How to check IP conflicts in Linux terminal

Question

Is it there any way to check whether my IP gets conflicted with any other IP at my network?

I'm using Debian system. What are the effective ways or any command to test the network?

Solution

You can send an ARP request or a Neighbour Solicitation for your own address. If you get any replies, then the address is a duplicate.

• For IPv6 this is done automatically. Run ip addr and look at the address flags: addresses currently being checked have a "tentative" flag, and conflicting addresses have "dadfailed".

  Use ndisc6 to do a manual check/query. For example:

  ndisc6 2001:db8:509a:107::1 eth0
  

• IPv4 did not require an automatic duplicate check, but some systems do it anyway. For example, Windows would inform you about duplicates immediately. Many DHCP servers also perform ARP checks before issuing a lease, so if you used DHCP you wouldn't have to worry.

  The corresponding IPv4 tool is arping.

  arping -I eth0 192.168.1.42