Network Security

[Larry Pham]

Hey guys,

Came home today and noticed the lights on my NAS showing activity but none of my computers were on and I wasn't downloading anything. Some investigation revealed someone was accessing my FTP server on my NAS which no one other then me should have access to. I wanted to trace this traffic but couldn't because the NAS is connected to my router and the router's log was not very helpful other then showing the IP and port 21 used by the hacker?

 I need to implement some sort of traffic monitoring and auditing tool/device in between the modem and the router.  

Here's my plan:

I've been wanting to build a small system running Smooth Wall for ages but that requires a bit of time and more resources to setup.  Leveraging my existing computer hardware to avoid having to build a dedicated box just for it, I will create a VM for Smooth Wall. I just need to add a dual gigabit NIC on the computer and dedicate it for Smooth Wall. If my thoughts are correct, I should be able to plug the modem into one NIC and connect the other NIC to the router. If all goes well, I should be able to run my computer with two parallel networks.

Anyone running any kind of proactive security software or hardware on their home network? Just looking for some suggestions or if someone here is doing something similar if would be awesome to hear your experience.
  
Cheers,

Larry