wildcard Filter

1.3.6.1.4.1.11.2.14.3.5.2

This object contains the binary value used to filter frames. The data in the frame at the offset specified by the Wildcard offsets is XOR'ed with this object after AND'ing with the Wildcard Mask. If zero result occurs, the packet is discarded (filtered). Suppose the user specifies the following values: data: 11001010 10101010 10101010 10101010 mask: 11100000 00000000 00000000 00000000 filter: 11100000 00000000 00000000 00000000 AND'ing data with the mask gives: 11000000 00000000 00000000 00000000 XOR'ing that value with the filter gives: 00100000 00000000 00000000 00000000 The non-zero result indicates no match (don't discard). Another example: data: 10011010 10101010 10101010 10101010 mask: 10010000 00000000 00000000 00000000 filter: 10010000 00000000 00000000 00000000 AND'ing data with the mask gives: 10010000 00000000 00000000 00000000 XOR'ing that value with the filter gives: 00000000 00000000 00000000 00000000 A zero result indicates a match, so we discard (filter) the packet. The filter AND'ed with the mask must equal the filter. This is an example of a legal filter/mask pair: filter: 00010000 00000000 00000000 00000000 mask: 10010000 00000000 00000000 00000000 AND'ed: 00010000 00000000 00000000 00000000 (equals filter) Another way of saying this: if a mask bit is zero, the corresponding filter bit must be zero. The following would be an illegal pair: filter: 01110000 00000000 00000000 00000000 mask: 10010000 00000000 00000000 00000000 AND'ed: 00010000 00000000 00000000 00000000 ( != filter)