1, Network topology

Two, PAP

2.1 PAP single authentication: R1 is the server, R2 is the client

R1 To configure:
R1>enable
R1#configure terminal
R1(config)#username jsxjs password adminjsxjs
R1(config)#interface s0/0
R1(config-if)#encapsulation ppp
R1(config-if)#ppp authentication pap
R2 To configure:
R2>enable
R2#configure terminal
R2(config)#interface s0/0
R2(config-if)#encapsulation ppp
R2(config-if)#ppp pap sent-username jsxjs password adminjsxjs

2.2 PAP two-way authentication: (the user name and password configured by both parties are different, of course, the user name and password of both parties can also be set)

R1 To configure:
R1>enable
R1#configure terminal
R1(config)#username jsxjs password adminjsxjs
R1(config)#interface s0/0
R1(config-if)#encapsulation ppp
R1(config-if)#ppp pap sent-username jlzz password adminjlzz
R1(config-if)#ppp authentication pap
R2 To configure:
R2>enable
R2#configure terminal
R2(config)#username jlzz password adminjlzz
R2(config)#interface s0/0
R2(config-if)#encapsulation ppp
R2(config-if)#ppp pap sent-username jsxjs password adminjsxjs
R2(config-if)#ppp authentication pap

Three, CHAP

3.1 CHAP one-way authentication: (R1 is the server, R2 is the client)

R1 To configure:
R1(config)#username jsxjs password adminjsxjs
R1(config)#interface s0/0
R1(config-if)#encapsulation ppp
R1(config-if)#ppp authentication chap
R2 To configure:
R2(config)#interface s0/0
R2(config-if)#encapsulation ppp
R2(config-if)#ppp chap hostname jsxjs
R2(config-if)#ppp chap password adminjsxjs

3.2 CHAP two-way authentication: (the user names and passwords of both parties are different here to show the difference between two-way authentication. You can also set the same user name and password)

R1 To configure:
R1(config)#username jsxjs password adminjsxjs
R1(config)#interface s0/0
R1(config-if)#encapsulation ppp
R1(config-if)#ppp authentication chap
R1(config-if)#ppp chap hostname jlzz
R1(config-if)#ppp chap password adminjlzz
R2 To configure:
R2(config)#username jlzz password adminjlzz
R2(config)#interface s0/0
R2(config-if)#encapsulation ppp
R2(config-if)#ppp authentication chap
R2(config-if)#ppp chap hostname jsxjs
R2(config-if)#ppp chap password adminjsxjs

3.3 mutual authentication of chap: (both parties set the user name of authentication as the hostname of the opposite device, and set the same password)

R1 To configure:
RTA(config)#username RTB password netscene.net
RTA(config)#interface s1/1
RTA(config-if)#encapsulation ppp
RTA(config-if)#ppp authentication chap 
R2 To configure:
RTB(config)#username RTA password netscene.net
RTB(config-if)#encapsulation ppp
RTB(config-if)#ppp authentication chap

Four, explain

PAP authentication uses plaintext to transmit user name and password in the network, which is less secure than CHAP authentication.