cas/src/main/java/org/springframework/security/cas/web/CasAuthenticationFilter.java
protected boolean requiresAuthentication(final HttpServletRequest request,
			final HttpServletResponse response) {
		final boolean serviceTicketRequest = serviceTicketRequest(request, response);
		final boolean result = serviceTicketRequest || proxyReceptorRequest(request)
				|| (proxyTicketRequest(serviceTicketRequest, request));
		if (logger.isDebugEnabled()) {
			logger.debug("requiresAuthentication = " + result);
		}
		return result;
	}
protected boolean requiresAuthentication(final HttpServletRequest request,
			final HttpServletResponse response) {
		final boolean serviceTicketRequest = serviceTicketRequest(request, response);
		final boolean result = serviceTicketRequest || proxyReceptorRequest(request)
				|| (proxyTicketRequest(serviceTicketRequest, request));
		if (logger.isDebugEnabled()) {
			logger.debug("requiresAuthentication = " + result);
		}
		return result;
	}
Overridden to provide proxying capabilities.