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.
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.
vmware-policy auto-installed as Python dependency (provides @vmware_tool decorator and audit logging). All write operations audited to ~/.vmware/audit.db. Credentials: Each NSX Manager target requires a per-target password env var in ~/.vmware-nsx-security/.env following the pattern VMWARE_NSX_SECURITY_<TARGET_NAME_UPPER>_PASSWORD. Passwords are never logged or echoed. Destructive operations: DFW policy delete checks for active rules, security group delete checks for references. IDS/IPS config changes require double confirmation. Traceflow is read-only. No webhooks, no outbound network calls, no guest operations. Local only: stdio MCP + NSX Policy API (HTTPS 443). Transitive dependencies: Only vmware-policy (audit/policy). No post-install scripts or background services.
VMware NSX Security
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.
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:
Tag the VMs first (see workflow below) — empty groups = no enforcement
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)
policy create app-microseg --category Application
Add rules in order: ALLOW management → ALLOW intra-tier → ALLOW web→app on app-port → DROP any-any with logging
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.
tag list my-web-vm-01 → record the VM external ID, also see what tags already exist (avoid duplicates / typo collisions)
tag apply <vm-external-id> --scope tier --value web
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."
Get source VM's logical port ID via vmware-nsx troubleshoot vm-segment
Inspect the DFW hit chain: which rule matched, ALLOW or DROP, and at which transport node
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
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:
# 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
All MCP tools accept an optional target parameter.
list_dfw_policies, list_dfw_rules, list_groups and list_idps_profiles return the family
list envelope — {items, returned, limit, total, truncated, hint} — rather than a bare array.
Read the rows from items and check truncated before concluding a listing is complete; a
50-row default page looks identical to a whole estate without it. total is stated only where
the scan proved it: it is the real count on an unfiltered listing that stayed under the
1000-item get_all cap, and null for name-filtered listings, capped scans, and
list_dfw_rules (whose fetch is bounded to the requested window). A null total with
truncated: true means "there may be more" — page with offset to confirm. Errors return
{error, hint} (a dict, not a one-element list).
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
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
# 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 <src-ip> --dst-ip <dst-ip>
# 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 named ... exists in the NSX fabric inventory"
list_vm_tags looks up VMs by display name via the NSX fabric API. Common causes:
Display name mismatch — the name in NSX Manager may differ from vCenter. Check vmware-monitor vm list for the exact NSX fabric display name.
VM not registered — newly deployed VMs may take a minute to appear in the NSX fabric.
Multiple VMs with the same name — use apply_vm_tag with the specific external_id.
Traceflow returns empty observations
If operation_state is IN_PROGRESS, the trace has not finished — poll again with get_traceflow_result <traceflow-id>.
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>.
The source VM must be powered on and connected to an NSX overlay segment.
If the VM is on a VLAN-backed segment, Traceflow is not supported.
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:
Confirm the rule is not disabled (disabled: false in list_dfw_rules output).
Check that source/destination group membership is correct using get_group.
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
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
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)
