Step-1: After receiving the IP address ( 192.168.20.1) from the DHCP server, the station needs to make sure if this IP address is already in use.
Following steps shows how the station discovers duplicate IP address. The station on the network can use the same logic to discover duplicate IP addresses.
WIRESHARK FILTER IP.ADDRESS WINDOWS
We can check the mapping in the ARP cache (table) with “ arp -a” command on both Windows and Linux operating system.
WIRESHARK FILTER IP.ADDRESS MAC
With the reply packet, the station maps the IP address ( 192.168.1.1) to the MAC address ( ca:01:42:f8:00:00). Target IP Address: The station’s IP address is inserted here.Target MAC Address: The station’s MAC address is inserted here.Sender IP Address: The target inserts its own IP address here.Sender MAC: This time the target becomes the sender and adds its MAC address here.Target IP Address: The station (sender) inserts the target IP address here.The sender leaves this field empty and expects the target to fill it. Target MAC Address: The goal of the request is to obtain target MAC address.Sender IP Address: This field contains the station’s (senders) IP address.Sender MAC: This field contains the station’s (senders) MAC address.Step-1: As it is seen in the below screenshot, the station prepares an ARP request packet, which includes following information: The process of mapping an IP address to a MAC address using ARP is below. Before diving deep, we need to thoroughly understand how ARP works. After receiving an IP address from a DHCP server or being assigned an IP address statically, the station starts the procedure of detecting duplicate IP address with an ARP request packet. It simply maps an IP address to a MAC address. What is ARP? And How does the operating system use it to detect duplicate IP address?ĪRP is a network protocol used to find out the hardware (MAC) address of a device from an IP address. It uses Address Resolution Protocol (ARP) to check if there is another client uses the same IP address. So How does Windows operating system detect there is an IP address conflict? The answer is simple. As it is seen, it doesn’t show any information regarding the other station, which uses the duplicate IP address.ĪLSO READ: 9 commands to check if connected to internet with shell script examples Following screenshot is from a Windows operation system detecting an IP address conflict. As I mentioned in this article ( ), the station or the server may check if the IP address is already in use and prevent the conflict. There are chances that the statically configured printer IP address can be assigned to another station. Not all DHCP servers check if an IP address is already in use before assigning it to a station. The idea of assigning a static IP address sounds good but it has a caveat. Otherwise, it would be difficult to use the printer if its IP address was assigned dynamically by the DHCP server in a couple of days. Since it was a network printer, you thought it was a good idea to assign a static IP address to it so that your colleagues can also use it. Imagine you bought a printer and introduced it to the network in the office. However, most of IP conflict happens due to configuration mistakes. Otherwise, an IP conflict arises when two devices on the same network have the same IP address.Īn IP conflict can happen for a variety of reasons. It is very important that an IP address has to be assigned to only one station in the network. Find Duplicate IP Address with WiresharkĪll devices, such as a laptop, desktop, printer, cell phone or tablet connected to a network have its own unique IP address.What is ARP? And How does the operating system use it to detect duplicate IP address?.Ip.addr = 10.0.0.0/24 įrame contains traffic
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