<div class="conteudo">
   <div id="container">

    <p:messages class="ui-messages-mensagem" id="msg" showDetail="true" autoUpdate="true" closable="true"/>
    <br></br>

    <div id="titulo_page">Área Restrita</div>
    <div id="login_box">
    <div id="logo_login">
    <h:graphicImage value="/RESOURCES/icons/login/icons_login.png" id="login_title" />
    </div>
    <div id="titulo_login">Login</div>
    <h:form id="formLogin" enctype="multipart/form-data">

    <p:panelGrid columns="2" class="withoutBorder" >
    <h:outputLabel id="info_login"> <h:graphicImage url="/RESOURCES/icons/login/icons_user.png" class="login_icon" /></h:outputLabel>
    <p:inputText value="#{login.usuario}" id="login" class="input-login"/>

    <h:outputLabel id="info_senha"> <h:graphicImage url="/RESOURCES/icons/login/icons_password.png" class="login_icon" /></h:outputLabel>
    <p:password value="#{login.password}" id="senha" class="input-login"/>

    <p:watermark for="login" value="Usuário"/>
    <p:watermark for="senha" value="Senha" />

    </p:panelGrid>
    <br/>

     <div>
     <p:commandButton id="btnEntrar" icon="ui-icon-unlocked" value="Entrar"
    action="#{login.logarNoSistema}" />

    </div>

HttpServletRequest request = (HttpServletRequest) req;
     HttpServletResponse response = (HttpServletResponse) resp;
     HttpSession session = request.getSession();

     FacesContext context = FacesContext.getCurrentInstance();

     String loginURI = request.getContextPath() + "/RESOURCES/paginas/login.xhtml";

     boolean loggedIn = session != null && session.getAttribute("user") != null;
     boolean loginRequest = request.getRequestURI().equals(loginURI);
     boolean resourceRequest = request.getRequestURI().startsWith(request.getContextPath() + ResourceHandler.RESOURCE_IDENTIFIER);
     boolean resourceRequestCSS = request.getRequestURI().contains("/RESOURCES/css");
     boolean resourceRequestIcons = request.getRequestURI().contains("/RESOURCES/icons");

     if (loggedIn || loginRequest || resourceRequest || resourceRequestCSS || resourceRequestIcons) {
         chain.doFilter(request, response);

     } else {
         response.sendRedirect(loginURI);    }
  }

<filter-mapping>

@Override
public void afterPhase(PhaseEvent arg0) {

 FacesContext facesContext = FacesContext.getCurrentInstance();
 if (!facesContext.getPartialViewContext().isAjaxRequest() || facesContext.getRenderResponse()) { // not ajax or too late
  return;
 }

  HttpServletRequest request = HttpServletRequest.class.cast(facesContext.getExternalContext().getRequest());

  if (request.getDispatcherType() == DispatcherType.FORWARD && getLoginPath().equals(request.getServletPath())) { // isLoginRedirection()
        final String redirect = facesContext.getExternalContext().getRequestContextPath() + request.getServletPath();
        try {
            facesContext.getExternalContext().redirect(redirect);
           // facesContext.addMessage(null, new FacesMessage(FacesMessage.SEVERITY_ERROR,
            //      "Sessão Expirada", "Entre novamente com seu login e senha"));


        } catch (IOException e) {

        }
    }
}