I'm trying to set up a snort sensor at work with two NIC's - one listening outside the firewall with no ip address, and another inside the firewall which is how traffic will be moved off of the box. Since I'm using a linux box, the obvious way to make the outside interface silent is to not assign it an IP address. This means that it is impossible for this machine to respond to requests on its external interface. However, due to the fact that this machine will bridge the firewall, we're looking for a hardware solution as well. Are there any devices out there that allow an ethernet interface to be listen only? Thanks for the help.