This module matches the length of a packet against a specific value or range of values.

[!] --length length[:length]
    Match exact length or length range.

--layer3
    Match the layer3 frame size (e.g. IPv4/v6 header plus payload).

--layer4
    Match the layer4 frame size (e.g. TCP/UDP header plus payload).

--layer5
    Match the layer5 frame size (e.g. TCP/UDP payload, often called layer7).

If no --layer* option is given, --layer3 is assumed by default. Note that using --layer5 may not match a packet if it is not one of the recognized types (currently TCP, UDP, UDPLite, ICMP, AH and ESP) or which has no 5th layer.