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header

The control information at the front of a packet: addresses, lengths, flags.

A header is the fixed-format block a protocol layer adds in front of its payload, carrying the fields that layer needs, such as addresses, ports, lengths and flags.

Examples

  • The IP header on a greenhouse reading holds the source 192.168.1.37 and destination 192.168.1.10, plus the packet's length.

  • The TCP header in front of the payload carries the ports, here from 49152 to the broker's 1883.

See also

packet encapsulation port
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