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modified post fd80 by Anonymous on Sun 26th Feb 2023 21:39
original post d0b0a by Anonymous on Sun 26th Feb 2023 17:57
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#!/usr/bin/ksh93

1	1		#!/usr/bin/ksh93
2	2
3	3		#
4		-	# find_free_tcp_port1.ksh - find a free tcp port
	4	+	# list_active_local_tcp_ports1.ksh - list port numbers of local TCP connections
5	5		#
6	6		# Written by Roland Mainz <roland.mainz@nrubsig.org>
7	7		#
8	8
9	9		#
10	10		# simple netstat -n parser
11	11		#
12	12		function netstat_list_connections
13	13		{
14	14		# fixme: should be set -o nounset clean
15	15		nameref data=$1
16	16
17	17		typeset -a data.connections
18	18
19	19		typeset nsout="$(LC_ALL='POSIX' netstat -n)"
20	20
21	21		while read i ; do
22	22		leftover="${i/~(Elrx)
23	23		(?: # non-capturing group
24	24		#
25	25		# regex group for tcpudp
26	26		#
27	27		(tcp\|tcp6\|udp) # Proto
28	28		[[:space:]]+
29	29		([[:digit:]]+) # Recv-Q
30	30		[[:space:]]+
31	31		([[:digit:]]+) # Send-Q
32	32		[[:space:]]+
33	33		([^[:space:]]+) # Local Address
34	34		[[:space:]]+
35	35		([^[:space:]]+) # Foreign Address
36	36		[[:space:]]+
37	37		([^[:space:]]+) # State
38	38		\|
39	39		#
40	40		# regex for unix
41	41		#
42	42		(unix) # Proto
43	43		[[:space:]]+
44	44		([[:digit:]]+) # RefCnt
45	45		[[:space:]]+
46	46		(\[.+\]) # Flags
47	47		[[:space:]]+
48	48		([^[:space:]]+) # Type
49	49		[[:space:]]+
50	50		([^[:space:]]*?) # State
51	51		[[:space:]]+
52	52		([[:digit:]]+) # I-Node
53	53		(?:
54	54		# Path is optional
55	55		\|
56	56		[[:space:]]+
57	57		([^[:space:]]+) # Path
58	58		)
59	59		)
60	60		/X}"
61	61
62	62		# if the regex above did not match then .sh.match
63	63		# remains untouched, so we might see data from the
64	64		# previous round.
65	65		# so we check the "leftover" var whether it just
66	66		# contains the dummy value of "X" to indicate a
67	67		# successful regex match
68	68		if [[ "$leftover" == 'X' ]] ; then
69	69		#print -v .sh.match
70	70
71	71		if [[ "${.sh.match[1]}" != '' ]] ; then
72	72		data.connections+=(
73	73		typeset proto="${.sh.match[1]}"
74	74		typeset recv_q="${.sh.match[2]}"
75	75		typeset send_q="${.sh.match[3]}"
76	76		typeset local_address="${.sh.match[4]}"
77	77		typeset foreign_address="${.sh.match[5]}"
78	78		typeset state="${.sh.match[6]}"
79	79		)
80	80		elif [[ "${.sh.match[7]}" != '' ]] ; then
81	81		data.connections+=(
82	82		typeset proto="${.sh.match[7]}"
83	83		typeset refcnt="${.sh.match[8]}"
84	84		typeset flags="${.sh.match[9]}"
85	85		typeset type="${.sh.match[10]}"
86	86		typeset state="${.sh.match[11]}"
87	87		typeset inode="${.sh.match[12]}"
88	88		typeset path="${.sh.match[13]}"
89	89		)
90	90		fi
91	91		else
92	92		:
93		-	printf "leftover=%q\n" "${leftover}"
	93	+	#printf "leftover=%q\n" "${leftover}"
94	94		fi
95	95		done <<<"$nsout"
96	96
97	97		return 0
98	98		}
99	99
100		-	function main
	100	+	function list_active_local_tcp_connections
101	101		{
	102	+	nameref ar=$1
102	103		compound c
103		-	netstat_list_connections c
	104	+	integer port
113	105
114		-	}
115	106
116		-	main
	107	+	netstat_list_connections c \|\| return 1
117		-	# EOF.
	108	+	# print -v c
118	109
119		-
	110	+	[[ -v ar ]] \|\| typeset -a ar
120	111
121		-
	112	+	for i in "${!c.connections[@]}" ; do
122		-
	113	+	nameref n=c.connections[$i]
123	114
124		-
	115	+	# look for only for TCP connections which match
125		-
	116	+	# 127.0.. or IPv6 ::1
126		-
	117	+	if [[ "${n.proto}" == ~(El)tcp && \
127		-
	118	+	"${n.local_address}" == ~(Elr)(127\.0\..+\|::1):[[:digit:]]+ ]] ; then
128	119
129		-
	120	+	port="${n.local_address##*:}"
130		-
	121	+	#printf $"port = %d\n" port
131	122
132		-
	123	+	(( ar[port]=1 ))
133		-
	124	+	fi
134		-
	125	+	done
135	126
136		-
	127	+	return 0
137		-
	128	+	}
138	129
139		-
	130	+	function main
140		-
	131	+	{
141		-
	132	+	compound c=( integer -a ar )
142	133
143		-
	134	+	list_active_local_tcp_connections c.ar \|\| return 1
144	135
145		-
	136	+	# print -v c
146		-
	137	+	printf $"%d\n" "${!c.ar[@]}"
147	138
148		-
	139	+	return 0
149		-
	140	+	}
150	141
151		-
	142	+	# main entry point
152		-
	143	+	main
153		-
	144	+	exit $?
154		-
	145	+	# EOF.