This file is indexed.

/etc/dhcp/dhclient-exit-hooks.d/rfc3442-classless-routes is in isc-dhcp-client 4.1.ESV-R4-0ubuntu5.

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
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
# set classless routes based on the format specified in RFC3442
# e.g.:
#   new_rfc3442_classless_static_routes='24 192 168 10 192 168 1 1 8 10 10 17 66 41'
# specifies the routes:
#   192.168.10.0/24 via 192.168.1.1
#   10.0.0.0/8 via 10.10.17.66.41

RUN="yes"


if [ "$RUN" = "yes" ]; then
	if [ -n "$new_rfc3442_classless_static_routes" ]; then
		if [ "$reason" = "BOUND" ] || [ "$reason" = "REBOOT" ]; then

			set -- $new_rfc3442_classless_static_routes

			while [ $# -gt 0 ]; do
				net_length=$1

				case $net_length in
					32|31|30|29|28|27|26|25)
						net_address="${2}.${3}.${4}.${5}"
						gateway="${6}.${7}.${8}.${9}"
						shift 9
						;;
					24|23|22|21|20|19|18|17)
						net_address="${2}.${3}.${4}.0"
						gateway="${5}.${6}.${7}.${8}"
						shift 8
						;;
					16|15|14|13|12|11|10|9)
						net_address="${2}.${3}.0.0"
						gateway="${4}.${5}.${6}.${7}"
						shift 7
						;;
					8|7|6|5|4|3|2|1)
						net_address="${2}.0.0.0"
						gateway="${3}.${4}.${5}.${6}"
						shift 6
						;;
					0)	# default route
						net_address="0.0.0.0"
						gateway="${2}.${3}.${4}.${5}"
						shift 5
						;;
					*)	# error
						return 1
						;;
				esac

				if [ "$net_length" -eq 32 ]; then
					/sbin/route add -host "${net_address}" gw "${gateway}"
				else
					/sbin/route add -net "${net_address}/${net_length}" gw "${gateway}"
				fi
			done
		fi
	fi
fi