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comparison src/netcat.go @ 10:b0784443ed87

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add netcat and unsleep.
author pyon@macmini
date Sat, 04 Nov 2017 11:07:50 +0900
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9:54a75ff1c288 10:b0784443ed87
1 // OK : windows -> osx
2 // Not OK : osx -> windows
3 // OK : osx, win <-> yahoo.com
4 /*
5 Netcat
6
7 -v verbose
8 -vv very verbose
9 -w timeout [ -w 2 2seconds ]
10 -i interval
11 -s local source address
12 -z zero-I/O mode ( for portscan )
13 -u with UDP ( default use TCP )
14 -n don't resolve name/address
15 -d stealth mode ( don't read from stdin )
16 -l listen mode ( once )
17 -L listen mode ( continuous )
18
19 Portscan
20 $ nc -v -z -w 1 192.168.1.1 1-140
21 $ nc -u -v -z -w 1 192.168.1.1 1-140
22
23 Web-client
24 $ nc -v www.yahoo.com 80
25
26 File transfer
27 $ nc -l 1234 > file
28 % nc hoge.com 1234 < file
29
30 Backdoor
31 C:\> nc -L -d -e cmd.exe -p 8080
32
33 */
34 package main
35
36 import (
37 "flag"
38 "fmt"
39 "io"
40 "log"
41 "net"
42 "os"
43 )
44
45 func main() {
46
47 verbose := flag.Bool( "v", false, "verbose" )
48 vverbose := flag.Bool( "vv", false, "very verbose" )
49 udp := flag.Bool( "u", false, "with udp" )
50 // interval := flag.Int( "i", 0, "interval for lines sent, port scanned" )
51 // timeout := flag.Int( "w", 7, "timeout for connects and final net reads" )
52 listen := flag.Bool( "l", false, "listen mode" )
53 zmode := flag.Bool( "z", false, "zero-I/O mode" )
54 laddr := flag.String( "s", "", "local source address" )
55 example := flag.Bool( "e", false, "print examples" )
56
57 flag.Parse()
58
59 if *example {
60 printExample()
61 os.Exit( 0 )
62 }
63
64 if flag.NArg() == 0 {
65 fmt.Fprintf( os.Stderr, "netcat v0.1 (20170604)\n" )
66 fmt.Fprintf( os.Stderr, " -h or --help option\n" )
67 os.Exit( 0 )
68 }
69
70 p := "tcp"
71 if *udp {
72 p = "udp"
73 }
74
75 if *listen {
76
77 if flag.NArg() != 1 {
78 flag.PrintDefaults()
79 os.Exit( 1 )
80 }
81
82 port := flag.Arg( 0 )
83
84 addr := getLocalIP()
85 if *laddr == "" {
86 addr = *laddr
87 }
88
89 if *verbose || *vverbose {
90 msg := fmt.Sprintf( "listening... %s:%s[%s]", addr, port, p )
91 printVerbose( msg, "" )
92 }
93
94 l, err := net.Listen( p, net.JoinHostPort( addr, port ) )
95 if err != nil {
96 log.Fatal( err )
97 }
98 defer l.Close()
99
100 conn, err := l.Accept()
101 if err != nil {
102 log.Fatal( err )
103 }
104 io.Copy( os.Stdout, conn )
105 conn.Close()
106
107 } else {
108
109 if flag.NArg() != 2 {
110 flag.PrintDefaults()
111 os.Exit( 1 )
112 }
113
114 addr := flag.Arg( 0 )
115 port := flag.Arg( 1 )
116
117 conn, err := net.Dial( p, net.JoinHostPort( addr, port ) )
118 if err != nil {
119 log.Fatal( err )
120 }
121 defer conn.Close()
122 go mustCopy( os.Stdout, conn )
123 mustCopy( conn, os.Stdin )
124 }
125
126 if *zmode {
127 /*
128 address := "" // for me.
129 port := "1-1024"
130 server := address + ":" + port
131 */
132 }
133 }
134
135 func mustCopy( dst io.Writer, src io.Reader ) {
136 if _, err := io.Copy( dst, src ); err != nil {
137 log.Fatal( err )
138 }
139 }
140
141 func printVerbose( vmsg, vvmsg string ) {
142 fmt.Fprintln( os.Stderr, vmsg, vvmsg )
143 }
144
145 func printExample() {
146 fmt.Fprintln( os.Stderr, "\n[Exaples]" )
147 fmt.Fprintln( os.Stderr, " Portscan" )
148 fmt.Fprintln( os.Stderr, " $ nc -v -z -w 1 192.168.1.1 1-140" )
149 fmt.Fprintln( os.Stderr, " $ nc -u -v -z -w 1 192.168.1.1 1-140\n" )
150 fmt.Fprintln( os.Stderr, " Web-client" )
151 fmt.Fprintln( os.Stderr, " $ nc -v www.yahoo.com 80" )
152 fmt.Fprintln( os.Stderr, " GET / HTTP/1.0[Enter]" )
153 fmt.Fprintln( os.Stderr, " [ENTER]\n" )
154 fmt.Fprintln( os.Stderr, " File transfer" )
155 fmt.Fprintln( os.Stderr, " $ nc -l 1234 > file" )
156 fmt.Fprintln( os.Stderr, " % nc hoge.com 1234 < file\n" )
157 fmt.Fprintln( os.Stderr, " Backdoor" )
158 fmt.Fprintln( os.Stderr, " C:\\> nc -L -d -e cmd.exe -p 8080" )
159 }
160
161 func getLocalIP() string {
162 addrs, err := net.InterfaceAddrs()
163 if err != nil {
164 log.Fatal( err )
165 }
166 for _, addr := range addrs {
167 if ipnet, ok := addr.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
168 if ipnet.IP.To4() != nil {
169 return ipnet.IP.String()
170 }
171 }
172 }
173 return "127.0.0.1"
174 }
175