timestamp microseconds(4Byte)
data link type(4Byte)
struct pcap_hdr
actual length of packet(4Byte)
struct pcaprec_hdr
timestamp seconds(4 Byte)
packet data
accuracy of timestamps(4Byte)
GMT to local correction(4Byte)
magic number(4 Byte)
number of octets of packet saved in file(4Byte)
major version number(2Byte)
minor version number(2Byte)
