CSV files may only have a single header. All rows below the header are expected to have the same number of fields. Consider writing each event type to a different CSV. Another option is to use a single file, but in a different format such as key=value or JSON.
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The Maxmind database does not have information about internal (10.* and 192.168.*) IP addresses. You'll have to locate those addresses yourself since only your company knows where they are.
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