netbox-windows-dhcp 1.3.2

NetBox plugin for full integration with Windows DHCP Server via PowerShell Universal

netbox-windows-dhcp

A NetBox v4.5.0+ plugin for full integration with Windows DHCP Server via PowerShell Universal (PSU v5).

Features

• Define Windows DHCP Servers (hostname, port, HTTP/HTTPS, App Token auth, optional SSL verification)
• Define DHCP Failover relationships (Load Balance or Hot Standby)
• Correlate DHCP Scopes with NetBox Prefixes (many scopes → one prefix)
• Lease lifetime stored in seconds, displayed in the most readable unit (e.g. 3 Days, 73 Hours, 30 Minutes)
• Global library of reusable DHCP Option Values with Option Code Definitions (pre-populated with all standard Windows DHCP built-in codes)
• One-time Import from Server — pulls failovers, scopes, scope-level option values, and exclusion ranges from a live DHCP server into NetBox
• Active sync mode: pull leases and reservations → create/update NetBox IP Addresses with status, DNS name, and client MAC
• Stale record cleanup: expired leases and removed reservations are deleted or downgraded automatically
• Push reservations, scope config, and exclusion ranges from NetBox → DHCP server (optional, settings-controlled)
• DHCP Scopes panel injected into the NetBox Prefix detail view
• All sync and import operations run as background jobs — no HTTP timeouts on large servers
• All background job changes appear in the NetBox changelog (attributed to the user who queued the job)
• Scheduled background sync (hourly by default, configurable) + manual Sync Now per server or for all servers
• Maintenance mode on servers, failover relationships, and scopes — pauses sync without changing configuration
• Server health checks — live connectivity status, PSU reachability, and script version visible in the UI
• Automatic secondary fallback — when a failover primary is unreachable or in maintenance mode, failover-scope syncing routes through the secondary automatically
• Update PSU Scripts — push the latest endpoint scriptBlocks to PSU directly from NetBox without manually touching the server
• Full REST API for all plugin objects (with optional enable/disable toggle)
• Plugin-wide settings managed via the NetBox UI (no PLUGINS_CONFIG entry required)

Requirements

NetBox host

• NetBox >= 4.5.0
• Python >= 3.10
• requests >= 2.28
• NetBox RQ workers running (required for background sync and import jobs)

Each Windows DHCP server

• Windows Server 2016 or later with the DHCP Server role installed
• PowerShell Universal v5.x (tested on 5.6.11+) — see PSU Setup
• DhcpServer PowerShell module (included with the DHCP Server role)

Installation

1. Install the package

pip install netbox-windows-dhcp

Or from source (editable install recommended for development):

pip install -e /path/to/netbox-windows-dhcp

2. Add to NetBox configuration (configuration.py)

PLUGINS = [
    'netbox_windows_dhcp',
]

No PLUGINS_CONFIG entry is required. All settings are managed through the plugin's Admin → Settings page in the NetBox UI.

3. Run migrations

python manage.py migrate

Running migrations also triggers the post_migrate signal which auto-registers the dhcp_client_id custom field on IP Address objects.

4. Restart NetBox

Restart gunicorn/uwsgi and the RQ workers.

Getting Started

Set up PSU on each DHCP server

Before adding a server to NetBox, PSU must be installed and configured on the Windows DHCP server. See psu/README.md for the complete deployment guide, including:

• Firewall and HTTPS configuration
• Creating the DHCPReader and DHCPWriter PSU roles with setup_roles.ps1
• Deploying the API endpoints from NetBox with the Update PSU Scripts button

Add a DHCP Server

1. Go to Windows DHCP → Infrastructure → Servers → Add
2. Enter the hostname/IP, port, and PSU App Token (from setup_roles.ps1 output)
3. Toggle Use HTTPS as appropriate (default: on)
4. If the server uses a self-signed certificate, leave Verify SSL Certificate enabled and click Fetch Certificate on the edit page to import it inline — no need to navigate away
5. Click Save, then Update PSU Scripts on the server detail page to push the endpoint definitions to PSU

Note: The App Token field displays blank when editing an existing record — this is intentional. Leaving the field blank preserves the stored value. Enter a new value only when you need to rotate the credential.

CA Certificate

If the PSU server uses a self-signed TLS certificate, import it inline on the server edit page:

1. Click Fetch Certificate in the CA Certificate section of the edit form.
2. The plugin retrieves the certificate and displays its Subject, SANs, Issuer, expiry date, and SHA-256 fingerprint.
3. Verify the fingerprint against the actual server certificate, then click Trust This Certificate. The cert is staged in the form and saved to the database when you click Save.

Once stored, the certificate is used automatically whenever Verify SSL Certificate is enabled. The server detail page shows the CN and expiry inline in the DHCP Server attributes table, with Replace and Remove buttons. A warning badge appears when the cert is within 90 days of expiry or has expired.

Warning: Always verify the SHA-256 fingerprint before trusting a certificate. Trusting an unverified certificate can expose your DHCP API traffic to interception.

Import from a Server

Once a server is configured, click Import from Server on the server detail page to run a one-time background import of:

• Failover relationships (matched to existing DHCP Server objects by hostname)
• Scopes (NetBox Prefixes are created automatically if they don't exist, when Create Missing Prefixes on Import is enabled — see Settings)
• Scope-level option values (unknown option codes are created automatically)
  • Option 3 (Router) and Option 51 (Lease Time) are skipped — they are stored directly on the Scope object

You will be redirected to the job status page where you can monitor progress and view the full results log. Existing records are skipped; the import never overwrites data already in NetBox.

Configure Sync Settings

Go to Windows DHCP → Admin → Settings to configure:

Setting	Description
DHCP Lease Status	IP Address status assigned to active DHCP leases by the sync. Defaults to dhcp. Changing this mid-deployment causes the next sync to update all managed lease IPs to the new status.
DHCP Reservation Status	IP Address status assigned to DHCP reservations by the sync, and the status that triggers a push to the DHCP server when Push Reservations is enabled. Defaults to reserved.
Sync IP Addresses from Leases & Reservations	When checked, pull leases and reservations and create/update/delete NetBox IP Address records. When unchecked, sync scope config only.
Push Reservations to DHCP Server	Push NetBox IPs with the configured reservation status to the DHCP server as reservations
Push Scope Info to DHCP Server	Push scope config changes from NetBox to the DHCP server
Sync Active Scopes Only	When checked, only scopes with State: Active on the DHCP server are pulled during sync. Inactive/disabled scopes are ignored. Useful during server migrations when the replacement server has scopes in an inactive state that should not yet be managed by NetBox.
Create Missing Prefixes on Import	When checked (default), importing a scope whose CIDR does not exist in NetBox automatically creates the Prefix. Uncheck if Prefixes are managed by another source.
Sync Interval (minutes)	How often the background sync runs (5–1440)
Sync Job Queue	Worker queue priority (High / Default / Low) used for all sync and import background jobs. Default: Default.
Sync-Protected Tag	A NetBox tag. Any IP Address carrying this tag, or whose IP falls within a Prefix carrying this tag, is fully shielded from sync — its status, DNS name, and record itself are never modified or removed. Leave blank to disable.
Update Client ID for Protected IPs	When enabled, the sync updates the dhcp_client_id custom field on protected IPs to match the DHCP server's active lease. All other sync writes remain blocked. Useful after a server replacement when the client MAC changes.
API Enabled	When unchecked, all plugin REST API endpoints return 503 Service Unavailable. Use this to disable external API access without removing credentials or changing permissions.

The DHCP Lease Status and DHCP Reservation Status settings allow the plugin to work with custom IP Address statuses defined in NetBox's FIELD_CHOICES configuration. The status validation, sync logic, cleanup rules, and push behavior all apply to whichever statuses are configured here.

Editing Rules

Not all objects in the plugin support full CRUD. The table below summarises what operations are allowed and under what conditions.

Failover Relationships

Operation	Allowed
View	✅ Always
Delete	✅ Always
Create	❌ Never — import from the DHCP server
Edit	✅ Via direct URL only (not exposed in the UI)

Failover relationships are created automatically during an Import from Server run. The Add button and Edit button are intentionally hidden from the list and detail views — relationships should be managed on the DHCP server and imported into NetBox. The Sync Enabled toggle on the list view is the primary way to manage a failover relationship after import.

DHCP Scopes

Operation	Push Scope Info off	Push Scope Info on
View	✅	✅
Create	❌	✅
Edit	❌	✅
Delete	❌	✅

When Push Scope Info to DHCP Server is disabled, the DHCP server is the source of truth for scope configuration. Scopes reach NetBox via Import from Server and are kept up to date by periodic sync. Direct edits are blocked to prevent NetBox from drifting out of sync with the server.

When Push Scope Info to DHCP Server is enabled, NetBox becomes the source of truth. Scope changes saved in NetBox are pushed to the DHCP server on the next sync. Full CRUD is permitted.

Note: Exclusion Ranges follow scope info — create, edit, and delete are permitted whenever Push Scope Info is enabled, and blocked when it is disabled.

IP Address Status Validation

Any IP Address with status dhcp must satisfy both of the following conditions when saved through the UI or REST API:

1. The IP address must fall within the prefix of at least one configured DHCP Scope.
2. The IP address must not fall within any exclusion range of that scope.

This validation runs during form submission and API writes. It does not run during background sync — the sync sets statuses based on authoritative data from the DHCP server and bypasses this check by design.

The reserved status is not validated against DHCP scope membership — it is a general-purpose NetBox status used for both DHCP reservations and non-DHCP purposes.

There are no UI-level restrictions on editing IP addresses with dhcp or reserved status beyond the above. Changes made manually to DHCP-managed IPs will be overwritten on the next sync if Sync IP Addresses from Leases & Reservations is enabled.

[!IMPORTANT] Throughout this documentation, dhcp and reserved are used as placeholder names for the statuses assigned to DHCP leases and reservations respectively. The actual statuses used by the plugin are configurable in Windows DHCP → Admin → Settings via the DHCP Lease Status and DHCP Reservation Status fields. The validation logic, sync behavior, and cleanup rules described here all apply to whichever statuses are configured, not specifically to the built-in dhcp and reserved values.

Scope Source

Every DHCP Scope must be associated with exactly one of:

• Server — for standalone scopes that are not part of a failover relationship. Set automatically during Import from Server when the scope has no failover name.
• Failover Relationship — for scopes managed under a Windows DHCP failover pair.

This association determines which server is responsible for syncing the scope. Standalone scopes are only synced against their assigned server; failover scopes are synced via the primary server of their failover relationship.

Sync Behavior

Scope eligibility

Not every scope is synced on every server. Before processing a scope, the sync checks eligibility:

Scope type	Synced when
Standalone (has Server)	Server's Sync Standalone Scopes is enabled, and the scope's assigned server matches the server being synced
Failover-linked	The failover relationship's Sync Enabled is on, and the server being synced is the primary of that failover
Neither assigned	Never synced

Server pre-flight: If a server has Sync Standalone Scopes disabled and is not the primary server for any active failover relationship, the sync skips it entirely — no network connection is made.

Server health checks

At the start of every sync job run, the plugin checks the health of each server before performing any sync work:

1. GET /api/dhcp/health is called for each server (if not in maintenance mode).
2. A successful response marks the server Healthy and records the PSU script version in the database.
3. If the request fails, the server is marked Unreachable and the error is recorded.
4. Health status, last check time, and PSU script version are visible in the server list and detail view.

Health check results from the single-server Sync Now action cover only the target server. If that server is unreachable, the job fails immediately with no fallback attempted.

Secondary failback

When a failover primary is unreachable (health check failed) or in maintenance mode, and the secondary server is healthy and not in maintenance mode, the plugin automatically routes failover-scope sync through the secondary for that job run:

• Failover-linked scopes are synced against the secondary instead of the primary.
• The secondary's own standalone scopes are not affected — they sync independently based on the secondary's own Sync Standalone Scopes setting.
• This is entirely automatic — no configuration change is needed.

Note: Secondary fallback applies only to failover-linked scopes. If a primary server is down, its standalone scopes are inaccessible via the secondary in Windows DHCP and are skipped.

Server pre-flight: If a server has Sync Standalone Scopes disabled and is not the primary server for any active failover relationship, the sync skips it entirely — no network connection is made.

Per-failover sync control

Each failover relationship has a Sync Enabled toggle (visible on the failover list and toggleable per-row). When disabled, all scopes using that failover are excluded from sync. This allows pausing sync for a specific failover pair without affecting others.

IP Address sync

When Sync IP Addresses from Leases & Reservations is unchecked (default), the sync pulls and stores scope config only — no IP Address objects are created or modified.

When checked, the sync pulls leases and reservations from each DHCP server and creates/updates/deletes NetBox IP Address records.

IP Address lifecycle (active sync)

Creating and updating:

Source	IPAddress.status	dns_name	dhcp_client_id
Active DHCP lease	dhcp	Hostname from DHCP (lowercased)	Client MAC address
DHCP reservation	reserved	Name from reservation (lowercased)	Client MAC address

Reservations take precedence — a reserved IP is not overwritten by a lease record for the same address.

Special case — reserved IP with no dhcp_client_id: If a reserved IP address has no dhcp_client_id set (e.g. it was manually created before the client MAC was known), and a lease is discovered on the DHCP server for that address, the sync will populate dhcp_client_id from the lease but will not change the status or dns_name. This allows the IP to be pre-registered before provisioning.

New IP Addresses are created using the prefix length of the associated scope's NetBox Prefix (not /32).

The dhcp_client_id custom field (auto-registered on IP Address) stores the client MAC address in Windows DHCP hyphen-separated format (00-11-22-33-44-55).

All IP Address creates and updates are recorded in the NetBox changelog, attributed to the DHCP-Sync-Service account (auto-created on first migrate). This makes sync-driven changes clearly distinguishable from human edits in the audit trail. DHCP lease metadata (lease hostname, active status, expiration) is stored in a separate non-changelog side-table (DHCPLeaseInfo) and displayed on the IP Address detail page — these updates do not generate changelog entries.

Cleanup (stale record removal):

After syncing leases and reservations for a scope, the plugin removes records that no longer exist on the server:

NetBox status	dhcp_client_id	DHCP-managed?	Server state	Action
dhcp	—	—	Lease still active	No change
dhcp	—	—	Lease expired or gone	Deleted
reserved	—	—	Any	Never auto-deleted (pre-staged or manual)
reserved	set	No (manually created)	Any	Never auto-deleted
reserved	set	Yes (sync-created)	Reservation still exists	No change
reserved	set	Yes (sync-created)	No reservation, but lease exists	Downgraded to dhcp
reserved	set	Yes (sync-created)	Neither reservation nor lease	Deleted

"DHCP-managed" means the record was created or previously updated by the sync (indicated by a DHCPLeaseInfo side-record). Manually-created reserved IPs are never auto-deleted even if they have a dhcp_client_id.

Note: When Push Reservations to DHCP Server is enabled, NetBox is the source of truth for reservations. reserved IP Addresses with a dhcp_client_id are never deleted or downgraded based on server state — they will be pushed to the server on the next sync instead.

Scope cleanup:

When a scope exists in NetBox but is no longer reported by the DHCP server, and the server was successfully reached, and Push Scope Info to DHCP Server is disabled, the scope is deleted from NetBox. Only scopes whose Scope Source links them to the server being synced (either directly as a standalone scope, or via a failover relationship where this server is primary) are considered.

When Push Scope Info to DHCP Server is enabled, a scope missing from the server will instead be created on the server.

Safety: If the API call to fetch leases/reservations fails for a scope, cleanup is skipped for that scope. If list_scopes() fails entirely, the server is unreachable and no cleanup runs at all.

Pre-Staging IPs

To register a device in NetBox before its client MAC is known, create the IP Address with:

• Status reserved
• dns_name set to the planned canonical hostname
• Leave dhcp_client_id blank

The sync will never delete or overwrite the status or dns_name of a reserved IP with no dhcp_client_id. If a lease appears on the DHCP server for that address, the sync populates dhcp_client_id from the lease (so the reservation can be pushed once the MAC is known) but leaves everything else unchanged.

Typical lifecycle:

1. Create the IP in NetBox with status reserved, dns_name set to the planned hostname, and no dhcp_client_id.
2. Device is provisioned; it receives a DHCP lease. The sync populates dhcp_client_id from the lease.
3. Once dhcp_client_id is set, the reservation is pushed to the DHCP server on the next sync (if Push Reservations is enabled). The dns_name is used as the reservation name on the server.

Sync Now

The Sync Now button on a server detail page enqueues a background sync job and redirects to the job status page. The full sync log is visible there.

Sync Now is blocked when maintenance mode is enabled on a server — disable maintenance mode first. Sync continues normally for other servers.

Maintenance Mode

Maintenance mode is available on all three object types: Servers, Failover Relationships, and Scopes. When enabled, the object is skipped entirely during sync:

• Server in maintenance — The entire server (all scopes) is skipped. Sync Now is also blocked on that server.
• Failover relationship in maintenance — All scopes linked to that failover are skipped, regardless of server health.
• Scope in maintenance — That individual scope is skipped; other scopes on the same server continue normally.

Maintenance mode stores when it was enabled and by which user. A Notes field is available for free-form context (e.g. a ticket number or reason). All three fields are cleared automatically when maintenance mode is disabled.

Toggling maintenance mode

• Single-item: Click the amber pause icon on the list row, or open the object detail page and use the action button. A confirmation form shows the current state with an option to enable or disable and add optional notes.
• Bulk: Select objects on the list page and click Bulk Maintenance Mode. Choose enable or disable and optionally set notes (applied to all selected objects).

Current Maintenance view

Windows DHCP → Admin → Current Maintenance shows a combined table of every object currently in maintenance mode across all three types — sorted by enabled time, filterable by type. Use this as a dashboard to see what is paused before triggering a sync. Each row has a Resume button to disable maintenance inline; select multiple rows and click Resume Selected to bulk-disable across object types in one action.

Sync-Protected IPs

Any IP Address tagged with the configured Sync-Protected Tag is fully shielded from sync writes. The sync will never change its status, DNS name, or dhcp_client_id, and will never delete the record during cleanup.

Prefix-level protection: The tag can also be applied to a NetBox Prefix (any prefix, not just the scope's prefix). Every IP address that falls within a tagged prefix is protected, even if the IP itself does not carry the tag. This provides deep inheritance — a tag on a /16 protects all IPs within it, including those in nested /24 sub-prefixes that don't themselves carry the tag.

Combined rule: an IP is protected if it carries the tag or falls within any prefix that carries the tag.

DHCP lease metadata (DHCPLeaseInfo) is always updated for protected IPs regardless of protection status — the lease hostname, active state, and expiration are still recorded and visible on the IP Address detail page.

Update Client ID for Protected IPs

Enable this checkbox to allow one narrow exception: the sync may update the dhcp_client_id custom field on a protected IP when the server's active lease carries a different client MAC. All other writes (status, DNS name, record deletion) remain blocked. This is useful after a DHCP server replacement where the client MAC for the same device changes.

Typical use: Tag an IP as protected when it has been manually configured and should not be overwritten by automated sync, even if the DHCP server has a conflicting record.

Lease Lifetime Display

Lease lifetimes are stored in seconds and displayed in the most readable exact unit:

• 86400 → 1 Day
• 259200 → 3 Days
• 262800 → 73 Hours (not an exact number of days)
• 3600 → 1 Hour
• 60 → 1 Minute
• 45 → 45 Seconds

When configuring a scope, enter the value and select the unit (Seconds / Minutes / Hours / Days). The form defaults to 1 Day for new scopes. Values learned from the DHCP server are automatically decomposed to the largest clean unit.

Navigation

The plugin adds a Windows DHCP menu to the NetBox left sidebar:

• Infrastructure → Servers, Failover
• Scopes → Scopes
• Options → Option Values, Option Code Definitions
• Admin → Current Maintenance, Settings

PSU Setup

See psu/README.md for the full PSU deployment guide (fresh install, upgrades, manual setup).

The plugin expects PowerShell Universal v5.x (tested on 5.6.11+) on each DHCP server, exposing endpoints under /api/dhcp/. The endpoint script is bundled with the plugin and deployed to PSU via the Update PSU Scripts button — no manual file copying required.

Endpoint reference

Method	Path	Description
GET	/api/dhcp/scopes[?active_only=true]	List all scopes (includes router and failover name); pass active_only=true to exclude inactive/disabled scopes
GET	/api/dhcp/scopes/:scope_id	Get a single scope
POST	/api/dhcp/scopes	Create a scope
PUT	/api/dhcp/scopes/:scope_id	Update a scope
GET	/api/dhcp/leases[?scope_id=]	List active leases
GET	/api/dhcp/reservations[?scope_id=]	List reservations
POST	/api/dhcp/reservations	Create a reservation
PUT	/api/dhcp/reservations/:client_id	Update a reservation
DELETE	/api/dhcp/reservations/:client_id	Delete a reservation
GET	/api/dhcp/failover	List failover relationships
POST	/api/dhcp/failover	Create a failover relationship
GET	/api/dhcp/options/server	Server-level option values
GET	/api/dhcp/options/scope/:scope_id	Scope-level option values
GET	/api/dhcp/exclusions?scope_id=	List exclusion ranges for a scope
POST	/api/dhcp/exclusions	Create an exclusion range
DELETE	/api/dhcp/exclusions	Delete an exclusion range (body: scope_id, start_ip, end_ip)
GET	/api/dhcp/health	Health check (read) — returns {"status":"ok","version":"x.y.z"}
POST	/api/dhcp/health	Health check (write) — tests write access; returns {"status":"ok"}

Authentication: PSU v5 App Tokens are sent as Authorization: Bearer <token>. Generate a token in the PSU admin console under Security → App Tokens and paste it into the App Token field on the DHCP Server object in NetBox.

PSU script version tracking

The PSU script embeds a version constant ($PSUScriptVersion). The plugin defines a matching PSU_SCRIPT_VERSION Python constant and checks it during the health check phase of every sync:

• When the versions match, a green check mark and version number appear in the server list.
• When they mismatch, an amber warning icon and the observed version appear. The sync continues normally — the mismatch is advisory only, logged in the job output.
• When the version is unknown (no health check has run yet), a gray question mark appears.

The health check also confirms read/write access on every sync run; results update the server's Health Status (Healthy / Unreachable / Unknown) and Last Health Check time visible in the server list and detail view.

Updating PSU scripts from NetBox

When a new plugin version includes updated endpoint scriptBlocks, push them directly from NetBox without touching the server:

1. Open the DHCP Server detail page and click Update PSU Scripts.
2. The job fetches the current endpoint records from PSU, updates each one's scriptBlock in place, creates any new endpoints, removes any deleted endpoints, then restarts PSU's endpoint definitions.
3. A follow-up health check verifies the new version is live and updates psu_script_version in the database.

The App Token used for sync must have apis/* permission on the PSU DHCPWriter role (configured automatically by setup_roles.ps1). Bulk update is available from the server list page.

PLUGINS_CONFIG Overrides

For environments where a production database is replicated to a dev or staging NetBox instance, PLUGINS_CONFIG in configuration.py can override credentials and sync behavior without touching the database.

Per-server API key

PLUGINS_CONFIG = {
    'netbox_windows_dhcp': {
        'server_overrides': {
            'dhcp01.example.com': {'api_key': 'dev-token-here'},
            'dhcp02.example.com': {'api_key': 'dev-token-here'},
        }
    }
}

The match key is the server's Hostname field (exact string match). When an override is active, the server detail page shows a notice and the value stored in the database is not used.

The value is a dict to allow additional per-server overrides to be added in future versions without a breaking configuration change.

Global sync behavior

Three boolean settings can be forced off (or on) regardless of what is saved in the Plugin Settings UI:

PLUGINS_CONFIG = {
    'netbox_windows_dhcp': {
        'sync_ips_from_dhcp': False,   # disable IP sync in dev
        'push_reservations': False,    # prevent pushing reservations to prod DHCP servers
        'push_scope_info': False,      # prevent pushing scope changes to prod DHCP servers
    }
}

Use None (or simply omit the key) to leave the database value in effect. True or False forces the setting regardless of what is saved in the UI.

When any of these overrides are active, the Plugin Settings page shows a banner listing the overridden fields and their current values. The affected checkboxes are disabled to prevent confusion.

Note: Overriding push_scope_info to False also blocks scope create, edit, and delete in the UI, since those operations are gated on this setting.

REST API

The plugin exposes a REST API under /api/plugins/netbox-windows-dhcp/:

Endpoint	Model
/servers/	DHCP Servers
/failover/	Failover relationships
/option-codes/	Option Code Definitions
/option-values/	Option Values
/scopes/	DHCP Scopes (includes nested exclusion_ranges)
/exclusion-ranges/	DHCP Exclusion Ranges