“Allowing network engineers to log into core switches using shared local admin passwords is a massive security compliance failure. TACACS+ AAA centralizes authentication and logs every command.”

While managing Artemis Hospital’s network infrastructure for HCL Infosystems in 2008, 50 Cisco Catalyst L2/L3 switches were initially managed using shared local passwords.

Architecture: Centralized TACACS+ AAA & WPA2-Enterprise Wireless

We implemented Cisco Secure ACS 4.0 to centralize authentication, authorization, and accounting (AAA) for all network equipment and hospital wireless users.

1. TACACS+ Switch Administration: Every SSH/Telnet CLI command was authorized in real-time by Cisco ACS and logged with the engineer’s domain user ID.
2. Secure Medical Wireless (Aironet APs): Configured 802.1X WPA2-Enterprise EAP-TLS authentication for mobile doctor workstations, completely isolating Guest Wi-Fi onto a separate VLAN via Cisco ASA 5510 subinterfaces.

[!IMPORTANT] Always configure local fallback admin accounts on switches for emergency access if the centralized TACACS+ server becomes unreachable during link outages.

# # Cisco Switch AAA TACACS+ Configuration for Cisco ACS 4.0
tacacs-server host 192.168.10.5 key SecretTacacsKey123
aaa new-model
aaa authentication login default group tacacs+ local
aaa authorization exec default group tacacs+ local
aaa accounting commands 15 default start-stop group tacacs+

The Verdict

Key Takeaway

Enforce Individual TACACS+ Command Accounting on All Core Network Appliances.

Never use shared passwords. Deploying Cisco ACS / TACACS+ provides explicit command-level audit trails required for healthcare and financial compliance.