Lookup for vendor by MAC address. It enough to put the first 3 bytes in the MAC address (6 digits) sinces the MAC address prefix of a vendor is just the first 3 bytes.

MAC Address:

Possible input formats:
00:1C:BF:78:90:AB
00-1C-BF-78-90-AB
00 1C BF 78 90 AB
001CBF7890AB
It's enough to put the first 6 digits, e.g.:
00 1C BF

How to get MAC Address on some operating systems:

Operating System	Action
Windows NT Windows 2000 Windows XP Windows 2003 Windows Vista Windows 2008 Windows 7	Open command prompt: Start->Run->cmd Run: "ipconfig /all" to list all the interfaces The number right to the "Physical Address" is the MAC address for each interface
Linux Solaris/SunOS FreeBSD/NetBSD NeXTStep	Open console as root Run: "/sbin/ifconfig -a" The number right of "HWaddr" is the MAC address