code: @Override
  	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
  
  		if (!(request instanceof HttpServletRequest)){
  			chain.doFilter(request, response);
  			return;
  		}
  
  		HttpServletRequest httpServletRequest = ((HttpServletRequest) request);
  		HttpServletResponse httpServletResponse = ((HttpServletResponse) response);
  
  		if(WebUIConfig.getInstance().getAuthentication().isAuthenticationEnabled()
  				&& !isAuthAction(httpServletRequest.getRequestURI())) {
  			// Means current page is protected by authorization
  
  			if (isAuthorized(httpServletRequest)) {
  				httpServletRequest.setAttribute("mskIsAuthorized", true); // Enables logout button
  			} else {
  
  				// Reset auth cookie for cases it was corrupted (encryption key is changed or something like that)
  				Cookie authCookie = new Cookie(AuthConstants.AUTH_COOKIE_NAME, "");
  				authCookie.setMaxAge(0);
  				httpServletResponse.addCookie(authCookie);
  
  				// User be redirected to this url after success authorization
  				httpServletRequest.getSession().setAttribute(
  						AuthConstants.LOGIN_REFER_PAGE_SESSION_ATTR_NAME,
  						httpServletRequest.getRequestURL().toString()
  				);
  				// Redirect to login page
  				httpServletResponse.sendRedirect("mskSignIn");
  				return;
  
  			}
  
  		}
  
  		super.doFilter(request, response, chain);
  
  	}
docs: Checks user authorization if it enabled in config