Decoded representation of the 24-byte pcap global header.
Field semantics follow the libpcap reference layout. magic distinguishes
the byte order and timestamp resolution; the remaining fields describe the
capture environment.
magic: number
Magic number identifying byte order and timestamp resolution.
versionMajor: number
Major version of the file format (currently 2).
versionMinor: number
Minor version of the file format (currently 4).
thisZone: number
GMT-to-local-time correction in seconds; almost always 0 in modern files.
sigFigs: number
Timestamp accuracy; conventionally 0.
snapLen: number
Maximum captured length per packet, in bytes.