I have several questions regarding hardware firewalls for servers.
1. Is there a hardware firewall that can be put inside a server case, for example if I had a 3U server chassis/case and wanted to fit a hardware firewall inside instead of renting another 1U space at the colocation center. Is this even possible? Is there such a brand of firewall that would fit inside of a case. And be connected in such a way to the server like for example a PCI card, etc. This might even be construed as a ridiculous question so please dont laugh

Thanks
2. What is the best firewall to protect a dedicated server from a DDOS attack. Does not matter if it is an external firewall or one that would perhaps fit inside of a case ( if there is such a thing).
3. What is the best way to stop a DDOS attack? ( This may not be necessarily a hardware question)