Vmware Nsx Security

Use this skill whenever the user needs to manage VMware NSX security — distributed firewall (DFW) policies, security groups, microsegmentation, and IDS/IPS. Directly handles: create/manage DFW policies and rules, security groups, VM tags, network traceflow diagnostics, IDPS profiles and status. Always use this skill for "create firewall rule", "set up microsegmentation", "add VM to security group", "run traceflow", "check IDS status", or any NSX security/DFW task. Do NOT use for NSX networking operations like segments, gateways, NAT, or routing (use vmware-nsx), or VM lifecycle (use vmware-aiops). For load balancing/AVI/AKO use vmware-avi.

Disclaimer: This is a community-maintained open-source project and is not affiliated with, endorsed by, or sponsored by VMware, Inc. or Broadcom Inc. "VMware" and "NSX" are trademarks of Broadcom. Source code is publicly auditable at github.com/zw008/VMware-NSX-Security under the MIT license.

VMware NSX DFW microsegmentation and security — 21 MCP tools for distributed firewall, security groups, VM tags, Traceflow, and IDPS.

Domain-focused security skill for NSX-T / NSX 4.x Policy API. Companion skills: vmware-nsx (networking), vmware-aiops (VM lifecycle), vmware-monitor (read-only monitoring), vmware-avi (AVI/ALB/AKO), vmware-harden (compliance baselines). | vmware-pilot (workflow orchestration) | vmware-policy (audit/policy)

What This Skill Does

Category	Tools	Count
DFW Policy	list, get, create, update, delete, list rules	6
DFW Rules	create, update, delete, get stats	4
Security Groups	list, get, create, delete	4
VM Tags	list VM tags, apply tag, remove tag	3
Traceflow	run trace, get result	2
IDPS	list profiles, get status	2

Total: 21 tools (10 read-only + 11 write)

Quick Install

bash

uv tool install vmware-nsx-security
vmware-nsx-security init      # guided setup: writes config + .env (chmod 600, password grep-safe), then verifies
vmware-nsx-security doctor

When to Use This Skill

• List, create, or modify DFW security policies and rules
• Create security groups based on VM tags, IP ranges, or segment membership
• Apply or list NSX tags on virtual machines
• Run Traceflow to trace a packet path and diagnose drop reasons
• Check IDPS profile configuration, signature status, and global IDS settings
• Implement zero-trust microsegmentation between application tiers

Use companion skills for:

• NSX segments, gateways, NAT, routing, IPAM → vmware-nsx
• VM lifecycle, deployment, guest ops → vmware-aiops
• vSphere inventory, health, alarms, events → vmware-monitor
• Storage: iSCSI, vSAN, datastores → vmware-storage
• Tanzu Kubernetes → vmware-vks
• Load balancing, AVI/ALB, AKO, Ingress → vmware-avi

Related Skills — Skill Routing

User Intent	Recommended Skill
NSX security: DFW rules, security groups, IDS/IPS	vmware-nsx-security ← this skill
NSX networking: segments, gateways, NAT, routing	vmware-nsx
Read-only vSphere monitoring, alarms, events	vmware-monitor
VM lifecycle, deployment, guest ops	vmware-aiops
Storage: iSCSI, vSAN, datastores	vmware-storage
Tanzu Kubernetes	vmware-vks
Multi-step workflows with approval	vmware-pilot
Compliance baselines (CIS / 等保 / PCI-DSS), drift detection, LLM remediation advisor	vmware-harden (uv tool install vmware-harden)
Load balancer, AVI, ALB, AKO, Ingress	vmware-avi (uv tool install vmware-avi)
Audit log query	vmware-policy (vmware-audit CLI)

Common Workflows

Implement App-Tier Microsegmentation

Pre-flight (judgment — DFW changes can lock everyone out):

• Default-allow first: the very first rule in any new policy must be ALLOW for management traffic (DNS, NTP, vCenter, SSH from jumphost). Without it, the moment you add a default-deny you blackhole your own access.
• Tag inventory: confirm the VMs you intend to protect actually carry the tag (tag list <vm>). A group based on a non-existent tag matches zero VMs — the policy will appear "applied" but enforce nothing.
• Category choice: Application for app-tier microseg (rules evaluated late, after Infrastructure rules pass through). Using Emergency for routine rules will starve real incident-response capacity.
• Stateless? Default to stateful — NSX DFW is stateful and almost no rule should be stateless. Stateless = both directions must be explicitly allowed.
• Always start with logging enabled on new rules; disable later once verified. Silent drops are the worst kind of bug.

Steps:

1. Tag the VMs first (see workflow below) — empty groups = no enforcement
2. Create groups via the create_group MCP tool with tag_scope/tag_value (the tag condition is matched as "scope|tag", e.g. tier|web; note multiple criteria types — tag/IP/segment — are ORed, not ANDed)
3. policy create app-microseg --category Application
4. Add rules in order: ALLOW management → ALLOW intra-tier → ALLOW web→app on app-port → DROP any-any with logging
5. Verify with traceflow (see below) before enabling default-deny

Apply NSX Tags to VMs

Judgment: tags drive group membership which drives DFW enforcement. A misspelled tag silently excludes a VM from protection. Always re-list after applying.

1. tag list my-web-vm-01 → record the VM external ID, also see what tags already exist (avoid duplicates / typo collisions)
2. tag apply <vm-external-id> --scope tier --value web
3. Verify: tag list my-web-vm-01 again → confirm the new tag is present AND no unexpected ones

Trace a Packet with Traceflow

Judgment: traceflow is your verification mechanism for any DFW change. Run it before enabling deny rules and after every rule modification. Don't trust "looks right in the UI."

1. Get source VM's logical port ID via vmware-nsx troubleshoot vm-segment
2. traceflow run <lport-id> --src-ip <src> --dst-ip <dst> --proto TCP --dst-port <port>
3. Inspect the DFW hit chain: which rule matched, ALLOW or DROP, and at which transport node
4. Common failure: rule matches at category Application but is shadowed by an earlier DROP at category Environment — read the trace top-to-bottom, not just the final verdict

Check DFW Policy Hit Counts

bash

vmware-nsx-security policy list
vmware-nsx-security rule list <policy-id>
vmware-nsx-security rule stats <policy-id> <rule-id>

Multi-Target Operations

All commands accept --target <name> to operate against a specific NSX Manager:

bash

# Default target
vmware-nsx-security policy list

# Specific target
vmware-nsx-security policy list --target nsx-prod
vmware-nsx-security group list --target nsx-lab

Usage Mode

Scenario	Recommended	Why
Local/small models (Ollama, Qwen)	CLI	~2K tokens vs ~8K for MCP
Cloud models (Claude, GPT-4o)	Either	MCP gives structured JSON I/O
Automated pipelines	MCP	Type-safe parameters, structured output

MCP Tools (21 — 10 read, 11 write)

All MCP tools accept an optional target parameter.

Category	Tool	Type	Description
DFW Policy	list_dfw_policies	Read	List all DFW security policies with category, sequence, and rule count
	get_dfw_policy	Read	Get policy details: category, stateful, locked, scope, tags
	create_dfw_policy	Write	Create a new DFW policy with category and sequence number
	update_dfw_policy	Write	Partial update: display_name, description, sequence_number, stateful
	delete_dfw_policy	Write	Delete policy — refuses if active rules exist
	list_dfw_rules	Read	List rules in a policy: action, sources, destinations, services
DFW Rules	create_dfw_rule	Write	Create rule with sources/destinations/services/action/scope
	update_dfw_rule	Write	Partial update rule fields
	delete_dfw_rule	Write	Delete a rule from a policy
	get_dfw_rule_stats	Read	Get packet/byte/session/hit counts and popularity_index for a rule
Security Groups	list_groups	Read	List all security groups with expression count
	get_group	Read	Get group details: expression criteria + up to 50 effective VM members
	create_group	Write	Create group with tag/IP/segment membership criteria (tag matched as "scope|tag"; multiple criteria ORed)
	delete_group	Write	Delete group — refuses if referenced by DFW rules/scopes, or if the reference scan fails
VM Tags	list_vm_tags	Read	List NSX tags on a VM by display name
	apply_vm_tag	Write	Apply a scope/value tag to a VM (additive, preserves existing tags)
	remove_vm_tag	Write	Remove a scope/value tag from a VM (other tags preserved; may change dynamic group membership)
Traceflow	run_traceflow	Write	Inject probe packet; returns operation_state + hop-by-hop observations (by resource_type) + dfw_hits
	get_traceflow_result	Read	Check operation_state/observations of an existing traceflow
IDPS	list_idps_profiles	Read	List IDPS profiles with severity and filter criteria
	get_idps_status	Read	Get IDPS signature status + global IDS settings (auto_update, syslog export)

CLI Quick Reference

bash

# DFW Policy
vmware-nsx-security policy list [--target <name>]
vmware-nsx-security policy get <policy-id>
vmware-nsx-security policy create <id> --name "Display Name" --category Application [--dry-run]
vmware-nsx-security policy delete <id> [--dry-run]

# DFW Rules
vmware-nsx-security rule list <policy-id>
vmware-nsx-security rule stats <policy-id> <rule-id>
vmware-nsx-security rule delete <policy-id> <rule-id> [--dry-run]

# Security Groups
vmware-nsx-security group list
vmware-nsx-security group get <group-id>
vmware-nsx-security group delete <group-id> [--dry-run]

# Tags
vmware-nsx-security tag list <vm-display-name>
vmware-nsx-security tag apply <vm-external-id> --scope env --value production [--dry-run]
vmware-nsx-security tag remove <vm-external-id> --scope env --value production [--dry-run]

# Traceflow
vmware-nsx-security traceflow run <lport-id> --src-ip &lt;src-ip&gt; --dst-ip &lt;dst-ip&gt;

# IDPS
vmware-nsx-security idps profiles
vmware-nsx-security idps status

# Diagnostics
vmware-nsx-security doctor [--skip-auth]

Troubleshooting

"Cannot delete policy — active rules exist"

delete_dfw_policy checks for active rules before deleting. Use vmware-nsx-security rule list <policy-id> to see which rules need to be removed first. Then delete each rule individually before retrying the policy deletion.

"Cannot delete group — referenced by DFW rules"

delete_group scans all policies for references to the group in rule source_groups, destination_groups, and applied-to scope, plus policy-level scope. Remove the group from those references first (via update_dfw_rule replacing the group path with 'ANY' or another group), then retry. If the error says the reference scan itself failed, deletion was aborted as a precaution — verify NSX connectivity with vmware-nsx-security doctor and retry.

"No virtual machine found with display_name"

list_vm_tags looks up VMs by display name via the NSX fabric API. Common causes:

1. Display name mismatch — the name in NSX Manager may differ from vCenter. Check vmware-monitor vm list for the exact NSX fabric display name.
2. VM not registered — newly deployed VMs may take a minute to appear in the NSX fabric.
3. Multiple VMs with the same name — use apply_vm_tag with the specific external_id.

Traceflow returns empty observations

1. If operation_state is IN_PROGRESS, the trace has not finished — poll again with get_traceflow_result <traceflow-id>.
2. Verify the src_lport_id is the correct logical port attachment UUID — not the segment port path. Get it from vmware-nsx troubleshoot vm-segment <vm>.
3. The source VM must be powered on and connected to an NSX overlay segment.
4. If the VM is on a VLAN-backed segment, Traceflow is not supported.
5. NSX Manager requires the transport node hosting the source VM to be reachable. Check vmware-nsx health transport-nodes.

DFW rule stats show zero hits

A newly created rule will have zero hit counts until traffic matches it. If expected traffic still shows zero:

1. Confirm the rule is not disabled (disabled: false in list_dfw_rules output).
2. Check that source/destination group membership is correct using get_group.
3. Verify rule sequence number — a lower-sequence rule with ALLOW/DROP may be matching first.

"Password not found" error

Password variable convention: VMWARE_NSX_SECURITY_<TARGET_UPPER>_PASSWORD where hyphens are replaced by underscores. For target nsx-prod: VMWARE_NSX_SECURITY_NSX_PROD_PASSWORD. Check ~/.vmware-nsx-security/.env.

invalid peer certificate: UnknownIssuer (uvx)

Corporate TLS proxy not trusted by uv's bundled cert store. Use the v1.5.15+ single-command form vmware-nsx-security mcp (no PyPI re-resolve), or export UV_NATIVE_TLS=true to make uv use the system cert store.

Safety

• Audit logging: All write operations logged to ~/.vmware/audit.db (SQLite WAL, via vmware-policy) with timestamp, user, target, operation, parameters, and result
• Dependency checks: delete_dfw_policy checks for active rules; delete_group checks for DFW rule references — prevents accidental cascade failures
• Input validation: All IDs validated against safe character set (alphanumerics, hyphens, underscores, dots); all text fields sanitized to strip control characters
• Dry-run mode: CLI write commands support --dry-run to preview API calls without executing
• Double confirmation: CLI destructive operations (delete) require two separate confirmation prompts
• Credential safety: Passwords loaded only from environment variables (.env file), never from config.yaml
• No networking changes: Cannot modify segments, gateways, NAT, or routing — that scope belongs to vmware-nsx
• Prompt injection defense: All API-sourced strings passed through _sanitize() before inclusion in tool output

Setup

bash

uv tool install vmware-nsx-security
mkdir -p ~/.vmware-nsx-security
cp config.example.yaml ~/.vmware-nsx-security/config.yaml
# Edit config.yaml with your NSX Manager targets

# Add to ~/.vmware-nsx-security/.env (create if missing, chmod 600):
# VMWARE_NSX_SECURITY_NSX_PROD_PASSWORD=<your-password>
chmod 600 ~/.vmware-nsx-security/.env

vmware-nsx-security doctor

All tools are automatically audited via vmware-policy. Audit logs: vmware-audit log --last 20

Full setup guide: see references/setup-guide.md

Architecture

text

User (natural language)
  |
AI Agent (Claude Code / Goose / Cursor)
  | reads SKILL.md
vmware-nsx-security CLI or MCP server (stdio transport)
  | NSX Policy API (REST/JSON over HTTPS)
NSX Manager
  |
DFW Policies / Rules / Security Groups / Tags / IDPS

The MCP server uses stdio transport (local only, no network listener). All connections to NSX Manager use HTTPS on port 443.

Audit & Safety

All operations are automatically audited via vmware-policy (@vmware_tool decorator):

• Every tool call logged to ~/.vmware/audit.db (SQLite, framework-agnostic)
• Policy rules enforced via ~/.vmware/rules.yaml (deny rules, maintenance windows, risk levels)
• Risk classification: each tool tagged as low/medium/high/critical
• View recent operations: vmware-audit log --last 20
• View denied operations: vmware-audit log --status denied

vmware-policy is automatically installed as a dependency — no manual setup needed.

License

MIT — github.com/zw008/VMware-NSX-Security