Specifications

5-7
Cisco AS5x00 Case Study for Basic IP Modem Services
11/24/1999
Section 5 Configuring PPP and Authentication
Testing Asynchronous PPP Connections
5.2 Failed PPP Negotiation Debug and Troubleshooting
Failed authentication is a common occurrence. Misconfigured or mismatched usernames and passwords
create error messages in debug output.
The following example shows that the username
maddog
does not have permission to dial into the NAS.
The NAS does not have a local username configured for this user. To fix the problem, use the
username
name
password
password
command to add the username to the local AAA database in the NAS:
*Sep 24 13:11:28.964: AAA/MEMORY: create_user (0x63E43558) user='maddog' ruser='
' port='Async1/2/10' rem_addr='4089548211/51121' authen_type=PAP service=PPP priv=1
*Sep 24 13:11:28.964: AAA/AUTHEN/START (3281080218): port='Async1/2/10' list=''
action=LOGIN service=PPP
*Sep 24 13:11:28.964: AAA/AUTHEN/START (3281080218): using "default" list
*Sep 24 13:11:28.964: AAA/AUTHEN (3281080218): status = UNKNOWN
*Sep 24 13:11:28.964: AAA/AUTHEN/START (3281080218): Method=LOCAL
*Sep 24 13:11:28.964: AAA/AUTHEN (3281080218): User not found, end of method list
*Sep 24 13:11:28.964: AAA/AUTHEN (3281080218): status = FAIL
*Sep 24 13:11:28.964: As1/2/10 PAP: O AUTH-NAK id 1 len 32 msg is "Password
validation failure"
*Sep 24 13:11:28.964: AAA/MEMORY: free_user (0x63E43558) user='maddog' ruser=''
port='Async1/2/10' rem_addr='4089548211/51121' authen_type=PAP service=PPP priv=1
The following example shows an invalid password. Notice that the same error messages are used for
username failure—“Password validation failure.”
*Sep 24 13:13:59.032: AAA/MEMORY: create_user (0x63E9846C) user='dude' ruser=''
port='Async1/2/11' rem_addr='4089548211/51121' authen_type=PAP service=PPP priv=
1
*Sep 24 13:13:59.032: AAA/AUTHEN/START (3032205297): port='Async1/2/11' list=''
action=LOGIN service=PPP
*Sep 24 13:13:59.032: AAA/AUTHEN/START (3032205297): using "default" list
*Sep 24 13:13:59.032: AAA/AUTHEN (3032205297): status = UNKNOWN
*Sep 24 13:13:59.032: AAA/AUTHEN/START (3032205297): Method=LOCAL
*Sep 24 13:13:59.032: AAA/AUTHEN (3032205297): status = FAIL
*Sep 24 13:13:59.032: As1/2/11 PAP: O AUTH-NAK id 1 len 32 msg is "Password vali
dation failure"
*Sep 24 13:13:59.036: AAA/MEMORY: free_user (0x63E9846C) user='dude' ruser='' po
rt='Async1/2/11' rem_addr='4089548211/51121' authen_type=PAP service=PPP priv=1
. . .
Snip
5.3 Troubleshooting Flow Diagrams
Figure 5-3 provides a flowchart for troubleshooting the following three PPP layers:

The physical layer

The Link Control Protocol (LCP) and authentication layer

The Network Control Protocol (NCP) layer