The preferred approach for "classifying" events is to use either lookup tables or eventtypes. Lookup tables work best when there is a mapping (not necessarily one-to-one) between source and destination field values. Eventtypes allow mapping between arbitrary search statements (e.g., booleans, negations, disjunctions on keywords and fields) and categories.
Field extractions aren't ideal for this since, for efficiency, they make the assumption that the field value itself can be found in the source data. You can configure this assumption away in fields.conf, at a performance penalty.
... View more