My company has 2 separated networking systems: wired and wireless. The R&D department is now developing an application that runs on a PC to scan the devices on the wireless network (smartphones and tablets) with a specific port open. The thing is the PCs can connect to both networks at the same time. So if the application scans the port using built-in functions of Windows/Linux (2 main OS of my company's PCs) will it affect the networks' stability since I have heard that it will scan for ports on all connected networks and there can be more than 1 PC to run this app at the same time.

  • 6
    Ask them what they intend to do when they get IPv6 with 18,446,744,073,709,551,616 possible addresses per subnet. I hope they can wait 584,942,417 years at 1000 addresses scanned per second.
    – Ron Maupin
    Sep 15 '15 at 3:23
  • What, so the 'port scanning' will check all the IP address for the port? Is there any way to restrict the IP range to scan?
    – jcp0908
    Sep 15 '15 at 9:38
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    @jcp0908 that's not a question for us, that's a question for your R&D department writing the application.
    – Nanban Jim
    Sep 18 '15 at 19:33
  • It would affect performance to some degree certainly. However how much would depend on how frequent and wide scaled the scans will be. As for stability, there would be no way to answer. Some devices don't like to be scanned (or scanned in certain ways); network printers in my experience tend to be most affected by network scans of some types (may lock up, print garbage, etc). One really won't know how devices will react to a scan until you do it. If you are looking for devices with a specific port open (i.e. running a certain service), can't it just advertise itself to the PC?
    – YLearn
    Oct 28 '15 at 2:43
  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer.
    – Ron Maupin
    Jan 5 '21 at 18:38

A full subnet scan of all ports will impact your network performance, especially on a wireless network as those are basically a hub network.

You can minimize the amount of noise by limiting your port scans to 1 IP and 1 port at a time (as clients connect, take their IP and specifically scan them for only the ports you are looking for).

  • Thanks for the tip. I've already given the heads up for the R&D dep, and they will test thoroughly before launching.
    – jcp0908
    Sep 28 '15 at 9:12

If they restrict scanning to the IP range of the wireless network (highly recommended, you shouldn't have too many issues on your LAN, even if the source of the scan is connected to it.

Each scan would be at worst a TCP connection initiated to each IP in a range - bandwidth-wise this would be trivial.


We ran into this at my company during a Red Team visit. The technician performing the nmap did not specify a range or restrict the scan in anyway and it hammered our DMZs. CPU on the firewall maxed out a 99%, restricted his port manually to fix the issue and then had him scan the inside interfaces, followed by each DMZ individually.

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