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1721
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13
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23
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1720 not using ACS to authenticate

richardcalvert
Level 1
Level 1

my AAA commands;

aaa new-model

aaa authentication login default group tacacs enable

aaa authorization exec default group tacacs none

aaa accounting connection default start-stop group tacacs

aaa session-id common

tacacs-server host [server address]

tacacs-server key [key]

ip tacacs source-interface fast 0

and the debug for authentication and tacacs;

00:08:50: AAA/AUTHEN/LOGIN (00000007): Pick method list 'default'

00:08:50: TPLUS: Queuing AAA Authentication request 7 for processing

00:08:50: TPLUS: processing authentication start request id 7

00:08:50: TPLUS: Authentication start packet created for 7()

00:08:50: TPLUS: Using server 201.0.99.97

Password:

00:08:55: TPLUS(00000007): Select Timed out

00:08:55: AAA/AUTHEN/ENABLE(00000007): Processing request action LOGIN

00:08:55: AAA/AUTHEN/ENABLE(00000007): Done status GET_PASSWORD

Nacogdoches>

00:08:59: AAA/AUTHEN/ENABLE(00000007): Processing request action LOGIN

00:08:59: AAA/AUTHEN/ENABLE(00000007): Done status PASS

I can ping the tacacs server from the router. This set of commands does work for the 1841's that I'm using.

23 Replies 23

Jagdeep Gambhir
Level 10
Level 10

Do you see any hits on acs passed or failed attempts? Make sure you are using correct source interface.

There are no hits in failed attempts, I can see my passed logins from the other routers. I currently have the source interface set to loopback 0, and have also tried setting the source to fast0 with the same result. The weird part is that these commands work flawlessly on all my 1841's. This is ACS 4.1 on server 03 if that helps.

ACS -->network configuration ---> Router --->IP

The IP address defined in acs should be of the interface defined as "tacacs source" in router.

Did you check the shared secret key?

Please get

debug aaa authentication

debug aaa authorization

01:33:46: AAA/AUTHEN/LOGIN (00000008): Pick method list 'default'

Password:

01:33:51: AAA/AUTHEN/ENABLE(00000008):

The IP of the source interface is the same one specified in ACS, and I also verified the shared secret is correct.

Processing request action LOGIN

01:33:51: AAA/AUTHEN/ENABLE(00000008): Done status GET_PASSWORD

Nacogdoches>

01:33:54: AAA/AUTHEN/ENABLE(00000008): Processing request action LOGIN

01:33:54: AAA/AUTHEN/ENABLE(00000008): Done status PASS

Are you able to clear the first user name password prompt?

or it is not accepting enable password? what error you get after issuing enable password?

the first prompt is using the enable password as failover for ACS, so I can get past the login, and the prompt for the EN password, its just not hitting the ACS box with the request. Here is login/EN without the debug.

Press RETURN to get started.

Password:

Nacogdoches>en

Password:

Nacogdoches#

Check if any firewall is blocking tacacs port. Try to telnet on port 49 using acs ip address

There are no firewalls other than at the pc level from my desk to the ACS box. I'm starting to think there's something unique with the 1720.

Richard

I have had quite a few 1720s that authenticate with ACS without problem. I do not think your issue is something unique about the 1720.

Can you do debug tacacs authentication, try another login, and post the debug output?

HTH

Rick

HTH

Rick

This is me trying to login via telnet, with debug on for Tacacs, and authentication/authorization. I'm not sure why its timing out, I can ping the ACS server, however ping fails when I specify the source, Loopback 0, which is my tacacs source.

02:10:57: AAA/AUTHEN/LOGIN (0000000A): Pick method list 'default'

02:10:57: TPLUS: Queuing AAA Authentication request 10 for processing

02:10:57: TPLUS: processing authentication start request id 10

02:10:57: TPLUS: Authentication start packet created for 10()

02:10:57: TPLUS: Using server 201.0.99.97

02:11:02: TPLUS(0000000A): Select Timed out

02:11:02: AAA/AUTHEN/ENABLE(0000000A): Processing request action LOGIN

02:11:02: AAA/AUTHEN/ENABLE(0000000A): Done status GET_PASSWORD

02:11:04: AAA/AUTHEN/ENABLE(0000000A): Processing request action LOGIN

02:11:04: AAA/AUTHEN/ENABLE(0000000A): Done status PASS

02:11:04: AAA/AUTHOR (0xA): Pick method list 'default'

02:11:04: TPLUS: Queuing AAA Authorization request 10 for processing

02:11:04: TPLUS: processing authorization request id 10

02:11:04: TPLUS: Sending AV service=shell

02:11:04: TPLUS: Sending AV cmd*

02:11:04: TPLUS: Authorization request created for 10()

02:11:04: TPLUS: Using server 201.0.99.97

02:11:09: TPLUS(0000000A): Select Timed out

02:11:09: AAA/AUTHOR/EXEC(0000000A): Authorization FAILED

Richard

It is helpful to know that a standard ping to the TACACS server does work but that an extended ping which specifies the source as the loopback fails. This suggest that there is a routing problem and that the TACACS server does not have a route to the subnet of the loopback.

Would you be able to start from the TACACS server and do a traceroute toward the loopback address. It might be interesting to see how far that gets and it might help to identify where the problem is.

HTH

Rick

HTH

Rick

The problem I'll have with a trace route is that the IP I'm using for Loopback 0 is a real IP outside my network. When I run TR its just going to hop to the real world IP. I can use TR from the ACS server to the outside NAT IP on the router, but thats only one hop.

C:\tracert 207.16.131.110

Tracing route to 207.16.131.110 over a maximum of 30 hops

1 1 ms 1 ms 1 ms 207.16.131.110

Would it be possible for you to post the relevant part of one of your configs so that I can compare it with mine?

Richard

Can you tell us about the network translation, is it static translation or dynamic, or is it using overload to PAT on the outbound interface? I wonder if the issue with TACACS has anything to do with the translation?

Relevant information from one of the 1721s that do successfully authenticate with TACACS:

IOS (tm) C1700 Software (C1700-ADVSECURITYK9-M), Version 12.3(22), RELEASE SOFTWARE (fc2)

aaa authentication login default group tacacs+ line

aaa authentication enable default group tacacs+ enable

aaa authorization exec default group tacacs+ if-authenticated

interface Loopback0

ip address 10.42.186.2 255.255.255.255

ip tacacs source-interface Loopback0

tacacs-server host 172.16.24.20

tacacs-server host 172.16.130.103

tacacs-server key [removed]

and an extended ping from the router to the TACACS server using the loopback as source does get successful responses.

HTH

Rick

HTH

Rick

We use static translation. As for PAT I dont believe we are using it, I made any port settings in the router or in the ACS server. I do have this command in the router;

ip nat inside source route-map nonat interface FastEthernet0 overload

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