Configuring tomcat to authenticate using windows Active Directory

<Realm className="org.apache.catalina.realm.JNDIRealm" debug="99"

           connectionURL="ldap://youradsserver:389/"
           alternateURL="ldap://youradsserver:389/"         
           userRoleName="member"
           userBase="cn=Users,dc=yourdomain"
           userPattern="cn={0},cn=Users,dc=yourdomain"
           roleBase="cn=Users,dc=yourdomain"
           roleName="cn"
           roleSearch="(member={0})"
           roleSubtree="false"
           userSubtree="true" 
   />
and define the role in the tomcat-users.xml and the web.xml of your application
edit webapp_root/WEB_INF/Web.xml file as follows:
<security-constraint>
   <display-name>your web app display name</display-name>
   <web-resource-collection>
     <web-resource-name>Protected Area</web-resource-name>
     <url-pattern>*.jsp</url-pattern>
     <url-pattern>*.html</url-pattern>
     <url-pattern>*.xml</url-pattern>
   </web-resource-collection>
   <auth-constraint>
     <role-name>yourrolname(ADS Group)</role-name>
   </auth-constraint>
 </security-constraint>
 <login-config>
   <auth-method>FORM</auth-method>
   <form-login-config>
     <form-login-page>/login.jsp</form-login-page>
     <form-error-page>/error.jsp</form-error-page>
   </form-login-config>
 </login-config>
 <security-role>
   <description>your role description</description>
   <role-name>yourrolename(i.e ADS group)</role-name>
 </security-role>