The questions wasn't "newbie" of you. I'd say it was a good one.

If you run a router that's a boxed off the shelf product it's not going to be a simple matter of watching traffic. Ron has that info already so I'll go into a different situation where this is a little easier to do:

You have X number of machines running Windows on a network, and a BSD or Linux box that you use FOR the router; This set up is a little easier. You take a really old machine you use as a door stopper or something, like a 386 or 486, pop Slackware or BSD on that, add a bunch of network cards, a few of the things that the installer for both OSs listed asks if you'd like them, and then you use that machine as your router, and you can log into it over SSH, or Telnet if you're feeling frisky, and start up one of these apps, and watch the traffic.

One of the things that some people probably appreciate about these OSs is they don't require a brand new processor to run. You can still use a 386 machine to run a basic non GUI OS to test things on.

And considering how slow the stuff is it's probably much cooler running than most processors you'll find now anyway.

During the Slackware installation, towards the end where it asks what services you want set up, it has the option to run the machine as a router to do this. Slackware needs a 486 though, but really, how much difference is that? 10 dollars? Compared to 80 - 100 for an off the shelf router, it's still a nice deal considering you can probably find a 486 for under 30 dollars, and you don't need a monitor for something like this, you could log in over SSH to do all the work on it.

I've managed to work on a machine "headless" because the power went out once, and because I couldn't turn the monitor on (It takes a lot of juice and the UPS I had was a home version that only gives you a few minutes to get it shut down) I didn't have the monitor turned on, and knew that the night before when I went to bed, I had left the machine with KDE running.

I did this:

ALT+CTRL+F5 (I knew I didn't have a log in on that one) and then did this:

root [Enter}
Password [Enter}
halt[Enter]
And shut down.

In theory you could do this on a machine acting as a router for different things, like updates.

Or keep an old monitor around hooked up in case you need to use the system console VS SSH, like upgrading a Kernel, or messing with packet filtering where you can lock yourself out of the box by accident.