R1
Router>en
Router#conf t
Router(config)#ho r1
r1(config)#line co 0
r1(config-line)#logg sy
r1(config-line)#exec-tim 0 0
r1(config-line)#exit
r1(config)#no ip domain-loo
r1(config)#in s0/0
r1(config-if)#ip ad 192.168.10.1 255.255.255.0
r1(config-if)#no sh
r1(config-if)#encapsulation ppp
r1(config-if)#ppp authentication pap
r1(config-if)#ppp pap sent-username r2 pa no
r1(config)#username r1 password yes
R2
Router>en
Router#conf t
Router(config)#ho r2
r2(config)#line co 0
r2(config-line)#logg sy
r2(config-line)#exec-tim 0 0
r2(config-line)#exit
r2(config)#no ip domain-loo
r2(config)#in s0/0
r2(config-if)#ip ad 192.168.10.2 255.255.255.0
r2(config-if)#no sh
r2(config-if)#encapsulation ppp
r2(config-if)#ppp authentication pap
r2(config-if)#ppp pap sent-username r1 pa yes
r2(config)#username r2 password no
r2(config)#int s0/1
r2(config-if)#ip ad 192.168.10.3 255.255.255.0
r2(config-if)#no sh
r2(config-if)#encapsulation ppp
r2(config-if)#ppp authentication chap
r2(config)#username r3 password hello
R3
Router>en
Router#conf t
Router(config)#ho r3
r3(config)#line co 0
r3(config-line)#logg sy
r3(config-line)#exec-tim 0 0
r3(config-line)#exit
r3(config)#no ip domain-loo
r3(config)#int s0/1
r3(config-if)#ip ad 192.168.10.4 255.255.255.0
r3(config-if)#no sh
r3(config-if)#encapsulation ppp
r3(config-if)#ppp authentication chap
r3(config)#username r2 password hello