Thursday, September 07, 2017

Duplicate IP Detection in Network

Duplicate IP problem can create trouble time in your network; mostly you will feel it frequenclty dropped connection. It might be caused by wrong DCHP server configuration or more than one network device functioning as DHCP server.

Option 1 :

To detect if it is the case for your problem; you can simply check ARP packets with Wireshark and you will see some packets like the capture below :

Option 2 :

If you dont have Wireshark installed on your device with you. You can use arp-scan command :

$ sudo arp-scan -I eth0 -l | grep -i dup e0:ca:94:d9:ed:80 Askey Computer (DUP: 2) bc:a9:20:e4:85:8e (Unknown) (DUP: 2) 78:31:c1:c4:54:e4 (Unknown) (DUP: 2) 5c:f8:a1:e7:80:5a (Unknown) (DUP: 2) b0:70:2d:a4:9c:97 (Unknown) (DUP: 2) 10:a5:d0:05:9c:85 (Unknown) (DUP: 1) 80:19:34:82:34:a8 (Unknown) (DUP: 2) 40:40:a7:e1:80:02 (Unknown) (DUP: 1) b0:72:bf:7d:e4:f0 (Unknown) (DUP: 2) 64:bc:0c:64:54:87 (Unknown) (DUP: 1) c4:9a:02:5a:2d:db (Unknown) (DUP: 1) c4:9a:02:5a:2d:db (Unknown) (DUP: 2)