Palo Alto Management Access through TACACS

Prior to 8.0,  TACACS was limited to Authentication only. If you wanted to authenticate against a TACACS server to log in to the GUI or CLI, you had to create the same admin accounts on the Palo Alto Networks device. This doesn't scale well and its additional overhead, especially in large or dynamic environments. Hence, with the launch of PAN-OS 8.0, TACACS has been enchanced to use the Authorization from the TACACS server.

You no longer need to create admins locally, just the admin roles.

Follow the below steps to achieve this.

1. Create  a TACACS server profile and an Authentication profile.

2. Create admin roles as per your requirement.

Custom role with limited accessSample permissions for this custom role

3. TACACS server side-configuration is next. I used Cisco ACS in this example.

Two example users created an ACS.This attribute gives admin level privileges, as per the custom admin defined on PA, to a successfully authenticating admin user.This gives ‘superuser’ privileges to the user. However, you can replace the value to be any of the pre-defined values (or even a custom value, as illustrated above).Tailor the rules to match the users with their respective shell profiles

4. If everything is configured correctly, you should see successful logins.Superuser has access to everythingNotice the limited access for this custom userSystem logs showing logins for both admins

Troubleshooting

• The Palo Alto Networks firewall, by default, uses the management interface to communicate with the TACACS server. However, you can change this to any interface under Service route configuration ('Device' tab).

• You can also check the connectivity, authentication and the attributes passed, via the test command:

admin@anuragFW> test authentication authentication-profile TACauth username TACsuperuser password
Enter password :

Target vsys is not specified, user "TACsuperuser" is assumed to be configured with a shared auth profile.

Do allow list check before sending out authentication request...
name "TACsuperuser" is in group "all"

Authentication to TACACS+ server at '10.21.56.103' for user 'TACsuperuser'
Server port: 49, timeout: 3, flag: 0
Egress: 10.21.56.125
Attempting PAP authentication ...
PAP authentication request is created
PAP authentication request is sent
Authorization request is created
Authorization request sent with priv_lvl=1 user=TACsuperuser service=PaloAlto protocol=firewall
Authorization succeeded
Number of VSA returned: 1
 VSA[0]: PaloAlto-Admin-Role=superuser
Authentication succeeded!

Authentication succeeded for user "TACsuperuser"

•  Sometimes the issue is on the server side, so check the logs on the TACACS server too.
• If you need to decrypt the TACACS packets to view the content, you can decrypt it on Wireshark.

Enter the shared secret in the box

•  It's always a good idea to check the authd.log file (ideally in debug mode) when you are troubleshooting authentication related issues.