How To Find IP Conflicts In Linux

This tool sends ARP (Address Resolution Protocol) packets on local network to collect the addresses. If there is multiple MAC addresses claiming the same IP address, then there is conflict.

To install arp-scan on Ubuntu or Debian type:

To install arp-scan on Ubuntu or Debian type:

$ sudo apt-get install arp-scan

For Fedora, CentOS or Redhat:

$ sudo yum install arp-scan

To detect IP conflicts, run the following:

$ sudo arp-scan –I eth0 -l

An output example:

192.168.1.10   00:1b:a9:63:a2:4c       BROTHER INDUSTRIES, LTD.
192.168.1.30   00:1e:8f:58:ec:49       CANON INC.
192.168.1.33   00:25:4b:1b:10:20       Apple, Inc
192.168.1.37   10:9a:dd:55:d7:95       Apple Inc
192.168.1.38   20:c9:d0:27:8d:56       (Unknown)
192.168.1.39   d4:85:64:4d:35:be       Hewlett Packard
192.168.1.39   00:0b:46:e4:8e:6d       Cisco (DUP: 2)
192.168.1.40   90:2b:34:18:59:c0       (Unknown)

In this instance, the 19.168.1.39 IP is in conflict since it appears twice.