I am currently using Ubuntu 15.04 and I have installed arp-scan with apt-get. If I run it I get a list of machines with their IP addresses, MAC addresses and about half of them say the make, others say (Unknown). Recently I booted Linux Kali on the same machine from a USB and Kali comes with arp-scan preinstalled. When I ran arp-scan in Kali I got the same list of IP addresses, MAC addresses and all makes. My question is why and how does Kali gets all the names of makes for machines on my network while Ubuntu seems to have troubles with it?