Information
The Source-Address should be set for each External AAA Server configured
Rationale:
RADIUS and TACACS+ are centralized Authentication, Authorization and Accounting (AAA) services.
Both protocols provide services to Authenticate users on routers, switches and other systems. Juniper devices support both RADIUS and TACACS+ Authentication and you should configure at least one External Authentication Server of either type.
For resilience it is generally recommended to configure multiple AAA Servers, which can be of the same type (both TACACS+ or both RADIUS) or can be mixed (one RADIUS and one TACACS+) as required so long as both are configured in [edit system authentication-order].
RADIUS and TACACS+ servers are sensitive systems and should typically be protected by Firewall Filters and ACLs on the RADIUS/TACACS+ Service restricting the Source Address of valid clients. To ensure that these restrictions can be correctly, and strictly, applied - it is important to ensure that the Juniper device always uses the same Source Address when sending packets to these services, irrespective of the route being used.
To do this you should explicitly set the Source Address used for each server (these can be different addresses for different individual servers if required). Typically either the Loopback Address (assigned to Lo0.0) or Out of Band Management address (assigned to FXP0.0) in the Default/Master Virtual Router instance should be used as the Source Address.
Impact:
Ensure that External AAA Servers are tested prior to deploying in a live environment.
It is generally recommended to configure a single 'Rescue' or 'Emergency' account locally under the [edit system login] hierarchy to provide access in the event of a AAA failure or mis-configuration prior to deploying External AAA.
Solution
Configure at least one External Authentication Server using the following commands under the [edit system] hierarchy; For RADIUS
[edit system]
user@host#set radius-server <server ip> secret <shared secret> source-address <loopback IP>
Or for TACACS+
[edit system]
user@host#set tacplus-server <server ip> secret <shared secret> source-address <loopback IP>
Default Value:
No External AAA is used by default