Comparing ClearBox TACACS+ vs. RADIUS: Which Authentication Server Fits Your Network?

Secure Access with ClearBox: Advanced TACACS+ and RADIUS Configuration TipsNetwork access control rests on authentication, authorization, and accounting (AAA). ClearBox’s TACACS+ and RADIUS server solutions provide robust, flexible control for device and user access. This article covers advanced configuration techniques, best practices, and troubleshooting tips to harden authentication flows, reduce attack surface, and streamline operations in medium-to-large networks.

Why use ClearBox TACACS+ and RADIUS together?

TACACS+ excels at device command authorization and per-command auditing for network devices (switches, routers, firewalls).
RADIUS is widely used for network access (802.1X, VPNs, wireless) and integrates with NAS (Network Access Servers) and many endpoint clients.

Using both allows you to centralize device/access policies while applying the right protocol for each use case: TACACS+ for network-device management, RADIUS for network-access and tunneled authentications.

Architecture and Deployment Models

1. Single-site, redundant pair

Primary and secondary ClearBox nodes in active/passive or active/active mode.
Synchronized user directory and shared configurations.
Use VIPs or DNS round-robin for client failover.

2. Multi-site with central authentication

Regional ClearBox servers proxy to a central ClearBox or LDAP/AD for user store.
Local authentication caching for resilience during WAN outages.
Geo-aware load balancing or DNS policies.

3. Hybrid cloud/on-prem

On-prem ClearBox for sensitive traffic and cloud ClearBox for distributed remote access.
AD/LDAP federation and secure tunnels (IPsec/DTLS) between locations.

Integration with Identity Stores

Integrate ClearBox with Active Directory (AD) via LDAP or LDAPS for user authentication and group-based authorization.
Use SAML or OAuth identity providers for RADIUS-backed SSO to web applications where ClearBox supports such flows (or via proxying).
For TACACS+, map AD groups to role-based command authorization; use nested group lookups where supported.

Best practices:

Use LDAPS (TLS) to encrypt directory traffic.
Restrict service account permissions to read-only where possible.
Enable group-to-role mappings rather than user-specific policies to simplify scale.

Securing the Protocols

Use strong shared secrets between network devices and ClearBox; rotate periodically and store secrets in a secure vault.
Prefer IPsec or TLS tunnels between ClearBox instances in different sites.
For RADIUS, use RADIUS over TLS (RADSEC) where supported to encrypt authentication payloads (particularly EAP).
For TACACS+, ensure the management plane between devices and ClearBox is protected by an out-of-band management network or ACLs.

Suggested cipher and algorithm guidance:

TLS 1.2+ with ECDHE key exchange, AES-GCM ciphers, and SHA-2 family hashes.
Disable legacy ciphers and protocol versions (TLS 1.0/1.1, MD5-based HMACs).

Advanced Authorization and Policy Design

Role-Based Access Control (RBAC)

Define roles that mirror operational responsibilities (e.g., NetOps-Engineer, Junior-Admin, ReadOnly-Audit).
Map AD/LDAP groups to ClearBox roles to ensure centralized policy enforcement.

Command and Session Command Sets (TACACS+)

Use command authorization to allow specific CLI commands per role.
Implement “permit-then-log” for sensitive commands: require elevated role approval and log executions.
Create safe baselines: deny broad wildcard commands, explicitly allow required subsets.

Attribute-based RADIUS Policies

Use RADIUS attributes to control VLAN assignment, session timeouts, and access limitations for 802.1X and VPN sessions.
Apply dynamic VLANs for guest vs. corporate devices and use downloadable ACLs where supported.

Multi-Factor and Adaptive Authentication

Integrate ClearBox with MFA providers via RADIUS or proxying to add a second factor for both administrative and user access.
For TACACS+ administrative sessions, require an MFA check before privileged role elevation.
Implement adaptive policies: require MFA when connecting from outside trusted networks or during anomalous login patterns.

High Availability and Scaling

Use hierarchical load balancing: local appliance handles immediate authentication; overflow sent to regional pools.
Keep authentication caches for AD/LDAP group memberships on ClearBox to reduce authentication latency and dependency on directory availability.
Monitor key metrics: authentication rate, failed auth spikes, latency, and cache hit ratios.

HA tips:

Ensure clock synchronization (NTP) across ClearBox nodes and clients.
Test failover procedures regularly and validate session handling during node swaps.

Logging, Auditing, and Forensics

Centralize TACACS+ command logs and RADIUS accounting into a SIEM. Include correlated fields: username, source IP, device, command, timestamp, and session ID.
Retain detailed TACACS+ command logs longer than standard auth logs for compliance (PCI, HIPAA).
Use immutable storage or WORM for critical audit records.

Log hygiene:

Mask or redact sensitive parameters (passwords, secrets) before forwarding logs.
Implement alerting on suspicious patterns: repeated failed admin logins, privilege escalations, off-hour device changes.

Troubleshooting Common Issues

Authentication failures:
- Verify shared secrets and time skew.
- Check network ACLs and firewall rules between clients and ClearBox.
- Inspect ClearBox logs for rejected packets and reasons.
Authorization mismatches:
- Confirm AD group-to-role mappings.
- Ensure policy precedence is understood—explicit denies override allows.
Performance issues:
- Monitor CPU/IO on ClearBox appliances; offload heavy logging to separate collectors.
- Tune LDAP query caching and connection pooling.

Include targeted packet captures (RADIUS/TACACS+) when needed to analyze protocol-level failures.

Example Config Patterns

TACACS+ role mapping (conceptual):
- AD group: “Network-Admins” → ClearBox role: “privileged-admin” → allowed command set: full config, reboot, debug.
- AD group: “Network-Auditors” → role: “readonly” → allowed: show/* commands only.
RADIUS dynamic VLAN example (conceptual):
- If AD group == “Guest-Users” then Reply-Message and Tunnel-Private-Group-ID -> VLAN 300.

(Implementation specifics vary by ClearBox version and device vendor; consult ClearBox schema for exact attribute names.)

Maintenance and Change Management

Use staged rollouts: test policies in a lab, then pilot with a small set of devices before wide deployment.
Version and document ClearBox configuration changes in a change control system.
Automate backups of configurations and nightly export of key logs.

Compliance and Privacy Considerations

Ensure logging and retention policies meet regulatory requirements for your industry.
Minimize collection of personally identifying information when unnecessary; store only what’s required for authentication and audit.
Use encrypted transport for auth flows and directory queries to protect credentials.

Closing Checklist

Use LDAPS and secure tunnels; disable legacy ciphers.
Map AD groups to roles; prefer RBAC over per-user rules.
Require MFA for privileged access and adaptive for risky contexts.
Centralize logging to SIEM with long-term retention for audits.
Test HA, failover, and change management regularly.

If you want, I can produce command-level examples for a specific ClearBox version and vendor devices (Cisco IOS/IOS-XE, Junos, Aruba, etc.). Which platform and ClearBox release are you using?