在配置PPP验证时有PAP和CHAP的选择，其中PAP为明文传送用户名和口令，不安全。而CHAP则采用哈希值进行验证，口令不会在网上传送，所以安全性比较高。 CHAP认证也是CCNA课程PPP教学时所需掌握的基本配置，其配置如下： 拓扑： RA DTE--------DCE RB -------------------------------------- RA#conf t RA(config)#username RB password hello RA(config)#int s0 RA(config-if)#encap ppp RA(config-if)#ppp au chap RA(config-if)#end ------------------------------- Router(config)#host RB RB(config)#username RA password hello RB(config)#int s0 RB(config-if)#encap ppp RB(config-if)#ppp auth chap %LINK-3-UPDOWN: Interface Serial0, changed state to up %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to up ------------------------------------------------------ RA#sh int s0 Serial0 is up, line protocol is up -------第一层二层UP Hardware is HD64570 Internet address is 1.1.1.1/30 MTU 1500 bytes, BW 1544 Kbit, DLY 1000 usec, rely 255/255, load 1/255 Encapsulation PPP, loopback not set, keepalive set (10 sec) LCP Open -----------打开 Open: IPCP, CDPCP -----------打开 Last input 00:00:00, output 00:00:00, output hang never Last clearing of show interface counters never Queueing strategy: fifo