Can linux firewall traffic not necessarily intended for it (promisc mode)?
Simple question for you linux firewall gurus out there:
Can linux (running in promiscuous mode) intercept and block packets via firewall rules (basically block inappropriate packets via a firewall, but the traffic isn't physically going through linux (say, in a traditional dual-nic setup)?
I want linux to firewall incoming and outgoing traffic from our LAN to our WAN connection, but I don't want the connection physically broken if the linux box happens to go down.
In other words, I want traffic to do this: LAN -> linux -> WAN, without the linux step being a major point of failure from a hardware point of view.
The problem is that our WAN router doesn't have the capability to diplicate all I/O to one host, so I thought that I might be able to rig something with an old hub we have (put the hub between the WAN router and our LAN switches, and put the linux box on that hub).
I know there are fancy proxy/firewall systems (expensive network appliances) that do similar things, but this is a different situation.
I'm working with a very tight budget (we're a very small operation) and trying to improvise with what hardware we have on hand.
Is there a way to accomplish this?