Debugging PPP Authentication
To affectation the CHAP affidavit action as it occurs amid two routers in the network,
just use the command alter ppp authentication.
If your PPP encapsulation and affidavit are set up accurately on both routers and if
your usernames and passwords are all good, again the alter ppp affidavit command
will affectation achievement that looks like this:
d16h: Se0/0 PPP: Using absence alarm direction
1d16h: Se0/0 PPP: Treating affiliation as a committed line
1d16h: Se0/0 CHAP: O CHALLENGE id 219 len 27 from "Pod1R1"
1d16h: Se0/0 CHAP: I CHALLENGE id 208 len 27 from "Pod1R2"
1d16h: Se0/0 CHAP: O RESPONSE id 208 len 27 from "Pod1R1"
1d16h: Se0/0 CHAP: I RESPONSE id 219 len 27 from "Pod1R2"
1d16h: Se0/0 CHAP: O SUCCESS id 219 len 4
1d16h: Se0/0 CHAP: I SUCCESS id 208 len 4
But if you accept the username wrong, as we did ahead in the PPP affidavit failure
example in Figure 11.4, the achievement would attending article like this:
1d16h: Se0/0 PPP: Using absence alarm direction
1d16h: Se0/0 PPP: Treating affiliation as a committed line
1d16h: %SYS-5-CONFIG_I: Configured from animate by console
1d16h: Se0/0 CHAP: O CHALLENGE id 220 len 27 from "Pod1R1"
1d16h: Se0/0 CHAP: I CHALLENGE id 209 len 27 from "Pod1R2"
1d16h: Se0/0 CHAP: O RESPONSE id 209 len 27 from "Pod1R1"
1d16h: Se0/0 CHAP: I RESPONSE id 220 len 27 from "Pod1R2"
1d16h: Se0/0 CHAP: O FAILURE id 220 len 25 msg is "MD/DES analyze failed"
PPP with CHAP affidavit is a three-way authentication, and if the username and
passwords are not configured absolutely the way they should be, again the affidavit will fail
and the articulation will be down.