---
title: "Open port scan check — Lemwatch Help"
description: "Weekly scan of the top 20 attack-surface ports (SSH, RDP, MySQL, Redis, MongoDB…) so a forgotten firewall rule cannot silently expose your DB."
canonical: "https://lemwatch.com/help/open-port-scan-check"
source: "https://lemwatch.com"
---

# Open port scan check

> Weekly scan of the top 20 attack-surface ports (SSH, RDP, MySQL, Redis, MongoDB…) so a forgotten firewall rule cannot silently expose your DB.

## Quick answer

 Lemwatch runs a lightweight TCP SYN probe against 20 high-risk ports weekly. New unexpected opens raise **severity: high**.

## What it checks

- SSH (22), RDP (3389), Telnet (23)

- MySQL (3306), Postgres (5432), Redis (6379), MongoDB (27017), Memcached (11211), Elasticsearch (9200)

- FTP (21), SMB (445)

- Common admin panels (8080, 8443, 10000)

## Where to find it in Lemwatch

 **Site details → Security → Ports.**

## How to respond

- Confirm whether the port is intentionally open.

- If not, close it at the cloud firewall or security group.

- If required (SSH), restrict source IPs and enable key-only auth.

- Acknowledge to baseline the new state.

## FAQ

### Is this an intrusive scan?

 No — single SYN packet per port, no exploit attempts, throttled to be invisible to standard IDSes.

### Do you scan all 65k ports?

 No — only curated high-risk ports. A full scan would trigger AUP violations on most clouds.

## Related

- Bypassing bot protection

- Lemwatch IP whitelisting

- Fixing 5xx errors from firewall


## Related

- [Help centre](https://lemwatch.com/help)
- [Bypassing bot protection for Lemwatch checks](https://lemwatch.com/help/bypassing-bot-protection)
- [Whitelist Lemwatch monitoring IPs](https://lemwatch.com/help/lemwatch-ip-whitelisting)
- [Fixing 5xx errors caused by your firewall](https://lemwatch.com/help/fixing-5xx-errors-from-firewall)
- [HSTS header check](https://lemwatch.com/help/hsts-header-check)
- [Content-Security-Policy header check](https://lemwatch.com/help/csp-header-check)
- [Lemwatch pricing](https://lemwatch.com/pricing)
- [PagerDuty Integration](https://lemwatch.com/help/pagerduty-integration)