Collecting traffic through my modem

Question

HI,
I am new to java . i wanted to know how i could collect packets passing through my modem.
cheers
spradigy

Answer 1

"Signal" is in dBm, or dB referenced to 1 milliwatt. The numbers are negative, so smaller (toward positive) is stronger. I'm getting passable service back here in my office with -80 dBm, but my computer in the living room, right next to the airport, is running -55, much stronger. You can use this number to help decide where to place your airport and your computer.
Noise is also dBm, and smaller (more negative) is better. This number suggests when your computer or your airport might be near a source of noise, like a motor, flourescent lamp or another radio device.
A number you can calculate real easily is signal-to-noise ratio, or SNR. Because dBms are logarithms of power you can subtract them to get their ratio of power, in dB (not dBm; the m's cancel). You do have to be careful with the signs because you are subtracting negative numbers, but it's still easier than dividing. With a signal of -80 dBm and noise of -90 dBm, my SNR will be (-80) - (-90) = (-80) + 90 = +10 dB, which is plenty strong.
Rate looks like it might be packets per minute, averaged over several minutes. This is the one I was looking for.
We run a public Wi-Fi service here at the house, no password required. We don't mind people in the neighborhood hookin' up to the internet on our service. Lord knows I've been grateful to have had a free link now and then, and it don't take nothin' from nobody. It's like offerin' a free drink of water.
But then, there's always the chance of things gettin' out of hand. Every now and then when our service here in the house seems a little slow, I've wondered whether it could be because a bunch of folks parked in the street were all playing World of Warcraft at the same time. Now, with this tool, I can look and see.
I might point out that DHCP clients persist for several hours. So, if you see an IP address or a MAC address you don't recognize, you still have to look under "Wireless Clients" to see whether he might not have driven off a while ago.
--Gil