That's odd. I use central authentication for my account, and I'm definitely able to get into my MDS via the API:
[Expert@MyMDS]# mgmt_cli -d "Global" login
Username: zimmie
Password:
uid: "8fb1319e-b00b-4062-84b9-ee705cf053fa"
sid: "8XNsNFG78VUvub477DRkzOiBY7_dB5J9fVCxmBQwetg"
url: "https://127.0.0.1:443/web_api"
session-timeout: 600
api-server-version: "1.8"
user-name: "zimmie"
user-uid: "407b754f-40c6-41c6-bee6-2a113e8c9b94"
[Expert@MyMDS]# vi session.txt # Just to paste the information from above.
[Expert@MyMDS]# mgmt_cli -f json -s session.txt logout
{
"message" : "OK"
}
I'm using RADIUS rather than TACACS (because you can have admins authenticate against a RADIUS group instead of just one TACACS server), but neither RADIUS nor TACACS has any control over permissions.
Does the TACACS server show the user successfully authenticating?