This might be a little odd.

I'm trying to set up my Debian sniffer to sniff all the traffic leaving the network to the Internet. The setup is the DSL router, the switch and VoIP, and another switch. The router plugs into one switch, and everything else plugs into another switch which plugs into the switch the DSL router is plugged into. There is a problem, I have VoIP and if I replace the switch the DSL router is plugged into with a hub and I try to ping a computer on my LAN it will ring busy. Since that didn't work, I though that setting up the sniffer box to do some routing and remove the switch that the DSL router is connected directly to the Debian machine.

Here is how I currently have it set up (the IP addresses are just for reference):

eth0(goes to router): 172.69.1.180
eth1(goes to LAN): 172.69.1.100
DSL Router(LAN IP address):172.69.1.1

At times I'm able to get my PC to talk to both interfaces, and then if I switch the cables around, nothing will talk. And sometimes if I have it set up backwards it talks, then put it the way it should be it doesn't talk. But no matter what, the PC will never talk to the DSL router. The Debian machine like before will talk to the DSL router, but then it won't talk to the LAN, or it will talk to the LAN, but not the DSL router.

Once I get the Debian machine to talk to the LAN and the DSL router, what options are there if my computers don't talk to my gateway(DSL router)?

Or if I don't manage to get the computer to talk to the DSL router, what options are there to get that to work?

Thanks!

Not exactly what you were asking, but the best way to go about this would be to construct a passive Ethernet tap.

Basically, this is a box that allows data to pass through it transparently, data goes through it as if it was a regular patch cable. The trick is, the box also has tap ports which are tied in to the RX pair in the cable. This means that devices connected to the tap ports can listen to anything happening over the network it is connected to, without the risk of contamination.

Putting one of these devices between your DSL modem and first switch would allow you to sniff all traffic going to the Internet without any of the devices on the network being able to tell.

That's really nifty! I don't have a Ethernet housing though.