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SiteCheck Web Intel – Open DNS Resolver Check (Port 53)
x402
SiteCheck Web Intel – Open DNS Resolver Check (Port 53) is a paid API for AI agents from api.webintel-api.workers.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-24).
Reports whether Shodan's passive scan data shows TCP port 53 (DNS) open on a given IPv4 address, indicating potential open resolver exposure.
Price / call$0.002
Success—
StatusUnknown
How this service works
Reports whether Shodan's pre-collected passive scan data shows TCP port 53 (DNS) open on an IPv4 address. It is a passive port fact only: it does not send a query, so it cannot say whether the server answers recursively for outside names. Absence means not seen, not closed.
Output
Returns whether Shodan's passive scan records show TCP port 53 open on the specified IPv4 address. The result is a passive observation: a positive result means Shodan previously detected the port open; absence means it was not seen in Shodan's data, not that the port is definitively closed. No active probe is sent.
Example use cases
Checking DNS exposure on a server
“I need to know if the IP 203.0.113.10 has port 53 open according to Shodan's passive scans — I want to see if it might be acting as an exposed DNS server.”
Security audit of cloud infrastructure
“We're auditing our cloud servers. Can you check whether Shodan has seen port 53 open on 192.0.2.55? We want to make sure we're not accidentally exposing a DNS service.”
Investigating a suspicious IP
“There's a suspicious IP 198.51.100.200 in our logs — can you check if Shodan's data shows TCP port 53 open on it to see if it could be used as a DNS resolver?”
Technical details
Endpoint
GEThttps://api.webintel-api.workers.dev/api/security/open-resolver-check?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a fast, passive check on whether a specific IPv4 address has been observed by Shodan with port 53 (DNS) open, without sending any active probe. Ideal for security audits, threat intelligence enrichment, and reconnaissance workflows where you want to avoid active scanning. Prefer this over active DNS probing tools when stealth or passivity is required, or when you want Shodan's historical perspective rather than a real-time network probe.
Side effects
- Missing or invalid IP address returns a 400-level error
- IPv6 addresses are not supported (IPv4 only)
- Shodan may have stale or incomplete data for less-scanned IP ranges
- IP not in Shodan's dataset returns a negative/absent result, which should not be interpreted as definitively closed
- Rate limiting or payment failure may return 402 or 429 errors
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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