extensions/libxt_length.man - platform/external/iptables - Git at Google

 This module matches the length of the layer-3 payload (e.g. layer-4 packet)
 of a packet against a specific value
 or range of values.
 .TP
 [\fB!\fP] \fB\-\-length\fP \fIlength\fP[\fB:\fP\fIlength\fP]
	This module matches the length of the layer-3 payload (e.g. layer-4 packet)
	of a packet against a specific value
	or range of values.
	.TP
	[\fB!\fP] \fB\-\-length\fP \fIlength\fP[\fB:\fP\fIlength\fP]