Computer Freaks: July 2014

CAS client and Server configuration | Java

How to set up a CAS Server/Client Web application

The full form of CAS is Central Authentication Service. What it does is that, it provides authentication service to the client applications.

Well, I will describe my experience with the web applications. I started making simple web applications and build some functionality in it. Then I added security to the same application by creating login pages, storing passwords in the database and validating them against the user provided ones. Now, working in a IT-Company, where there are many applications. Normally the user who had taken three applications will have to have three different accounts in the web applications of the same company. Now, With the concept of cas, what you could do it build the authentication web application in one place, and point all you other web applications to use this service to authenticate.

Now lets move the place where we set up CAS 4.0 with Cas client version 3.2.1.
Jasig CAS is the most used version.

What do you need to do.

Install your cas Server

- Download CAS from this location
- Extract it, go inside the folder cas-server-webapp and build the project with maven.(mvn clean package)
- Copy it in the webapps folder of your Tomcat.
- (Optional) If you want to configure your tomcat to https, follow this link, otherwise configure your cas to work with non-secure version by
changing the p:cookieSecure="true" to p:cookieSecure="false" under /WEB-INF/spring-configuration/ticketGrantingTicketCookieGenerator.xml of cas Server
- Start your tomcat, and browse to the location [http://localhost:8080/cas or https://localhost:8443/cas](if you have not changed the port of tomcat)

Install your cas Client

- Download the cas client dependencies from this location
- Run the pom.xml and add the jars created in the java web application
- Create a simple web application with web.xml, if you don't have your own application.
- Copy these libraries to the lib folder of WEB-INF
cas-client-core-3.1.1.jar (from cas-client 3.1.1)
commons-logging-1.1.jar (from cas-client 3.1.1)
xercesImpl.jar (from Apache Xerces release 2.9.1)
xml-apis.jar (from Apache Xerces release 2.9.1)
xmlsec-1.3.0.jar (from cas-client 3.1.1)
- Add the following filters in your web.xml. Change the locations


<filter>

  <filter-name>CAS Authentication Filter</filter-name>

  <filter-class>org.jasig.cas.client.authentication.AuthenticationFilter</filter-class>

  <init-param>

   <param-name>casServerLoginUrl</param-name>

   <param-value>http://localhost:8080/cas/login</param-value>

  </init-param>

  <init-param>

   <param-name>serverName</param-name>

   <param-value>http://localhost:8080</param-value>

  </init-param>

  <init-param>

   <param-name>renew</param-name>

   <param-value>false</param-value>

  </init-param>

  <init-param>

   <param-name>gateway</param-name>

   <param-value>false</param-value>

  </init-param>

 </filter>



 <filter>

  <filter-name>CAS Validation Filter</filter-name>

  <filter-class>org.jasig.cas.client.validation.Cas20ProxyReceivingTicketValidationFilter</filter-class>

  <init-param>

   <param-name>casServerUrlPrefix</param-name>

   <param-value>http://localhost:8080/cas/</param-value>

  </init-param>

  <init-param>

   <param-name>serverName</param-name>

   <param-value>http://localhost:8080</param-value>

  </init-param>

  <init-param>

   <param-name>proxyCallbackUrl</param-name>

   <param-value>http://localhost:8080/webappcas2/proxyCallback</param-value>

  </init-param>

  <init-param>

   <param-name>proxyReceptorUrl</param-name>

   <param-value>/webappcas2/proxyCallback</param-value>

  </init-param>

 </filter>



 <filter>

  <filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>

  <filter-class>org.jasig.cas.client.util.HttpServletRequestWrapperFilter</filter-class>

 </filter>



 <filter>

  <filter-name>CAS Assertion Thread Local Filter</filter-name>

  <filter-class>org.jasig.cas.client.util.AssertionThreadLocalFilter</filter-class>

 </filter>



 <!-- ************************* -->



<!-- Sign out not yet implemented -->

<!-- 

 <filter-mapping>

  <filter-name>CAS Single Sign Out Filter</filter-name>

  <url-pattern>/*</url-pattern>

 </filter-mapping>

-->



 <filter-mapping>

  <filter-name>CAS Authentication Filter</filter-name>

  <url-pattern>/*</url-pattern>

 </filter-mapping>



 <filter-mapping>

  <filter-name>CAS Validation Filter</filter-name>

  <url-pattern>/*</url-pattern>

 </filter-mapping>

  

 <filter-mapping>

  <filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>

  <url-pattern>/*</url-pattern>

 </filter-mapping>



 <filter-mapping>

  <filter-name>CAS Assertion Thread Local Filter</filter-name>

  <url-pattern>/*</url-pattern>

 </filter-mapping>



 <filter-mapping>

  <filter-name>CAS Validation Filter</filter-name>

  <url-pattern>/proxyCallback</url-pattern> 

 </filter-mapping>

- My web.xml look like this


<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

 xmlns="http://java.sun.com/xml/ns/javaee"

 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"

 id="WebApp_ID" version="3.0">

 <display-name>CasClientSimple</display-name>



 <filter>

  <filter-name>CAS Authentication Filter</filter-name>

  <filter-class>org.jasig.cas.client.authentication.AuthenticationFilter</filter-class>

  <init-param>

   <param-name>casServerLoginUrl</param-name>

   <param-value>https://localhost:1443/cas/login</param-value>

  </init-param>

  <init-param>

   <param-name>serverName</param-name>

   <param-value>https://localhost:2443</param-value>

  </init-param>

  <init-param>

   <param-name>renew</param-name>

   <param-value>false</param-value>

  </init-param>

  <init-param>

   <param-name>gateway</param-name>

   <param-value>false</param-value>

  </init-param>

 </filter>



 <filter>

  <filter-name>CAS Validation Filter</filter-name>

  <filter-class>org.jasig.cas.client.validation.Cas20ProxyReceivingTicketValidationFilter</filter-class>

  <init-param>

   <param-name>casServerUrlPrefix</param-name>

   <param-value>https://localhost:1443/cas/</param-value>

  </init-param>

  <init-param>

   <param-name>serverName</param-name>

   <param-value>https://localhost:2443</param-value>

  </init-param>

  <init-param>

   <param-name>proxyCallbackUrl</param-name>

   <param-value>https://localhost:1443/cas/proxyCallback</param-value>

  </init-param>

  <init-param>

   <param-name>proxyReceptorUrl</param-name>

   <param-value>/cas/proxyCallback</param-value>

  </init-param>

 </filter>



 <filter>

  <filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>

  <filter-class>org.jasig.cas.client.util.HttpServletRequestWrapperFilter</filter-class>

 </filter>



 <filter>

  <filter-name>CAS Assertion Thread Local Filter</filter-name>

  <filter-class>org.jasig.cas.client.util.AssertionThreadLocalFilter</filter-class>

 </filter>



 <!-- ************************* -->



 <!-- Sign out not yet implemented -->

 <!-- <filter-mapping> <filter-name>CAS Single Sign Out Filter</filter-name>

  <url-pattern>/*</url-pattern> </filter-mapping> -->



 <filter-mapping>

  <filter-name>CAS Authentication Filter</filter-name>

  <url-pattern>/*</url-pattern>

 </filter-mapping>



 <filter-mapping>

  <filter-name>CAS Validation Filter</filter-name>

  <url-pattern>/*</url-pattern>

 </filter-mapping>



 <filter-mapping>

  <filter-name>CAS HttpServletRequest Wrapper Filter</filter-name>

  <url-pattern>/*</url-pattern>

 </filter-mapping>



 <filter-mapping>

  <filter-name>CAS Assertion Thread Local Filter</filter-name>

  <url-pattern>/*</url-pattern>

 </filter-mapping>



 <filter-mapping>

  <filter-name>CAS Validation Filter</filter-name>

  <url-pattern>/proxyCallback</url-pattern>

 </filter-mapping>



 <welcome-file-list>

  <welcome-file>index.html</welcome-file>

  <welcome-file>index.htm</welcome-file>

  <welcome-file>index.jsp</welcome-file>

  <welcome-file>default.html</welcome-file>

  <welcome-file>default.htm</welcome-file>

  <welcome-file>default.jsp</welcome-file>

 </welcome-file-list>

</web-app>

Edit your deployerConfigContext.xml, registeredservices list of CAS-server


<bean class="org.jasig.cas.services.RegexRegisteredService"

              p:id="0" p:name="HTTP and IMAP"

     p:description="Allows HTTP(S) and IMAP(S) protocols"

              p:serviceId="^(https?|imaps?)://.*"

     p:evaluationOrder="10000001"

     p:enabled="true"

     p:allowedToProxy="true"

     p:ssoEnabled="true"

  />

- Now try browsing your web application. You will be directed to the cas url.
- If you are redirected to wrong url, try reconfiguring the corresponding url in your client, restart the tomcat and try again.

Some common errors you could run into

- Authentication validatin exception
- You have not configured the Registered services list in deployerconfigcontext.xml of the cas server.
- SSL validation exception
- you probably have not registered the certificate.cer in your jre's cacerts file.

References:
- http://www.javaroots.com/2013/05/configure-cas-server-and-client-in-java.html
- http://jasig.github.io/cas/4.0.0/installation/Service-Management.html

SSL tomcat

The problem I was facing was of CAS implementation. I had to test the implementation in my local environment. The CAS implementation is such that it will require HTTPS protocol to work properly. So I have to configure my tomcat for SSL.

How Certificate works

First the server needs a private key which it keeps itself
Then it generates the certificate(which also contains the public key, i think)
on first page request, server sends certificate(user has to accept and trust it if it is not signed by trusted associations)
Then a SSL handshake is made (server has private key and the user has the public key, each can decrypt others message)
REF: http://security.stackexchange.com/questions/20803/how-does-ssl-tls-work

The steps you should follow to configure a Security certificate to your tomcat are as follows.

Create a self signed certificate(keystore, eg common.jks)
Create a certificate file from the keystore(eg. common.cer).
Add the certificate to the trust store of java.

I was using same instance of jdk for CAS-Server and Client application so I did not have to create two certificates and add them to the trust stores of two JDK's. I used single certificate for both the application.

1. To create a new keystore from scratch, containing a single self-signed Certificate, execute the following from a terminal command line:

"%JAVA_HOME%\bin\keytool" -genkey -alias tomcat -keyalg RSA -keystore D:\Tomcats\common.jks

Note: creates file named abc.jks

/*
2. To create a CSR as follows

"%JAVA_HOME%\bin\keytool" -keystore "D:\Tomcats\common.jks" -certreq -alias tomcat -keyalg rsa -file "D:\Tomcats\common.csr"

*/

3. OR (export the generated certificate to a file)

"%JAVA_HOME%\bin\keytool" -export -alias tomcat -storepass changeit -file "D:\Tomcats\common.cer" -keystore "D:\Tomcats\common.jks"

4. To create the trust store file cacerts.jks and add the certificate to the truststore

"%JAVA_HOME%\bin\keytool" -import -v -trustcacerts -alias tomcat -file "D:\Tomcats\common.cer" -keystore "D:\Tomcats\cacerts.jks" -keypass changeit

    - to add the certificate to the trust of java

"%JAVA_HOME%\bin\keytool" -import -alias tomcat  -file "D:\Tomcats\common.cer" -keystore  "%JAVA_HOME%\jre\lib\security\cacerts"

5. Delete an already present certificate

keytool -delete -alias tomcat -keystore "D:\Tomcats\common.jks" -storepass changeit

After the certificate stuff, you have to configure the <tomcat-home>/conf/server.xml to use the certificate just generated. Its optional to keep or comment out the http port but its better to comment it out because allowing both https port and http port would slow down your application and consume more resources.

<?xml version='1.0' encoding='utf-8'?>
<!--
  Licensed to the Apache Software Foundation (ASF) under one or more
  contributor license agreements.  See the NOTICE file distributed with
  this work for additional information regarding copyright ownership.
  The ASF licenses this file to You 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.
-->
<!-- Note:  A "Server" is not itself a "Container", so you may not
     define subcomponents such as "Valves" at this level.
     Documentation at /docs/config/server.html
 -->
<Server port="1005" shutdown="SHUTDOWN">
  <!-- Security listener. Documentation at /docs/config/listeners.html
  <Listener className="org.apache.catalina.security.SecurityListener" />
  -->
  <!--APR library loader. Documentation at /docs/apr.html , commented by rajan-->
  <!--<Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />-->
  <!--Initialize Jasper prior to webapps are loaded. Documentation at /docs/jasper-howto.html -->
  <Listener className="org.apache.catalina.core.JasperListener" />
  <!-- Prevent memory leaks due to use of particular java/javax APIs-->
  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />
  <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />
  <Listener className="org.apache.catalina.core.ThreadLocalLeakPreventionListener" />

  <!-- Global JNDI resources
       Documentation at /docs/jndi-resources-howto.html
  -->
  <GlobalNamingResources>
    <!-- Editable user database that can also be used by
         UserDatabaseRealm to authenticate users
    -->
    <Resource name="UserDatabase" auth="Container"
              type="org.apache.catalina.UserDatabase"
              description="User database that can be updated and saved"
              factory="org.apache.catalina.users.MemoryUserDatabaseFactory"
              pathname="conf/tomcat-users.xml" />
  </GlobalNamingResources>

  <!-- A "Service" is a collection of one or more "Connectors" that share
       a single "Container" Note:  A "Service" is not itself a "Container",
       so you may not define subcomponents such as "Valves" at this level.
       Documentation at /docs/config/service.html
   -->
  <Service name="Catalina">

    <!--The connectors can use a shared executor, you can define one or more named thread pools-->
    <!--
    <Executor name="tomcatThreadPool" namePrefix="catalina-exec-"
        maxThreads="150" minSpareThreads="4"/>
    -->


    <!-- A "Connector" represents an endpoint by which requests are received
         and responses are returned. Documentation at :
         Java HTTP Connector: /docs/config/http.html (blocking & non-blocking)
         Java AJP  Connector: /docs/config/ajp.html
         APR (HTTP/AJP) Connector: /docs/apr.html
         Define a non-SSL HTTP/1.1 Connector on port 8080
    -->
   <!-- <Connector port="1111" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="1443" />
    -->
    <!-- A "Connector" using the shared thread pool-->
    <!--
    <Connector executor="tomcatThreadPool"
               port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />
    -->
    <!-- Define a SSL HTTP/1.1 Connector on port 8443
         This connector uses the JSSE configuration, when using APR, the
         connector should be using the OpenSSL style configuration
         described in the APR documentation -->
    <!--
    <Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true"
               maxThreads="150" scheme="https" secure="true"
               clientAuth="false" sslProtocol="TLS" />
    -->
 <!--<Connector port="1443" maxThreads="150" scheme="https" 
  secure="true" SSLEnabled="true" keystoreFile="conf/ssoServer.jks" 
  keystorePass="changeit" clientAuth="false" keyAlias="tomcat" 
  sslProtocol="TLS"/>
 -->
 
 <Connector port="1443" maxThreads="150" scheme="https" 
    secure="true" SSLEnabled="true" keystoreFile="D:/Tomcat/common.jks" 
    keystorePass="changeit" clientAuth="false" keyAlias="tomcat" sslProtocol="TLS"/>
    <!-- Define an AJP 1.3 Connector on port 8009 -->
    <Connector port="1009" protocol="AJP/1.3" redirectPort="1443" />


    <!-- An Engine represents the entry point (within Catalina) that processes
         every request.  The Engine implementation for Tomcat stand alone
         analyzes the HTTP headers included with the request, and passes them
         on to the appropriate Host (virtual host).
         Documentation at /docs/config/engine.html -->

    <!-- You should set jvmRoute to support load-balancing via AJP ie :
    <Engine name="Catalina" defaultHost="localhost" jvmRoute="jvm1">
    -->
    <Engine name="Catalina" defaultHost="localhost">

      <!--For clustering, please take a look at documentation at:
          /docs/cluster-howto.html  (simple how to)
          /docs/config/cluster.html (reference documentation) -->
      <!--
      <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"/>
      -->

      <!-- Use the LockOutRealm to prevent attempts to guess user passwords
           via a brute-force attack -->
      <Realm className="org.apache.catalina.realm.LockOutRealm">
        <!-- This Realm uses the UserDatabase configured in the global JNDI
             resources under the key "UserDatabase".  Any edits
             that are performed against this UserDatabase are immediately
             available for use by the Realm.  -->
        <Realm className="org.apache.catalina.realm.UserDatabaseRealm"
               resourceName="UserDatabase"/>
      </Realm>

      <Host name="localhost"  appBase="webapps"
            unpackWARs="true" autoDeploy="true">

        <!-- SingleSignOn valve, share authentication between web applications
             Documentation at: /docs/config/valve.html -->
        <!--
        <Valve className="org.apache.catalina.authenticator.SingleSignOn" />
        -->

        <!-- Access log processes all example.
             Documentation at: /docs/config/valve.html
             Note: The pattern used is equivalent to using pattern="common" -->
        <Valve className="org.apache.catalina.valves.AccessLogValve" directory="logs"
               prefix="localhost_access_log." suffix=".txt"
               pattern="%h %l %u %t &quot;%r&quot; %s %b" />

      </Host>
    </Engine>
  </Service>
</Server>

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