searching through 2 text files

I have 2 text files One has arp list IP Address MAC Address Type ---------------- ------------------ ---------- 165.166.182.204 00:0a:04:98:b5:d3 dynamic One file has a mac list Modem MAC Address IP Address CPE IP Address CPE MAC Address CPE Source ----------------- --------------- ---------------- - ---------------- ----------- 00:00:39:46:88:57 10.21.2.236 165.166.182.204 00:0a:04:98:b5:d3 Learned Just an example - there are about 5000 entries in each file (more in the mac list) What I am trying to do is match the mac address from the arp file to a cpe Mac address in the Mac file and return modem Mac and ip address from Mac list. I can open the arp and set what I want to an array. But matching up is where I hit a wall.. Thanks for any help or at least a point in some direction Alan