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Is it possible to have a firewall in front of a device with a public IP address without getting in the middle of NAT? I have a server that I need to put on the internet, but I want to put a firewall in front of it. I don't want to use NAT, and what I think I need is bridging, but I don't know what hardware I would need to accomplish what I want to do. Can someone clarify and help me please? Thanks for the help! Ross

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Yes, it can be done. I do not know about other firewalls, but SonicWALL can do it with what they call transparent mode (aka bridged), configured on the LAN interface in this screenshot. In the TZ series (the model shown is a TZ190), it can be configured to bridge to the OPT (DMZ) or LAN interface, or in the PRO series to any interface except X1 (itself).

enter image description here

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I would vote you +1 and mark finished, but I don't have the reps. Thanks! This is perfect! :) – Ross Jul 6 '11 at 4:03
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Yes, it is quite possible to use a firewall on your machine without NAT. Just install a software firewall on your machine. To connect it to your network, you'll need a second network card. Just route that card to your existing network and you are good to go.

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No, that is not what I am asking. I want to have a hardware firewall in front of physical machines, but the physical machines have a public IP address not a private IP like 192.168 etc. – Ross Jul 4 '11 at 4:52
If it is another hardware device with a NIC, then that is impossible. If they have the same IP address, then they won't be able to communicate with each other. Packets leaving your server would just loop right back. What exactly are you trying to do with the server? There are countless technologies out there to solve networking problems. But you'll have to explain your situation. – surfasb Jul 4 '11 at 6:11
I've tried to explain it as best I can. I have a server configured with a public IP address. I have a firewall in front of that server. The server is still accessible via its public IP address from the outside world. Anyway, KCotreau has answered my question perfectly. Thanks, though! – Ross Jul 6 '11 at 4:03
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