Справочник Пользователя для Netopia D7171 SDSL

Note the Offset is set to look at a value six bytes into the packet, the Value is 0000C8E395000000 and 
the Mask is set to match only the hexidecimal digits we're interested in -- the ones that represent the MAC 
address.

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The next item that's commonly evaluated in a Generic filter is the frame type. The frame type is located at 
an offset of twelve bytes. For IP packets it has a value of 0800 (hex) and for ARP the value is 0806 (hex). 
So a filter set summar y to block all incoming IP and ARP packets looks like this:

A filter set blocking all incoming IPX requires two filter rules. One to verify the byte with offset of 12 bytes is 
less than 600 (hex) ANDed (chained with) a filter that verifies the byte offset by 14 is not equal to FFFF. 

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The filter set should look like this (with the first filter rule's chain field set to “Yes” because the packet has 
to match both rules to be qualified as an IPX packet.)

                               Add Input Filter

         Enabled:                           Yes
         Forward:                           No
         Type...                            Generic

         Value:                             0000C8E395000000
         Mask:                              FFFFFFFFFF000000
         Offset:                            6

         Compare:                           Equal

         Chain to Next Filter:              No

         ADD THIS FILTER NOW                CANCEL

Enter the packet specific information for this filter.

   +-#----Value-------------Mask--------------Offst-Compare--Chain---On?-Fwd-+
   +-------------------------------------------------------------------------+
   | 1    0800000000000000  FFFF000000000000  12    =        No      Yes No  |
   | 2    0806000000000000  FFFF000000000000  12    =        No      Yes No  |
   |                                                                         |
   |                                                                         |

   +-#----Value-------------Mask--------------Offst-Compare--Chain---On?-Fwd-+
   +-------------------------------------------------------------------------+
   | 1    0600000000000000  FFFF000000000000  12    <        Yes     Yes     |
   | 2    FFFF000000000000  FFFF000000000000  14    =        No      Yes No  |
   |                                                                         |