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Session Handling

Session Handling. Authentication and Security Joshua Scotton. Overview. Sessions Login and Authentication. Sessions. Tracking the User. Tracking the User. Cookies Store a unique identifier in a cookie for the website URL Rewriting Append a unique identifier to the end of each URL

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Session Handling

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  1. Session Handling Authentication and Security Joshua Scotton

  2. Overview • Sessions • Login and Authentication

  3. Sessions Tracking the User

  4. Tracking the User • Cookies • Store a unique identifier in a cookie for the website • URL Rewriting • Append a unique identifier to the end of each URL • Hidden Form Fields • <INPUT TYPE="HIDDEN" NAME="session" VALUE="...">

  5. Benefits • Customization • Adaptive Content • Adaptable Content • Security • Restrict areas of the site based on user • User login tracked using session • User Behaviour • Track page accesses • User Information • Store user settings and information

  6. javax.servlet.http.HttpSession • getAttribute(), getAttributeNames(), setAttribute(), removeAttribute() • These methods are used to set, get and remove objects from a user session • getId() • Every session created by the server has a unique 'id' associated with it in order to identify this session from other sessions. • getCreationTime() • Simple returns a long value indicating the date and time this session was created. • getLastAccessedTime() • Returns a long value indicating the last time user accessed any resource on this server. • getMaxInactiveInterval(), setMaxInactiveInterval() • Return and set the maximum inactive interval in seconds for this session respectively. • isNew() • Returns a boolean value indicating if the session is new. • invalidate() • Simply invalidates a session. Can be used for logout

  7. Sessions in Java • Most Java servers will use cookies if the browser supports them, but automatically revert to URL-rewriting when cookies are unsupported or explicitly disabled.

  8. Counter Example • Sessions can be accessed and managed by both Servlets and JSPs. • This can happen in combination as in the following demo.

  9. CounterBean public class CounterBean implements Serializable { private Integer count; public CounterBean() { super(); this.count = 0; } public Integer getCount() { return this.count; } public void setCount(Integer count) { this.count = count; } public void incrementCount() { this.count++; } }

  10. UpdateCounter.jsp <jsp:useBean id="counter" class="webdev.examples.sessions.CounterBean" scope="session"/> <p> The counter was: <%= counter.getCount() %> </p> <% counter.incrementCount(); %> <p> The counter is now: <%= counter.getCount() %> </p>

  11. UpdateCounterServlet PrintWriter out = response.getWriter(); HttpSession session = request.getSession(true); CounterBean counter; if(session.isNew()) { counter = new CounterBean(); session.setAttribute("counter", counter); } counter = ((CounterBean)session.getAttribute("counter")); counter.incrementCount(); out.println("Counter now: " + counter.getCount()); out.close();

  12. Login and Authentication Allowing Persistent Storage

  13. JSP and Servlet Authentication • A user accesses a protected page • If the user is authenticated and has permission to access the page then the resource is made available. Otherwise a login page is shown • If the name and password cannot be authenticated then an error is shown

  14. Security Setup • User/Group Database • Access Control List (ACL) • Login Page

  15. Principals and Roles • A Principal is a named entity, commonly representing an individual or corporation. • Principal’s can fill one or more Roles. • Resources can be protected by associating them with Roles. • Principals and Roles are similar to Users and Groups in Linux.

  16. /WEB_INF/web.xmlThe ACL of Java <web-app> ... <security-constraint> <web-resource-collection> <web-resource-name>Protected Page</web-resource-name> <url-pattern> /secretPage.jsp </url-pattern> </web-resource-collection> <auth-constraint> <role-name>employee</role-name> </auth-constraint> </security-constraint> <security-role> <role-name>employee</role-name> </security-role> <web-app>

  17. /WEB_INF/web.xml • <url-pattern>/members/*</url-pattern> • More than one url-pattern in the web-resource-collection

  18. HttpServletRequest Security Methods • Principal getUserPrincipal() • Returns a reference to a java.security.Principal • booleanisUserInRole(String) • Determines whether a user is in a role, specified by the string argument • String getRemoteUser() • Returns the username that was used for login

  19. ServletRequest Security Methods • String getAuthType() • Returns the authentication type: BASIC, SSL, or null • booleanisSecure() • Returns true if the connection is HTTPS • String getScheme() • Scheme represents transport mechanism: http, https...

  20. Authentication Types • Basic authentication • Form-based authentication • Digest authentication • SSL and client certificate authentication

  21. Authentication Type in /WEB_INF/web.xml <web-app> ... <login-config> <auth-method>BASIC</auth-method> <realm-name>Basic Authentication Example</realm-name> </login-config> ... </web-app>

  22. Realms • A realm is a database of usernames and passwords • It also contains a list of roles associated with each user • Realms are specific to the server being used

  23. Tomcat Realms • JDBCRealm - Accesses authentication information stored in a relational database, accessed via a JDBC driver. • DataSourceRealm - Accesses authentication information stored in a relational database, accessed via a named JNDI JDBC DataSource. • JNDIRealm - Accesses authentication information stored in an LDAP based directory server, accessed via a JNDI provider. • UserDatabaseRealm - Accesses authentication information stored in an UserDatabase JNDI resource, which is typically backed by an XML document (conf/tomcat-users.xml). • MemoryRealm - Accesses authentication information stored in an in-memory object collection, which is initialized from an XML document (conf/tomcat-users.xml). • JAASRealm - Accesses authentication information through the Java Authentication & Authorization Service (JAAS) framework.

  24. Configuring a Realm • <Realm className="... class name for this implementation" ... other attributes for this implementation .../> • Serverwide - conf/server.xml • Per Webapp – META-INF/context.xml

  25. In Memory Realm Context.xml <?xml version="1.0" encoding="UTF-8"> <Context> <Realm className="org.apache.catalina.realm.MemoryRealm" /> </Context>

  26. Default Tomcat User List • $TOMCAT_HOME/conf/tomcat-users.xml <tomcat-users> <role rolename="tomcat"/> <role rolename="role1"/> <user username="tomcat" password="tomcat“ roles="tomcat"/> <user username="both" password="tomcat“ roles="tomcat,role1"/> <user username="role1" password="tomcat“ roles="role1"/> </tomcat-users>

  27. Example – members.jsp • members.jsp • web.xml • context.xml

  28. Example – logout.jsp <p>User '<%= request.getRemoteUser() %>' has been logged out.</p> <% session.invalidate(); %>

  29. Form-based Authentication • The login form associated with the security constraint is sent to the client and the URL path triggering the authentication is stored by the container. • The user is asked to fill out the form, including the username and password fields. • The client posts the form back to the server. • The container attempts to authenticate the user using the information from the form. • If authentication fails, the error page is returned using either a forward or a redirect, and the status code of the response is set to 200. • If authentication succeeds, the authenticated user's principal is checked to see if it is in an authorized role for accessing the resource. • If the user is authorized, the client is redirected to the resource using the stored URL path.

  30. Form-based Authentication • Create custom login page with the following form fields: • j_username • The name of the username field • j_password • The name of the password field • j_security_check • The login form's action <form method='post' action='j_security_check'> <input type='text' name='j_username'> <input type='password' name='j_password'> </form>

  31. Form-based Auth in web.xml <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>

  32. Form Based Login Example

  33. Storing Authentication Details in a Database • Use a JDBC Database Realm • Create table of usernames and passwords • Create table of usernames and roles • Column name for the username must be the same in both tables

  34. org.apache.catalina.realm.JDBCRealm • connectionName • connectionPassword • connectionURL • driverName • roleNameCol • userCredCol • userNameCol • userRoleTable • userTable • http://tomcat.apache.org/tomcat-3.3-doc/JDBCRealm-howto.html

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