3. Configuring the DSL Router
Ethernet Type Filtering
Ethernet Type filtering (Ethertype) does not apply when the DSL router is in
MAC frames can be filtered based on the:
SNAP Ethernet field in the 802.3 header.
Protocol type field in the DIX Ethernet header.
For Ethertype filters, the rules are applied in the order in which they were configured. For additional information about Ethertype filters, refer to the Hotwire MVL, ReachDSL, RADSL, IDSL, and SDSL Cards, Models 8310, 8312/8314, 8510/8373/8374, 8303/8304, and 8343/8344, User’s Guide.
Land Bug/Smurf Attack Prevention
Land Bug and Smurf Attack prevention are enhanced firewall features provided by the router.
Land Bug – The router drops all packets received on its DSL or Ethernet interface when the source IP address is the same as the destination IP address. This prevents the device from being kept busy by constantly responding to itself.
Smurf Attack – The router does not forward directed broadcasts on its DSL and Ethernet interfaces, or send an ICMP echo reply to the broadcast address. This ensures that a legitimate user will be able to use the network connection even if ICMP echo/reply (smurf) packets are sent to the broadcast address.
November 2003 |