ActiveArmor is a hardware firewall designed by Nvidia

NVIDIA

Nvidia is an American global technology company based in Santa Clara, California. Nvidia is best known for its graphics processors . Nvidia and chief rival AMD Graphics Techonologies have dominated the high performance GPU market, pushing other manufacturers to smaller, niche roles...

 that's built into their higher range nForce4 Ultra

NForce4

The nForce4 is a motherboard chipset released by Nvidia in October, 2004. The chipset supports AMD 64-bit processors and Intel Pentium 4 LGA 775 processors.-nForce4/nForce4-4x:...

 chipset motherboard

Motherboard

In personal computers, a motherboard is the central printed circuit board in many modern computers and holds many of the crucial components of the system, providing connectors for other peripherals. The motherboard is sometimes alternatively known as the mainboard, system board, or, on Apple...

s.

It can reduce CPU load by making some simple layer 2

OSI model

The Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...

 checks on incoming packets and discarding obviously malicious packets before they are sent to the CPU. It is an effective protection against some same subnet based attacks such as ARP poisoning, rogue DHCP

Rogue DHCP

A rogue DHCP server is a DHCP server on a network which is not under the administrative control of the network staff. It is a network device such as a modem or a router connected to the network by a user who may be either unaware of the consequences of their actions or may be knowingly using it...

 servers and spoofed

Spoofing attack

In the context of network security, a spoofing attack is a situation in which one person or program successfully masquerades as another by falsifying data and thereby gaining an illegitimate advantage.- Spoofing and TCP/IP :...

 MAC address

MAC address

A Media Access Control address is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used for numerous network technologies and most IEEE 802 network technologies, including Ethernet...

es.

Unfortunately it is essentially broken in its current implementation, with serious issues with data corruption and memory leak

Memory leak

A memory leak, in computer science , occurs when a computer program consumes memory but is unable to release it back to the operating system. In object-oriented programming, a memory leak happens when an object is stored in memory but cannot be accessed by the running code...

. It is so bad that programs such as µTorrent actually warn users at start up to disable it.