SonicOS 7.1 System

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Technical Documentation > SonicOS 7.1 System > MAC IP Anti-Spoof

MAC IP Anti-Spoof

MAC and IP address-based attacks are increasingly common in today’s network security environment. These types of attacks often target a Local Area Network (LAN) and can originate from either outside or inside a network. In fact, anywhere internal LANs are somewhat exposed, such as in office conference rooms, schools, or libraries, could provide an opening to these types of attacks. These attacks also go by various names: man-in-the-middle attacks, ARP poisoning, SPITS. The MAC-IP Anti-Spoof feature lowers the risk of these attacks by providing you with different ways to control access to a network, and by eliminating spoofing attacks at OSI Layer 2/3.

The effectiveness of the MAC-IP Anti-Spoof feature focuses on two areas. The first is admission control that allows you the ability to select which devices gain access to the network. The second area is the elimination of spoofing attacks, such as denial-of-service attacks, at Layer 2. To achieve these goals, two caches of information must be built: the MAC-IP Anti-Spoof Cache, and the ARP Cache.

The MAC-IP Anti-Spoof cache validates incoming packets and determines whether they are to be allowed inside the network. An incoming packet’s source MAC and IP addresses are looked up in this cache. If they are found, the packet is allowed through. The MAC-IP Anti-Spoof cache is built through one or more of the following sub-systems:

  • DHCP Server-based leases (SonicWall’s - DHCP Server)
  • DHCP relay-based leases (SonicWall’s - IP Helper)
  • Static ARP entries
  • User created static entries

The ARP Cache is built through the following subsystems:

  • ARP packets; both ARP requests and responses
  • Static ARP entries from user-created entries
  • MAC-IP Anti-Spoof Cache

The MAC-IP Anti-Spoof subsystem achieves egress control by locking the ARP cache, so egress packets (packets exiting the network) are not spoofed by a bad device or by unwanted ARP packets. This prevents a firewall from routing a packet to the unintended device, based on mapping. This also prevents man-in-the-middle attacks by refreshing a client’s own MAC address inside its ARP cache.

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