Comment by Jaap for You are reading raw packet data through the use of Pcap4J, but are not writing PCAP format files. You simply dump the raw packet data into a file. You need to add the file format structures are well.

Oh, I see. It's encapsulating `pcap_dump_fopen()` then. Still not seeing `dumpRaw` encapsulating `pcap_dump()`, where's the packet header info (in particular the size)?