Pcap packets, the ones that were retrieved using libpcap library, also maintain a reference to a separate PcapHeader class. The baseclass JPacket abstracts that information away using a JCaptureHeader interface, but it is also possible to work directly with the PcapHeader class. It is peered with native C structure defined in libpcap library itself struct pcap_pkthdr. It provides information such as packet captured length, original length and capture timestamp.

Most user's do not need to deal with this detail and is sufficient to work with JCaptureHeader interface.