R1(config-if)#encapsulation ppp
When a ppp session is stablished the neighbors exchange their L3 addresses. Allowing connectivity between devices L2 connected but in different subnets.
If you want to avoid of learning the neighbor route:
R1(config-if)#no peer neighbor-route
Uses clear text authentication that could be sniffed .
Inside the interface
ppp authentication pap <----- in the side who initializate the communication, not needed in both sides
username X password Y <-----the username and password that the other side must send.
In the other side
Configure the username:
ppp pap sent-username X password YPAP example:
R1:
R1(configure)#interface Serial3/1
R1(configure-if)# ip address 192.168.1.1 255.255.255.0
R1(configure-if)# encapsulation ppp
R1(configure-if)# serial restart-delay 0
R1(configure-if)# ppp authentication pap
end
R1(configure)#username Paquito password 0 Chocolatero
R3:
R3(configure)#interface Serial3/3
R3(configure-if)# ip address 10.0.0.1 255.255.255.0
R3(configure-if)# encapsulation ppp
R3(configure-if)# serial restart-delay 0
R3(configure-if)# ppp pap sent-username Paquito password 0 Chocolatero
end
PPP Chap authentication:
Uses challenges MD5, not plain text password, it is a secure authentication.
Configuration:
R1(configure)#ppp authentication chap <----who iniciates the authentication
R1(configure-if)#username x password password y
In the other side:
R1(configure)#username z password y
x= the name of the router of the other side
y= the password, that must match
z= the name of the router of the other side
The password allowed could be in clear( username x password y), using type 7(username x password7 y) but not using secret(username x secret y).
At interface level:
ppp chap hostname w
default password <---never used in the side with ppp authentication chap
ppp chap password X <----default for all the sessions
It also could be configured at interface level.
CHAP example:
R3:
R3(config)#interface Serial3/3R2:
R3(config-if)# ip address 10.0.0.1 255.255.255.0
R3(config-if)# encapsulation ppp
R3(config-if)# serial restart-delay 0
end
R3(config)#username R2 password 0 Tomatito
R2(config)#interface Serial3/1
R2(config-if)# ip unnumbered Loopback0
R2(config-if)# encapsulation ppp
R2(config-if)# serial restart-delay 0
R2(config-if)# ppp authentication chap
end
R2(config)#username R3 password 0 Tomatito
