## POST /api/v2/vps/{id}/firewall

**Add VPS firewall rule**

Add one inbound firewall rule to a VPS. This customer-facing v2 route manages inbound allow/drop/reject rules only, so request `type` must be `in`. Outbound rules or shared firewall-group references may appear in the read response from upstream, but they are not created through this per-VPS write endpoint. Read the firewall list first to check `actions.canAddRule` and rule limits. The create response may have `pos: null`; re-read `GET /api/v2/vps/{id}/firewall` to get authoritative positions before editing or deleting.

### Related Endpoints

- `GET /api/v2/vps/{id}/firewall`: List VPS firewall rules
- `PUT /api/v2/vps/{id}/firewall/{pos}`: Replace VPS firewall rule
- `DELETE /api/v2/vps/{id}/firewall/{pos}`: Delete VPS firewall rule

### Headers

- `Accept`: application/json
- `Authorization`: Bearer YOUR_API_KEY
- Required API scope: `write:vm`
- `Content-Type`: application/json

### Parameters

- `id` (path, string, required): Public VPS ID from `GET /api/v2/vps` `data[].id`. Do not invent this value; use the exact ID returned by the referenced API response. Example: `vps_01hxa3b4c5d6e7f8g9h0j1k2m3`

### Request Body

- `type` (string, required): Inbound rule. Per-VPS v2 firewall writes do not create outbound rules or firewall-group references. Example: `in`
  Allowed values: in
- `action` (string, required) Example: `ACCEPT`
  Allowed values: ACCEPT, DROP, REJECT
- `enabled` (boolean, optional): Omit to keep the platform default for newly staged rules; send true to enable immediately. Example: `true`
- `proto` (string,null, optional) Example: `tcp`
- `dport` (string,null, optional) Example: `22`
- `sport` (string,null, optional) Example: `null`
- `source` (string,null, optional) Example: `198.51.100.10`
- `dest` (string,null, optional) Example: `null`
- `description` (string,null, optional) Example: `Allow SSH from office`

### Request Examples

#### Allow SSH from office

```bash
curl -X POST "https://cloud.hostup.se/api/v2/vps/vps_01hxa3b4c5d6e7f8g9h0j1k2m3/firewall" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Accept: application/json" \
  -H "Content-Type: application/json" \
  -d '{
    "type": "in",
    "action": "ACCEPT",
    "enabled": true,
    "proto": "tcp",
    "dport": "22",
    "source": "198.51.100.10",
    "description": "Allow SSH from office"
  }'
```

```json
{
  "type": "in",
  "action": "ACCEPT",
  "enabled": true,
  "proto": "tcp",
  "dport": "22",
  "source": "198.51.100.10",
  "description": "Allow SSH from office"
}
```

### Response Schema

- `pos` (integer,null, required) Example: `0`
- `type` (string,null, required): Created per-VPS rules are inbound. The list endpoint can still show read-only `out` or `group` rules that already exist upstream. Example: `in`
  Allowed values: in, 
- `action` (string,null, required) Example: `ACCEPT`
  Allowed values: ACCEPT, DROP, REJECT, 
- `enabled` (boolean, required) Example: `true`
- `proto` (string,null, required) Example: `tcp`
- `dport` (string,null, required) Example: `22`
- `sport` (string,null, required) Example: `null`
- `source` (string,null, required) Example: `198.51.100.10`
- `dest` (string,null, required) Example: `null`
- `description` (string,null, required) Example: `Allow SSH from office`
- `isSystem` (boolean, required) Example: `false`
- `editable` (boolean, required) Example: `true`

### Responses

#### 201 - Firewall rule created.
```json
{
  "pos": null,
  "type": "in",
  "action": "ACCEPT",
  "enabled": true,
  "proto": "tcp",
  "dport": "22",
  "sport": null,
  "source": "198.51.100.10",
  "dest": null,
  "description": "Allow SSH from office",
  "isSystem": false,
  "editable": true
}
```

#### 400 - Invalid request. The response body is an RFC 7807 Problem Details document.
```json
{
  "type": "https://developer.hostup.se/errors/invalid_request",
  "title": "Invalid request",
  "status": 400,
  "detail": "The request body failed validation.",
  "code": "invalid_request",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z",
  "errors": [
    {
      "pointer": "/items/0/domainName",
      "detail": "`domainName` is required.",
      "code": "invalid_request"
    }
  ]
}
```

#### 401 - Unauthorized. Authentication is required.
```json
{
  "type": "https://developer.hostup.se/errors/unauthorized",
  "title": "Unauthorized",
  "status": 401,
  "detail": "Authentication is required.",
  "code": "unauthorized",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z"
}
```

#### 403 - Forbidden. The caller lacks a required scope or does not own the resource.
```json
{
  "type": "https://developer.hostup.se/errors/forbidden",
  "title": "Forbidden",
  "status": 403,
  "detail": "The caller lacks a required scope or does not own the resource.",
  "code": "forbidden",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z"
}
```

#### 404 - Not found. The resource does not exist or is not owned by the caller.
```json
{
  "type": "https://developer.hostup.se/errors/not_found",
  "title": "Not found",
  "status": 404,
  "detail": "The requested resource could not be found.",
  "code": "not_found",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z"
}
```

#### 429 - Rate limited. Retry after the limit resets. 429 responses include `Retry-After` seconds plus `X-RateLimit-*` headers.
```json
{
  "type": "https://developer.hostup.se/errors/rate_limit_exceeded",
  "title": "Too many requests",
  "status": 429,
  "detail": "Too many requests. Retry after the limit resets.",
  "code": "rate_limit_exceeded",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z"
}
```

#### 500 - Internal error. Retry later or contact support if the issue persists.
```json
{
  "type": "https://developer.hostup.se/errors/internal_error",
  "title": "Internal server error",
  "status": 500,
  "detail": "An unexpected error occurred. Retry later or contact support if the issue persists.",
  "code": "internal_error",
  "instance": "/api/v2/resource",
  "requestId": "req_01hxa3b4c5d6e7f8g9h0j1k2m3",
  "timestamp": "2026-04-27T12:34:56.000Z"
}
```