I have developed a product which provides two ethernet ports. The internal module which manages the eth is a switch with its own mac address that can be modified. To every product I am assigning a mac taken from our company database. Aiming to test both the eth ports I designed the following test:

it is just sufficient to connect one port to the network and the other port to a known device. If I am able to ping that device it means both ports are working. Ip addresses are given by dhcp.

Actually I am looking at the arp table in order to find the address of the device to be pinged. For other purposes I need to know the ip address of the product containing the 2 eth and to which I assigned the mac address. Again it would be simple to just look at the arp table, but, when the mac address has been set, the arp shall be updated.

I specify I must use windows. For now I used nmap -v -sn --unprivileged but seems it is not working on our production site.

What could be another trick/method that can be used to find the product ip or for updating the arp table?

Thanks in advance

  • You say nothing about Your device software. Is TCP stack and DHCP client installed there? Your "trick" with nmap work for your device in lab environment but not in production? Your test of transit traffic wok in production environment?
    – mmv-ru
    Commented Jun 29, 2016 at 11:39
  • 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 could provide and accept your own answer.
    – Ron Maupin
    Commented Aug 14, 2017 at 18:38

1 Answer 1


ARP is a protocol (that's redundant, Address Resolution Protocol is, of course, a protocol) and the result of the protocol is to populate an ARP table in the devices. So, the answer to your question of "How to update arp table" is to use the ARP protocol. Any device that needs to speak IP on an Ethernet needs to participate in ARP.

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