Free tools Windows power users keep installed
One-click scans. No signup required.
The figures are not competing estimates of the same population. They come from different ZoomEye searches: one looked for hosts responding on TCP port 102, another classified devices as PLCs, and a third fingerprinted assets as Siemens S7. Each query applies a different filter, so each answers a different question.
Why do the searches return different totals?
The article’s available search-result excerpt reports 161,907 hosts responding on TCP port 102, 95,749 devices classified as PLCs, and 173 assets fingerprinted as Siemens S7. These are separate query results, not three counts of confirmed Siemens controllers or three estimates of vulnerable devices. ZoomEye search results depend on the filter being applied: a port response, a device category, and a product fingerprint are not interchangeable signals.
As an Amazon Associate I earn from qualifying purchases.
| Reported result | What the query asks | What it establishes |
|---|---|---|
| 161,907 hosts on TCP port 102 | Which hosts answered on that port, according to the reported ZoomEye query. | A port response, not confirmed Siemens identity or vulnerability. |
| 95,749 devices classified as PLCs | Which results ZoomEye classified in the broader PLC category. | A device classification, not specifically a Siemens S7 fingerprint. |
| 173 assets fingerprinted as Siemens S7 | Which results matched the Siemens S7 fingerprint used by the query. | A product-family fingerprint, not proof that the asset is vulnerable or exploitable. |
The available excerpt does not include the exact query strings, scan timestamp, geographic scope, or deduplication method. The counts therefore cannot be independently reproduced from that excerpt, and they should be read as reported search results rather than current totals of unique devices.
What does TCP port 102 tell you?
TCP port 102 is relevant to Siemens S7 because Siemens documentation identifies RFC 1006 over TCP 102 as the route for S7 communication with a controller for programming and diagnostic purposes. That explains why researchers may search the port when investigating industrial control systems; it does not mean every host answering there is a Siemens PLC. See Siemens’ STEP 7 V21 cybersecurity documentation.
#1 Best Overall
- Weight: 1.08lb
- Product Dimensions: 8.00 x 8.00 x 7.00 inches
- Condition: New
Siemens also describes device management over TCP 102 (ISO-TSAP) for specific S7-1200 versions in a ProductCERT advisory. The advisory concerns particular products and vulnerabilities, not every responder on the port. A scan result that shows a service is reachable cannot, by itself, identify the exact device version or establish that an applicable flaw is present. Siemens ProductCERT advisory.
Does an exposed port mean the device is vulnerable?
No. Reachability is a useful security signal, but it is not a vulnerability finding. CISA’s advisory for a specific SIMATIC NET CP343-1 denial-of-service issue discusses TCP port 102 and recommends limiting access to the port to specified IP addresses, for example through a firewall. That is product-specific guidance; it does not show that the 161,907 reported responders include affected devices. CISA advisory on SIMATIC NET CP343-1.
For S7-1200 systems, CISA/ICS-CERT states: “Critical devices should not directly face the Internet.” The practical concern is unnecessary exposure of control-system services, not that every reachable service is exploitable. CISA/ICS-CERT S7-1200 advisory.
How should an organization use counts like these?
Use public scan counts as an indication that services may be discoverable, not as an inventory or incident finding for your own environment. For assets you manage, verify device identity and version through authorized asset records and local inspection, then assess exposure and applicable advisories in context.
Quick Recap
Best Value
- PC adapter USB is the optoelectronic isolated adapter for industrial design. There is anti-surging& anti-lightning protection for the USB and RS485 interface. It support hot plug. Its suitable for S7-300/400/200 series PLC. In particular, it applies to the strong interfere industrial scene and the safeguard in the circuit guarantees the safely running of the system.
- 7972-0CB20-OXAO is optical isolation for industrial design in USB port and RS485 ports are equipped with surge protection and lightning protection circuitry for Siemens S7-300 / 400 and S7-200 series PLC full range PLC. Particularly suitable for interferences fragile industrial field communication port, the circuit in a variety of protective measures to ensure the safe operation of the system.
- Photoelectric isolator: The device is also called a photocoupler, or optocoupler for short. Optical couplers use light as a medium to transmit electrical signals. It has a good isolation effect on input and output electrical signals.The main advantages of optocouplers are: signal transmission in one direction, electrical isolation at the input end and output end, the output signal has no effect on the input end, strong anti-interference ability, and stable operation.
- Features and technical indicators: software version STEP7 V5.2 and above, STEP7 Micro /Win 4.0 and above. MPI baud rate 19.2Kbps, 187.5 Kbps. PPI baud rate 9.6Kbps, 19.2Kbps, 187.5Kbps. The MPI port automatically adapts to the communication rate of 19.2Kbps and 187.5Kbps, 500Kbps, 1.5M Kbps DP master communication.
- Working temperature: -20-+75°C, long-distance communication, communication distance 1000m (RS485 end, when the baud rate is 187.5Kbps)
Rank #4
- Weight: 1.00lb
- Product Dimensions: 7.00 x 7.00 x 7.00 inches
- Condition: New
- Restrict access to industrial control services to trusted networks and explicitly authorized addresses.
- Do not expose critical control-system devices directly to the public internet; use appropriate network segmentation and protective controls.
- Check the specific product and version against the relevant vendor and CISA advisories before drawing conclusions about vulnerability.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
