/usr/src/xtables-addons-1.40/xt_lscan.Kconfig is in xtables-addons-dkms 1.40-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 | config NETFILTER_XT_MATCH_LSCAN
	tristate '"lscan" match support'
	depends on NETFILTER_XTABLES && NETFILTER_ADVANCED
	---help---
	The LSCAN match allows to match on the basic types of nmap
	scans: Stealth Scan, SYN scan and connect scan. It can also match
	"grab-only" connections, i.e. where data flows in only one
	direction.
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