# is-port-502-open

> is-port-502-open is a paid API for AI agents from ip.intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-12).

Checks whether TCP port 502 (Modbus) is open, closed, or filtered on a given host by attempting a connection from Cloudflare's edge network.

## Facts

- Endpoint: GET https://ip.intel.rallylive.ca/ip/port/502?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/is-port-502-open-2159534d
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_txPlQGjkx59SyVNhuegbf

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability is-port-502-open-2159534d
```

Example prompt: Can you check if TCP port 502 (Modbus) is open or exposed on the host 192.168.1.100 — I want to know if it's reachable from the internet without running a local scanner.

## When to prefer this

Use this endpoint when you need a quick, passive check of whether Modbus (TCP port 502) is exposed on a host without running a local port scanner or installing any tooling. Ideal for security audits, compliance checks, or pre-deployment verification of OT/ICS devices. Prefer this over general-purpose port scanners when you want a lightweight, pay-per-check approach from Cloudflare's edge perspective with no setup overhead.

## Known failure modes

- Host is Cloudflare-fronted — result returned as 'inconclusive' because Cloudflare's edge answers the connection attempt
- Host or IP unreachable — may return filtered or timeout
- Invalid hostname or IP format in query — likely 4xx error
- Connection attempt blocked by intermediate firewall — reported as filtered rather than closed
- Service temporary unavailability — upstream probe error

## How this service works

Is TCP port 502 (Modbus) open on a host? Attempts a connection from Cloudflare's edge and reports open/closed/filtered with the connect time; Cloudflare-fronted hosts are reported as inconclusive because their edge answers for them. Exposure checks for Modbus without running a scanner. $0.01 per check.

## Output

Returns whether TCP port 502 is open, closed, or filtered on the target host, along with the connection time in milliseconds. If the host is Cloudflare-fronted, the result is marked as inconclusive because Cloudflare's edge intercepts the connection on behalf of the origin.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/is-port-502-open-2159534d/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from ip.intel.rallylive.ca](https://www.zero.xyz/host/ip.intel.rallylive.ca/llms.txt)