -------------------------------------------------------------------- Ensure that the follow files are in the working directory: mod_auth_cas.c mod_auth_cas.h COMPILE INSTRUCTIONS -------------------------------------------------------------------- Use the APache eXtenSion tool (APXS) to compile and install this object as a dynamically shared object (DSO), by either: apxs -i -c mod_auth_cas.c or apxs2 -i -c mod_auth_cas.c depending on your Linux distribution. This release of mod_auth_cas includes support for autoconf. Note that you must use GNU Make - other Make implementations may work, but are untested and not recommended. Use the standard commands below to compile and install: ./configure; make; make install configure can take an optional --with-apxs=/path/to/apxs argument to specify the path to your APXS binary. CONFIGURING THE SOFTWARE -------------------------------------------------------------------- First, you must tell Apache to load the module. In your httpd.conf, add: LoadModule auth_cas_module /path/to/mod_auth_cas.so Then, in the location(s) you want to protect, use the following directive: AuthType CAS Be sure to set authorization parameters in the locations you are protecting(e.g. 'require valid-user', 'require group foo') The following are valid configuration options and their default: Valid Server/VirtualHost Directives ----------------------------------- Directive: CASVersion Default: 2 Description: The version of the CAS protocol to adhere to (1 or 2). This affects whether Gateway mode is available and how the CAS validation response is parsed. Directive: CASDebug Default: Off Description: Enable or disable debugging mode for troubleshooting. Directive: CASValidateServer Default: On Description: If set to 'On', mod_auth_cas will validate that the certificate presented by the server specified in CASLoginURL is both signed by the Certificate Authority specified in CASCertificatePath and that the hostname matches the Common Name of the certificate. Directive: CASValidateDepth Default: 9 Description: This directive will set the maximum depth for chained certificate validation. The default (according to OpenSSL documentation) is 9. Directive: CASAllowWildcardCert Default: Off Description: This directive determines whether a wildcard certificate can be trusted to verify the CAS server. For instance, if the CAS server presents a certificate for *.example.com and the hostname portion of the CASValidateURL is 'cas.login.example.com', this directive (if enabled) will accept that certificate. Directive: CASCertificatePath Default: /etc/ssl/certs/ Description: The path to the X509 certificate of the Certificate Authority for the server in CASLoginURL and CASValidateURL. This may be either a file, or a directory containing the certificate files linked to by their hashed names. Directive: CASLoginURL Default: NULL Description: The URL to redirect users to when they attempt to access a CAS protected resource and do not have an existing session. The 'service', 'renew', and 'gateway' parameters will be appended to this by mod_auth_cas if necessary. Include 'http[s]://...' Directive: CASValidateURL Default: NULL Description: The URL to use when validating a ticket presented by a client in the HTTP query string (ticket=...). Must include 'https://' and must be an HTTPS URL. Directive: CASProxyValidateURL Default: NULL Description: The URL to use when performing a proxy validation. This is currently an unimplemented feature, so setting this will have no effect. Directive: CASCookiePath Default: /dev/null Description: When users first authenticate to mod_auth_cas with a valid service ticket, a local session is established. Information about this session (the username, time of creation, last activity time, the resource initially requested, and whether or not the credentials were renewed) is stored in this directory. This location should be writable by the web server ONLY. Any user that can write to this location can falsify authentication information by creating a fake data file. NOTE : Some distributions purge the contents of /tmp/ on a reboot, including user created directories. This will prevent mod_auth_cas from storing cookie information until that directory is created. To avoid this, try using a different location, such as /var/cache/apache2/mod_auth_cas/ Directive: CASCookieEntropy Default: 32 Description: When creating a local session, this many random bytes are used to create a unique session identifier. Using large values for this field may result in delays when generating session IDs if not enough entropy is available. Directive: CASTimeout Default: 7200 (2 hours) Description: This is the hard limit, in seconds, for a mod_auth_cas session (whether it is idle or not). When a session has reached this age and a new request is made, the user is redirected to the CASLoginURL to obtain a new service ticket. When this new ticket is validated, they will be assigned a new mod_auth_cas session. Directive: CASIdleTimeout Default: 3600 (1 hour) Description: This is a limit, in seconds, of how long a mod_auth_cas session can be idle. When a request comes in, if it has been inactive for CASIdleTimeout seconds, the user is redirected to the CASLoginURL to obtain a new service ticket. Directive: CASCacheCleanInterval Default: 1800 (30 minutes) Description: This is the minimum amount of time that must pass inbetween cache cleanings. When a new ticket is issued, or when an expired session is presented, the time of the last cache clean is compared against this value. If CASCacheCleanInterval seconds have passed since the last cleaning, then all files in CASCookiePath are examined and if they have expired, they are removed. This is merely to prevent the file system from becoming excessively cluttered. Directive: CASCookieDomain Default: NULL Description: Specify the value for the 'Domain=' parameter in the Set-Cookie header. Directive: CASCookieHttpOnly Default: Off Description: Set the optional 'HttpOnly' flag for cookies issues by mod_auth_cas. This parameter may break RFC compliance since HttpOnly is not defined in RFC 2109. See http://msdn2.microsoft.com/en-us/library/ms533046.aspx for more information. Please note this feature is not honored by all browsers. Valid Directory/.htaccess Directives ------------------------------------ Directive: CASScope Default: Off Description: Use this directive with an argument as a relative path (e.g. /application/) to specify the scope for which a mod_auth_cas cookie is valid. This is beneficial to prevent additional round trips to the CAS server. Assume someone authenticates to /application/subdir/ and then browses to /application/ - without CASScope set, each request would result in a round trip to the CAS server and a new cookie being created (one for each directory). CASScope would set one cookie, which will be presented on access to both directories. Note that if someone accessed /application/ and then /application/subdir/ this would not be an issue, but that order of access can not be guaranteed. To disable this feature, the special argument 'Off' will return to per-directory cookie paths for this directory and subdirectories. Directive: CASRenew Default: Off Description: Use this directive with an argument as a relative path (e.g. /application/secure/ for http://www.example.com/application/secure/*) to force a user to renew their credentials when accessing that directory. The argument MUST be a relative path. To disable this requirement, the special argument 'Off' will disable this requirement for this directory and subdirectories. Directive: CASGateway Default: Off Description: Use this directive with an argument as a relative path (e.g. /application/insecure/ for http://www.example.com/application/insecure/*) to allow anonymous access to that directory. The argument MUST be a relative path. To disable this feature, the special argument 'Off' will reinstate the requirement for authentication. Directive: CASCookie Default: MOD_AUTH_CAS Description: The name of the cookie used to store the session ID over HTTP connections. It should be changed if it will interfere with the application protected by mod_auth_cas. Directive: CASSecureCookie Default: MOD_AUTH_CAS_S Description: The name of the cookie used to store the session ID over HTTPS connections. It should be changed if it will interfere with the application protected by mod_auth_cas. Directive: CASGatewayCookie Default: MOD_AUTH_CAS_G Description: The name of the cookie used to store whether or not the user has attempted to access this resource before. It should be changed if it will interfere with the application protected by mod_auth_cas. Directive: CASAuthNHeader Default: None Description: If enabled, this will store the user returned by CAS in an HTTP header accessible to your web applications. Directive: CASSSOEnabled Default: Off Description: If enabled, this activates support for Single Sign Out within the CAS protocol. Please note that this feature is currently experimental and may mangle POST data. ==================================================================== CONTRIBUTORS ==================================================================== Author: Phil Ames <modauthcas [at] gmail [dot] com> Designers: Phil Ames <modauthcas [at] gmail [dot] com> Matt Smith <matt [dot] smith [at] uconn [dot] edu> Portions of this module are based on code from a CAS module by Yale. See comments in mod_auth_cas.c ==================================================================== CONTACT INFORMATION AND WEBSITE ==================================================================== We welcome your feedback, suggestions and contributions. Contact us via email if you have questions, feedback, code submissions, and bug reports. ====================================================================