{"uid":"cap_orCljjY__t-I28WfjdVsm","slug":"is-port-21-open-watch-cd69c2b8","name":"is-port-21-open-watch","description":"Change watch for is port 21 open: runs the check, compares it with the result from your previous call for the same host (kept 90 days) and returns the current answer, changed true/false, the fields that changed with before/after values, and when it was last seen. Schedule it to be alerted when this changes. $0.02 per check.","url":"https://ip.intel.rallylive.ca/watch/ip/port/21?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$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"}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.02","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.02/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.02","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_MXw9BvrbSMjLU-y2EZe6_","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.02","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Checks whether port 21 (FTP) is open on a given host, compares with the previous result (kept 90 days), and returns the current status plus a changed flag with before/after field diffs.","exampleAgentPrompt":"Check if port 21 is currently open on 203.0.113.45 and tell me if the status has changed since the last time you checked — I want to know what fields changed and when it was last seen.","exampleUseCases":[{"title":"Alert on unauthorized FTP port opening","prompt":"Keep an eye on port 21 for the IP 198.51.100.10 — let me know immediately if it opens up, since FTP shouldn't be running on that server."},{"title":"Verify FTP service went offline after patching","prompt":"I just disabled FTP on 203.0.113.22 — can you check port 21 and confirm it's now closed compared to the last time you checked?"},{"title":"Scheduled FTP availability monitoring","prompt":"Set up a recurring watch on port 21 for 192.0.2.88 and notify me whenever the open/closed status changes from what was recorded before."}],"resultDescription":"Returns the current open/closed status of port 21, a boolean 'changed' field indicating whether it differs from the previous check, an object listing which fields changed with their before and after values, and a timestamp of when the status was last seen. Results are compared against a stored baseline from up to 90 days ago.","failureModes":["Host unreachable — port scan times out with no result","Invalid or malformed IP address — request rejected","No previous record found — 'changed' field may be null or baseline missing","Payment failure — x402 payment not accepted, check not run","Rate limiting — too many requests in a short window"],"whenToPreferThis":"Choose this endpoint when you need to detect changes to FTP (port 21) availability on a specific host over time, rather than just a one-time check. It is ideal for scheduled monitoring workflows, security alerting pipelines, or compliance checks where you need to know not just the current state but whether it has recently changed. It is preferable over a plain port check when historical comparison and drift detection matter.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-10T18:43:12.739Z","isFirstParty":false,"canonicalSlug":"is-port-21-open-watch-cd69c2b8"}