Apache ESME [Retired]

Wednesday April 13, 2011

LDAP-based Authentication with Apache ESME and Apache Directory Server

This blog was written by our new committer Vladimir Ivanov who implemented a feature that users have been wanting for a long time. 

In this blog, I'll discuss how container-managed authentication works with an LDAP server and how to connect and get additional information from it. I'll use Jetty and Apache Tomcat web servers with Apache Directory Server (ADS) 1.5.7 - a certified LDAPv3 compatible server. It is also possible to use different LDAP compatible server such as a 389 Directory Server or MS Active Directory.

An LDAP server is a directory service that contains objects organized in a hierarchical manner.

Apache Directory Server (ADS)

The ADS project page provides a detailed server installation and configuration guide, but here are the basic steps: during the installation, the default server instance will be created. The configuration settings for this instance are defined in the server.xml file as Spring bean definitions. Below is an excerpt from the configuration file that was used for this blog.


First of all, it is necessary to create a new partition:




<jdbmPartition id="lester" suffix="dc=lester,dc=org" />


Ports that LDAP server will use are specified as tcpTransport elements:

<ldapServer id="ldapServer"








<tcpTransport address="" port="10389" nbThreads="8" backLog="50" enableSSL="false"/>

<tcpTransport address="localhost" port="10636" enableSSL="true"/>



The local path to the directory containing LDIF files should also be specified:

<apacheDS id="apacheDS">




Other configuration settings were left unchanged.

Now It is time to create the directory structure. I used the popular open source tool JXplorer for this task.

It is possible to export the directory structure from the JXplorer tool to the LDIF file — directory content in text format. Let's review the generated file.


Below is a record list beginning from the top. Note that each record has specific set of object classes defined in this schema. Each object class defines specific set of attributes, for example, person class defines Surname (sn) and Given Name (givenName) attributes. One object class can extend another, for example organizationalPerson class extends person class. top is a superclass for all other classes.

Domain lester.org is the root of this hierarchy:

dn: dc=lester,dc=org

objectClass: extensibleObject

objectClass: domain

objectClass: top

dc: lester

The Organizational Unit esme is placed one level lower:

dn: ou=esme,dc=lester,dc=org

objectClass: organizationalUnit

objectClass: top

ou: esme

The Organizational Unit Groups resides under the esme Organizational Unit:

dn: ou=Groups,ou=esme,dc=lester,dc=org

objectClass: organizationalUnit

objectClass: top

ou: Groups

There is only one group esme-users on the lowest level of the hierarchy and it has the vivanov user (specified by a full path) as a unique member:

dn: cn=esme-users,ou=Groups,ou=esme,dc=lester,dc=org

objectClass: groupOfUniqueNames

objectClass: top

cn: esme-users

ou: Groups

uniqueMember: uid=vivanov,ou=Users,ou=esme,dc=lester,dc=org

The Organizational Unit Users resides under the esme organizational unit:

dn: ou=Users,ou=esme,dc=lester,dc=org

objectClass: organizationalUnit

objectClass: top

ou: Users

The user vivanov and its corresponding attributes are defined on the lowest level of the hierarchy:

dn: uid=vivanov,ou=Users,ou=esme,dc=lester,dc=org

objectClass: organizationalPerson

objectClass: person

objectClass: uidObject

objectClass: inetOrgPerson

objectClass: top

cn: vivanov

givenName: Vladimir

mail: vivanov@lester.org

ou: Users

sn: Ivanov

telephoneNumber: +7 111 222 33 44

uid: vivanov

userPassword:: cXdlcnR5

There is also a special user with administrative rights: uid=admin,ou=system (default password: secret) defined in system schema. It was used to connect to ADS from JXplorer.

Those were all basic steps necessary to configure ADS for purpose of this b log. Let's move to the configuration of the web servers.


Before digging into the configuration details specific for each web server, let's review the common properties used to connect to the LDAP server.

First of all, it is necessary to specify the hostname / ip address and the port of our LDAP server — localhost:10389, as well as the credentials for an account that has rights to perform search operation and get attributes for users and roles in a directory tree. The special admin user described in previous section was also used for this purpose in this blog. Sometimes anonymous access is also permitted.

The next set of properties, user base and group base, specify the base context with which to lookup users and groups. For our configuration web server will search users under ou=Users,ou=esme,dc=lester,dc=org and groups under ou=Groups,ou=esme,dc=lester,dc=org paths in the directory tree accordingly.

The user id and role name attributes specify the prefix for user/group search filter. In our example, it has the uid value for users and the cn value for groups.

The uniqueMember attribute is used to check whether the user belongs to the specified group.

Now it is time to review the configuration for each of the web servers.

Note: The required lift-ldap dependency has been already included in pom.xml.


In order to configure Jetty to use LDAP server, two additional Maven dependencies: jetty-plus and jetty-ldap-jaas should be added to the pom.xml file. Configuration of maven-jetty-plugin includes the following steps: set the JAASUserRealm as an user realm implementation and specify the ldaploginmodule as the login module name. It is also necessary to set the system property java.security.auth.login.config with the ldap-loginModule.conf value:





















<userRealm implementation="org.mortbay.jetty.plus.jaas.JAASUserRealm">













The file ldap-loginModule.conf is placed under the ESME_ROOT/server folder. It specifies login module implementation class - LdapLoginModule as well as LDAP-specific connection properties:


ldaploginmodule {

org.mortbay.jetty.plus.jaas.ldap.LdapLoginModule required




















Note that for some environments forceBindingLogin attribute must also be set to true.


The only required change in the Tomcat's server.xml configuration file (compared to the changes described in the last blog) is a different realm - JNDIRealm. This realm is used to connect to LDAP server and search users/groups:



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



connectionURL="ldap://localhost:10389" debug="99"









LDAPVendor and ESMELdap.properties file

The web server is now configured to perform CMA. But the Servlet API makes only the user principal available for application. In order to fill ESME user's profile, additional attributes such as firstname, lastname and email are needed. We will use LDAP server to retrieve these attributes. Let's review changes in UserAuth.scala, specifically in ContainerManagedAuthModule object:


To connect to the LDAP server from application first of all, it is necessary to create aq subclass of net.lift.ldap.LDAPVendor class:

object myLdapVendor extends LDAPVendor

All LDAP-specific connection properties are placed into a resource bundle — plaintext property file with key-value pairs. It is possible to get property values by key with the S.? method:

def myLdap : LDAPVendor = {

val ldapSrvHost = S.?("ldap.server.host")

val ldapSrvPort = S.?("ldap.server.port")

val ldapSrvBase = S.?("ldap.server.base")

val ldapSrvUsrName = S.?("ldap.server.userName")

val ldapSrvPwd = S.?("ldap.server.password")

val ldapSrvAuthType = S.?("ldap.server.authType")

val ldapSrvReferral= S.?("ldap.server.referral")

val ldapSrvCtxFactory = S.?("ldap.server.initial_context_factory")

The next step is to configure the LDAPVendor subclass with these values:

myLdapVendor.configure(Map("ldap.url" -> "ldap://%s:%s".format(ldapSrvHost, ldapSrvPort),

"ldap.base" -> ldapSrvBase,

"ldap.userName" -> ldapSrvUsrName,

"ldap.password" -> ldapSrvPwd,

"ldap.authType" -> ldapSrvAuthType,

"referral" -> ldapSrvReferral,

"ldap.initial_context_factory" -> ldapSrvCtxFactory))



The method getAttrs takes the username as a parameter and returns a map of [attribute name / list of attribute values] pairs (attribute in LDAP might contain more than one value) for this user. Let's review the method definition. It is possible to get attributes for user with LDAPVendor.attributesFromDn() method. It takes the distinguished name as a parameter, so it is necessary to append the prefix and the user base from the property file to the username to construct it. Note that the attributesFromDn method returns javax.naming.directory.Attributes therefore the interfaces from javax.naming.directory package must be imported correctly:

import _root_.javax.naming.directory.{Attributes, Attribute => Attr}

The shorthand Attr is used for the javax.naming.directory.Attribute because the scala.xml.Attribute trait has already been imported and placed in scope.

Then attribute's id and values are used to populate the result map.

The getAttrs method definition is shown below:

def getAttrs(who : String) : Map[String, List[String]] = {


val uidPrefix = S.?("ldap.uidPrefix")

val userBase = S.?("ldap.userBase")


var attrsMap = Map.empty[String, List[String]]

val dn = "%s=%s,%s".format(uidPrefix, who, userBase)


val attrs : Attributes = myLdap.attributesFromDn(dn)

if (attrs != null) {

val allAttrs = attrs.getAll();

if (allAttrs != null) {

while(allAttrs.hasMore()) {

val attribute = allAttrs.next().asInstanceOf[Attr];

var attrValues = List.empty[String]

for(i <- 0 until attribute.size()) {

attrValues ::= attribute.get(i).toString


attrsMap += (attribute.getID() -> attrValues)






The last step is to modify the performInit method. First of all, it is necessary to check if LDAP is enabled as configured in the property file. Then the values for attributes givenName, sn and mail are extracted from the map, returned via the getAttrs method call and then used to populate User instance.

def performInit(): Unit = {


val usr = User.createAndPopulate.nickname(username).saveMe

//find and save additional attributes in LDAP if It is enabled

val ldapEnabled = S.?("ldap.enabled")

if(ldapEnabled.toBoolean) {

val ldapAttrs = getAttrs(username)

val firstName = ldapAttrs("givenName").head

val lastName = ldapAttrs("sn").head

val mail = ldapAttrs("mail").head





The ESMELdap property file is shown below. It essentially resembles connection properties in web server configuration files that we have seen previously.

ESMELdap.properties file

#This flag specifies whether LDAP should be used


# Hostname or IP of LDAP server


# Port of LDAP server


# Base DN from the LDAP Server


# User that has access to LDAP server to perform search operations


# Password for user above


# Authentication type


# Referral


# Initial context factory class


# Prefix for user to whom additional LDAP attributes belong, for example 'uid' or 'sAMAccountName'


# User base DN for user to whom additional LDAP attributes belong


The last thing that must be done is to tell Lift where to look for the ESMELdap.properties file. The list of resource file names is assigned to LiftRules.resourceNames var in Boot.scala:


LiftRules.resourceNames = "ESMELdap" :: "ESMECustom" :: "ESMEBase" :: "ESMEUI" :: Nil


We have just configured both web servers - Jetty and Tomcat - to perform authentication and authorization via LDAP. We have also improved ContainerManagedAuthModule to get additional attributes for authenticated user from LDAP with Lift LDAP API.


1. Apache Directory Server: http://directory.apache.org/apacheds/1.5/

2. Jxplorer: http://jxplorer.org/

3. Jetty login modules: http://docs.codehaus.org/display/JETTY/JAAS


4. Tomcat user realms: http://tomcat.apache.org/tomcat-6.0-doc/realm-howto.html

5. Lift API: http://scala-tools.org/mvnsites/liftweb-2.3/

Thursday April 07, 2011

Container-Managed Authentication with Apache ESME: Part 1

Part 1: Performing authentication with plaintext/xml user-role mapping

This blog was written by our new committer Vladimir Ivanov who implemented a feature that users have been wanting for a long time. 


Apache ESME currently supports two different authentication schemes: when user credentials are stored in the database and via OpenID.  Corporate users, however, might be interested in container-managed authentication (CMA) — because this scheme supports integration with enterprise services such as LDAP and Single Sign-On. In the first part of this blog,  I'll explain how ESME-based applications can use CMA and how to configure two popular web servers- Apache Tomcat and Jetty - with simple user-role mapping. In the second part, I'll describe LDAP integration to perform CMA and how get additional user attributes via the Lift LDAP API.

ContainerManagedAuthModule: The necessary code changes

A new authentication module ContainerManagedAuthModule was introduced to hook into the container-managed authentication process. First of all, it was registered along with the other authentication modules:






All authentication modules should extend the AuthModule trait:

object ContainerManagedAuthModule extends AuthModule

Currently, the list with security role (group) names is also defined in the source code:

  val rolesToCheck = List(



It is also possible to get the list of roles from some external source, for example, from a property file or a LDAP.

The method moduleName defines the name for the new auth module. This value acts as a discriminator and will be stored in the DB:

  def moduleName: String = "cm"

After the container finishes the authentication and authorization phases, it is  neccessary to hook into the normal user processing to save the user data. This task is performed in the performInit method:

def performInit(): Unit = {

CMA must be applied to a specific URL, for example /cm/login, so it is necessary to append a partial function to LiftRules.dispatch to perform the neccessary operations:

    LiftRules.dispatch.append {

      case Req("cm" :: "login" :: Nil, _, _) =>  {

        val from = "/"

Note: The majority of necessary steps to further utilize this new auth method have already been desribed in the Lift Wiki.

In short, it is neccessary to unwrap the javax.servlet.http.HttpServletRequest object to get the username and role names. If a user has one of the specified roles, the module should attempt to find an existing user with the same nickname which previously has logged in via this module. If such a user hasn't been found, a new User is created.  The last step is to save the userId in the HTTP session via User.logUserIn method call.

        S.request match {

          case Full(req) => {

            val httpRequest: HTTPRequest = req.request

            val hrs = httpRequest.asInstanceOf[HTTPRequestServlet]

            val hsr: HttpServletRequest = hrs.req

            val username : String = hsr.getRemoteUser


              val currentRoles = rolesToCheck.filter(hsr.isUserInRole(_))

              if(currentRoles.size == 0) {

                info("No roles have been found")


              } else {

                currentRoles.map(cr => {

                (for {

                    user <- UserAuth.find(By(UserAuth.authKey, username),

                                          By(UserAuth.authType, moduleName)).flatMap(_.user.obj) or

                    User.find(By(User.nickname, username))

                  } yield user) match {

                    case Full(user) => {



                    case _ => {

                      val usr = User.createAndPopulate.nickname(username).saveMe

                      //find and save additional attributes in LDAP if it's enabled











Now it's time to set-up the configuration for the CMA. All configuration settings for a Java EE web application (ESME is based on the Lift web framework, so it's packaged as a WAR file), including security settings, are defined in the web.xml file:


For this example, we will use form-based authentication:




Next, the login and error pages are specified.






Then, the security-role name, which any authenticated user must have for successful authorization, is defined:

    <!-- Security roles referenced by this web application -->


      <description>An authenticated ESME user</description>



And finally it is necessary to configure the mapping between the security role and the URL which is associated with the new authentication module:

  <!-- Secured resources -->




        <description>Secured page for forcing the container to request login</description>







The login page contains a form with specific action attributes and two input fields:






    <body id="cm_login">

        <form method="POST" action="j_security_check">

          Username: <input type="text" name="j_username"/><br>

          Password: <input type="password" name="j_password"/><br>

          <input type="submit"/>




Let's move on to the web server configuration for the next steps. We must define the users for our web application as well as mapping between these users and the security role that is specified in the web.xml file. I'll show how to configure simple user-role mapping for two popular web servers — Jetty and Tomcat.


The HashUserRealm implementation is used to specify the user-role mapping in the properties file for Jetty. The maven-jetty-plugin has been already included in the Maven project file pom.xml for the ESME application, so it is possible to configure Jetty in the plugin configuration section:









                        <userRealm implementation="org.mortbay.jetty.security.HashUserRealm">







The format for this property file has the following form: username: password [,rolename ...].

An example is shown below:


cmuser: cmuser, esme-users

That's it. Now Jetty is configured for CMA. Execute mvn clean jetty-run command to start Jetty and type http://localhost:8080/cm/login URL in your browser. You should see the form containing the username and password fields. Now try to log in with the user with the id cmuser.


The configuration of Tomcat web server is very similar to that of Jetty, except that the user-role mapping is specified in a XML file.  The MemoryUserDatabaseFactory implementation is used to define the mapping file.  The corresponding realm UserDatabaseRealm is also specified in the server.xml configuration file:



    <!-- Editable user database that can also be used by

         UserDatabaseRealm to authenticate users


    <Resource name="UserDatabase" auth="Container"


              description="User database that can be updated and saved"


              pathname="conf/tomcat-users.xml" />



      <Realm className="org.apache.catalina.realm.UserDatabaseRealm"


Below is an example of the user-role mapping definition in the tomcat-users.xml file which is usually located in the  tomcat/conf directory.



  <role rolename="esme-users"/>

  <user name="cmuser" password="cmuser" roles="esme-users"/>


Now it's neccessary to package the WAR file with the mvn clean package command and deploy it to Tomcat either via maven plugin or in Tomcat's administrative console. Then proceed to the following URL:


The login form should be displayed.


In this part of the blog, I've covered the new authentication module, application and server configuration and simple user-role mapping. In the next part, I'll show how to configure Tomcat to use LDAP for CMA and get additional attributes for the authenticated user.


1. Lift Wiki - How to use Container Managed Security : http://www.assembla.com/wiki/show/liftweb/How_to_use_Container_Managed_Security

2. Jetty HashUserRealm: http://jetty.codehaus.org/jetty/jetty-6/apidocs/org/mortbay/jetty/security/HashUserRealm.html

3. Tomcat Realms: http://tomcat.apache.org/tomcat-6.0-doc/realm-howto.html

4. Java EE 5 Tutorial – Securing Web Applications: http://download.oracle.com/javaee/5/tutorial/doc/bncas.html



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