Open Ports & Services Discovery
Every host on the internet exposes a set of TCP ports. Each open port reveals a service — SSH for remote administration, HTTP(S) for web servers, FTP for file transfer, DNS for name resolution, RDP for remote desktop, Modbus for industrial control systems, MQTT for IoT messaging. QROS scans every open port and identifies the service behind it.
How QROS discovers open ports
QROS connects to every indexed host and attempts a TCP handshake on each of 51 common ports — from the well-known (22, 80, 443) to the industrial (502 Modbus, 20000 DNP3) and IoT (1883 MQTT, 8883 MQTTS, 9100 printer). For each open port, QROS:
- Grabs the banner the service presents to any connecting client
- Parses the banner to identify the software (OpenSSH, nginx, Apache, vsftpd, Redis, MongoDB, Elasticsearch)
- Detects the version and matches it against the NVD CVE catalog
- Reads the TLS certificate on encrypted ports (443, 8443, 993, 995, 636, 465)
- Identifies web technologies when a web page is served (WordPress, Magento, Next.js, React, Vue, Drupal)
What you see in a QROS host dossier
When you open a host in QROS Explore, you see a complete dossier with every open port, the service behind it, the software version, and any CVEs. Here's an example of what a host dossier looks like:
scanme.nmap.org · United States · Fremont · Linode
| Port | Service | Software | CVEs |
|---|---|---|---|
| 22 | SSH | OpenSSH 6.6.1 | 5 |
| 80 | HTTP | Apache 2.4.7 | 11 |
Why open port discovery matters
You can't secure what you can't see. Most organisations don't know which ports their servers expose to the internet. An open Redis on port 6379 without authentication, an RDP on 3389 exposed to the world, or a Modbus on 502 with no firewall — these are the entry points attackers use. QROS gives you the same visibility attackers already have, so you can close unnecessary ports before they're exploited.
Search open ports by country, service or product
QROS Explore lets you search the entire indexed host database by port, service, product, country or CVE — no login required. Search all hosts with SSH, all HTTPS endpoints, all RDP servers, or all Modbus devices in seconds.
The 51 ports QROS scans
FAQ
How does QROS scan open ports?
QROS connects to every indexed host on 51 common TCP ports and attempts a TCP handshake. For each open port, it grabs the service banner, identifies the software and version, and reads the TLS certificate on encrypted ports.
What ports does QROS scan?
QROS scans 51 common ports including SSH (22), HTTP/HTTPS (80, 443, 8080, 8443), FTP (21), DNS (53), RDP (3389), Modbus (502), MQTT (1883, 8883), Redis (6379), MongoDB (27017), Elasticsearch (9200), and more.
Is port scanning legal?
Yes. QROS only reads what a host exposes to any connecting client — open ports, banners and certificates. It does not bypass security measures, authenticate, exploit, or access personal data. See the legal notice for the full analysis under Spanish and European law.
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