Apparatus and associated systems and methods may relate to a data traffic modification system that may modify a data stream as a function of a selected data value in the data stream, where the data value is selected from among values received into a buffer before the occurrence of a trigger condition. In an illustrative example, a buffer in a data traffic modification device may receive and temporarily store multiple data values being transferred between a source device (e.g., server) and a target device (e.g., storage area network). In some embodiments, the buffered data may contain data to be captured in response to detecting a trigger condition. The captured data, for example, may be used to generate a substitution value for another location in the data stream. Accordingly, some implementations may provide for capture of data values that precede a trigger data value within a data stream.

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