industry standard authentication procedures, such as password authentication protocol ( pap ), challenge handshake authentication protocol ( chap ) and calling line identifier ( cli ) provide organizations with the ability to filter out unwanted and unqualified entries, while granting correctly authenticated users easy access 工业标准认证过程,如口令认证协议(pap)、挑战握手协议(chap)和打入电话线认识器(cli)等给各单位提供了过滤掉无用或无资格入网的能力,同时给认证的用户提供正确方便的访问。