What is j_security_check?

Question

I am new to Java and servlet? I am trying to setup a form based authintication. in every example, I find that page is calling for j_security_check. Can anyone please give some light on j_security_check?
Thanks,

Answer 1

The following will help you SECURITY ENABLE Each and Every application.
You no longer need to redirect your application to the login page.
Implement the following class ...
package   com.x.webapp;
public class LoginFilter implements Filter {
    protected FilterConfig filterConfig = null;
    public void destroy() {
       filterConfig.getServletContext()
          .log(":: PostLoginFilter - destroy");
       filterConfig = null;
    public void doFilter(ServletRequest req, ServletResponse resp,
             FilterChain chain) throws ServletException, IOException {
       filterConfig.getServletContext()
          .log(":: PostLoginFilter - doFilter");
       chain.doFilter(req, resp);
    public void init(FilterConfig config) throws ServletException {
       filterConfig = config;
       filterConfig.getServletContext().log(":: PostLoginFilter - init");
The login.jsp page contains the following form -- DO NOT USE STRUTS or anything else.
Just copy the EXACT TEXT BELOW.
     <form method="post" action="/j_security_check">
          Userid: <input type="text" name="j_username">
          Password: <input type="password" name="j_password">
          <input type="submit" value="Login">
     </form>If you are really smart and know your way in and out of the deployment descriptors
and or config files (like struts-config.xml and validation.xml etc...), there
is nothing to prevent you from renaming the action, and nothing to prevent you from
rewriting the form using struts or something else !
web.xml has the following:
<filter>
    <filter-name>LoginFilter</filter-name>
    <display-name>PostLoginFilter</display-name>
    <filter-class>com.x.webapp.LoginFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>LoginFilter</filter-name>
    <url-pattern>/j_security_check</url-pattern>
</filter-mapping>
    <security-constraint>
          <display-name>TestApp Security Constraint</display-name>
          <web-resource-collection>
                <web-resource-name>Protected Area</web-resource-name>
                <!-- Define the context-relative URL(s) to be protected -->
                <url-pattern>/*</url-pattern>
                <!-- If you list http methods, only those methods are protected -->
                <http-method>DELETE</http-method>
                <http-method>GET</http-method>
                <http-method>POST</http-method>
               <http-method>PUT</http-method>
          </web-resource-collection>
          <auth-constraint>
               <!-- Anyone with one of the listed roles may access this area -->
               <role-name>standard</role-name>
          </auth-constraint>
     </security-constraint>
    <!-- Default login configuration uses form-based authentication -->
    <login-config>
      <auth-method>FORM</auth-method>
      <realm-name>Form-Based Authentication</realm-name>
      <form-login-config>
        <form-login-page>/WEB-INF/jsp/login.jsp</form-login-page>
        <form-error-page>/html/LoginFailure.html</form-error-page>
      </form-login-config>
    </login-config>
    <!-- Security roles referenced by this web application -->
    <security-role>
      <role-name>standard</role-name>
    </security-role>