Cisco NX-OS Security Hardening

Cisco NX-OSAdvanced

Security hardening for Cisco Nexus: AAA, SSH hardening, role-based access, CoPP, disable unnecessary services, and management plane protection.

↓ example.txt

What is it?

NX-OS security hardening follows many of the same principles as IOS hardening, but leverages NX-OS's role-based access control (RBAC) and feature-based architecture. NX-OS has built-in roles (network-admin, network-operator, vdc-admin) that control what commands each user can run. The feature model is an advantage: services not enabled with 'feature' simply don't exist on the switch. NX-OS also has 'Control Plane Policing (CoPP)' pre-configured by default — protecting the switch CPU from traffic flooding attacks.

✓ When to use

·Before deploying any Nexus switch to production
·After a security audit or compliance review
·For PCI-DSS, SOC 2, or HIPAA compliance in data center environments
·When establishing a security baseline for a new data center deployment

✗ When NOT to use

·In a lab environment where rapid config changes are needed — strict exec timeouts slow troubleshooting. Use separate lab and production configs.
·Disabling 'feature dhcp' when Nexus is acting as a DHCP relay — verify first with 'show run | inc dhcp'

How it compares

vs Cisco IOS hardeningNX-OS has RBAC (roles) built in — you assign users to roles, not privilege levels. NX-OS 'feature' model means services don't exist if not enabled (more secure by default). IOS has more granular CoPP configuration.

vs CIS Benchmark for NX-OSCIS publishes specific benchmarks for NX-OS. This template covers the most impactful controls. The full CIS benchmark includes additional checks like image signing verification, VDC security, and AAA timeout settings.

Prerequisites

→TACACS+ server configured and reachable from mgmt0 before applying AAA config
→Management ACL must include your actual management source IPs — wrong IPs cause lockout
→Verify which features are in use before disabling them: 'show feature' to see enabled features
→Test console access before restricting VTY lines — console is not affected by VTY ACLs

Config Generator

Hostname *

Admin Password *

TACACS+ Server IP

TACACS+ Key

Management ACL Name

Allowed Management Sources

Disable Telnet?

Disable CDP?

Disable HTTP server?

Verification commands

show ip ssh

Verify SSH is enabled on the switch

Expected: SSH Enabled - version 2.0

show aaa authentication

Show AAA authentication configuration and status

Expected: Lists authentication methods for login and console. TACACS+ should be primary with local as fallback.

show role

Show available RBAC roles and their permissions

Expected: Lists built-in roles (network-admin, network-operator) and any custom roles

show users

Show currently logged-in users and their source

Expected: Lists username, access method (ssh), source IP, and assigned role

Debug commands

show aaa accounting log last 20

Show recent AAA accounting events (commands entered)

Common mistakes & fixes

⚡ Locked out after applying management ACL

Cause: Management ACL has wrong source network or does not include your management IP

Fix: Use console access (not restricted by VTY ACL). Modify the ACL to include your management subnet.

⚡ TACACS+ authentication failing

Cause: TACACS+ server unreachable from mgmt VRF, or wrong shared key

Fix: Test: 'test aaa group tacacs+ <user> <pass>'. Verify server is reachable: 'ping <tacacs-ip> vrf management'. Local fallback should keep you in if TACACS+ fails.

⚡ User cannot run certain commands after role assignment

Cause: User assigned to 'network-operator' role which is read-only by default

Fix: Create a custom role with specific command permissions, or change user to 'network-admin' role for full access.