added setup to handle ARP spoofed traffic

Author: shadowy-pycoder

README.md

@@ -20,6 +20,7 @@
 - [Transparent proxy](#transparent-proxy)
   - [redirect (via NAT and SO_ORIGINAL_DST)](#redirect-via-nat-and-so_original_dst)
   - [tproxy (via MANGLE and IP_TRANSPARENT)](#tproxy-via-mangle-and-ip_transparent)
+  - [ARP spoofing](#arp-spoofing)
 - [Traffic sniffing](#traffic-sniffing)
   - [JSON format](#json-format)
   - [Colored format](#colored-format)
@@ -97,7 +98,7 @@ You can download the binary for your platform from [Releases](https://github.com
 Example:
 
 ```shell
-HPTS_RELEASE=v1.8.3; wget -v https://github.com/shadowy-pycoder/go-http-proxy-to-socks/releases/download/$HPTS_RELEASE/gohpts-$HPTS_RELEASE-linux-amd64.tar.gz -O gohpts && tar xvzf gohpts && mv -f gohpts-$HPTS_RELEASE-linux-amd64 gohpts && ./gohpts -h
+HPTS_RELEASE=v1.8.4; wget -v https://github.com/shadowy-pycoder/go-http-proxy-to-socks/releases/download/$HPTS_RELEASE/gohpts-$HPTS_RELEASE-linux-amd64.tar.gz -O gohpts && tar xvzf gohpts && mv -f gohpts-$HPTS_RELEASE-linux-amd64 gohpts && ./gohpts -h
 ```
 
 Alternatively, you can install it using `go install` command (requires Go [1.24](https://go.dev/doc/install) or later):
@@ -164,6 +165,7 @@ Options:
   -T        Address of transparent proxy server (no HTTP)
   -M        Transparent proxy mode: (redirect, tproxy)
   -auto     Automatically setup iptables for transparent proxy (requires elevated privileges)
+  -arp      Automatically setup iptables to proxy ARP spoofed traffic (use tools like bettercap to perform actual attack)
   -mark     Set mark for each packet sent through transparent proxy (Default: redirect 0, tproxy 100)
 ```
 
@@ -479,6 +481,25 @@ else
 fi
 ```
 
+### ARP spoofing
+
+`GoHPTS` can be used with tools like [Bettercap](https://github.com/bettercap/bettercap) to proxy ARP spoofed traffic.
+
+Run the proxy with `-arp` flag
+
+```shell
+ssh remote -D 1080 -Nf
+sudo env PATH=$PATH gohpts -d -T 8888 -M tproxy -sniff -body -auto -mark 100 -arp
+```
+
+Run `bettercap`
+
+```shell
+sudo bettercap -eval "set net.probe on;set net.recon on;arp.spoof on"
+```
+
+Check proxy logs for traffic from other devices from your LAN
+
 ## Traffic sniffing
 
 [[Back]](#table-of-contents)

cmd/gohpts/cli.go

@@ -61,6 +61,7 @@ const usageTproxy string = `
   -T        Address of transparent proxy server (no HTTP)
   -M        Transparent proxy mode: (redirect, tproxy)
   -auto     Automatically setup iptables for transparent proxy (requires elevated privileges)
+  -arp      Automatically setup iptables to proxy ARP spoofed traffic (use tools like bettercap to perform actual attack)
   -mark     Set mark for each packet sent through transparent proxy (Default: redirect 0, tproxy 100)
 `
 
@@ -113,6 +114,12 @@ func root(args []string) error {
 			0,
 			"Set mark for each packet sent through transparent proxy (Default: redirect 0, tproxy 100)",
 		)
+		flags.BoolVar(
+			&conf.ARP,
+			"arp",
+			false,
+			"Automatically setup iptables to proxy ARP spoofed traffic (use tools like bettercap to perform actual attack)",
+		)
 	}
 	flags.StringVar(&conf.LogFilePath, "logfile", "", "Log file path (Default: stdout)")
 	flags.BoolVar(&conf.Debug, "d", false, "Show logs in DEBUG mode")
@@ -172,6 +179,11 @@ func root(args []string) error {
 			return fmt.Errorf("-mark requires -t or -T flag")
 		}
 	}
+	if seen["arp"] {
+		if !seen["auto"] {
+			return fmt.Errorf("-arp requires -auto flag")
+		}
+	}
 	if seen["f"] {
 		for _, da := range []string{"s", "u", "U", "c", "k", "l"} {
 			if seen[da] {

gohpts.go

@@ -97,6 +97,7 @@ type Config struct {
 	TProxyMode     string
 	Auto           bool
 	Mark           uint
+	ARP            bool
 	LogFilePath    string
 	Debug          bool
 	JSON           bool
@@ -120,6 +121,7 @@ type proxyapp struct {
 	tproxyMode     string
 	auto           bool
 	mark           uint
+	arp            bool
 	user           string
 	pass           string
 	proxychain     chain
@@ -1361,10 +1363,53 @@ func (p *proxyapp) applyRedirectRules() string {
 	cmdForward.Stdout = os.Stdout
 	cmdForward.Stderr = os.Stderr
 	_ = cmdForward.Run()
+	if p.arp {
+		cmdClear := exec.Command("bash", "-c", `
+        set -ex
+		iptables -t filter -F GOHPTS 2>/dev/null || true
+		iptables -t filter -D FORWARD -j GOHPTS  2>/dev/null || true
+		iptables -t filter -X GOHPTS  2>/dev/null || true
+        `)
+		cmdClear.Stdout = os.Stdout
+		cmdClear.Stderr = os.Stderr
+		if err := cmdClear.Run(); err != nil {
+			p.logger.Fatal().Err(err).Msg("Failed while configuring iptables. Are you root?")
+		}
+		iface, err := getDefaultInterface()
+		if err != nil {
+			p.logger.Fatal().Err(err).Msg("failed getting default network interface")
+		}
+		cmdForward := exec.Command("bash", "-c", fmt.Sprintf(`
+		set -ex
+		iptables -t filter -N GOHPTS 2>/dev/null
+		iptables -t filter -F GOHPTS
+		iptables -t filter -A FORWARD -j GOHPTS
+		iptables -t filter -A GOHPTS -i %s -j ACCEPT
+		iptables -t filter -A GOHPTS -o %s -j ACCEPT
+		`, iface.Name, iface.Name))
+		cmdForward.Stdout = os.Stdout
+		cmdForward.Stderr = os.Stderr
+		if err := cmdForward.Run(); err != nil {
+			p.logger.Fatal().Err(err).Msg("Failed while configuring iptables. Are you root?")
+		}
+	}
 	return string(output)
 }
 
 func (p *proxyapp) clearRedirectRules(output string) error {
+	if p.arp {
+		cmdClear := exec.Command("bash", "-c", `
+        set -ex
+		iptables -t filter -F GOHPTS 2>/dev/null || true
+		iptables -t filter -D FORWARD -j GOHPTS  2>/dev/null || true
+		iptables -t filter -X GOHPTS  2>/dev/null || true
+        `)
+		cmdClear.Stdout = os.Stdout
+		cmdClear.Stderr = os.Stderr
+		if err := cmdClear.Run(); err != nil {
+			p.logger.Fatal().Err(err).Msg("Failed while configuring iptables. Are you root?")
+		}
+	}
 	var cmd *exec.Cmd
 	switch p.tproxyMode {
 	case "redirect":
@@ -1701,7 +1746,7 @@ func New(conf *Config) *proxyapp {
 	p.tproxyMode = conf.TProxyMode
 	tproxyonly := conf.TProxyOnly != ""
 	if tproxyonly {
-		if p.tproxyMode == "tproxy" {
+		if p.tproxyMode != "" {
 			p.tproxyAddr, err = getFullAddress(conf.TProxyOnly, true)
 			if err != nil {
 				p.logger.Fatal().Err(err).Msg("")
@@ -1713,7 +1758,7 @@ func New(conf *Config) *proxyapp {
 			}
 		}
 	} else {
-		if p.tproxyMode == "tproxy" {
+		if p.tproxyMode != "" {
 			p.tproxyAddr, err = getFullAddress(conf.TProxy, true)
 			if err != nil {
 				p.logger.Fatal().Err(err).Msg("")
@@ -1739,6 +1784,12 @@ func New(conf *Config) *proxyapp {
 	if p.mark == 0 && p.tproxyMode == "tproxy" {
 		p.mark = 100
 	}
+	p.arp = conf.ARP
+	if p.arp && runtime.GOOS != "linux" {
+		p.logger.Fatal().Msg("ARP setup is available only for linux system")
+	} else if p.arp && !p.auto {
+		p.logger.Fatal().Msg("ARP setup requires auto configuration")
+	}
 	var addrHTTP, addrSOCKS, certFile, keyFile string
 	if conf.ServerConfPath != "" {
 		var sconf serverConfig

tproxy_linux.go

@@ -4,11 +4,13 @@
 package gohpts
 
 import (
+	"bufio"
 	"context"
 	"errors"
 	"fmt"
 	"net"
 	"net/netip"
+	"os"
 	"strings"
 	"sync"
 	"syscall"
@@ -257,3 +259,23 @@ func getBaseDialer(timeout time.Duration, mark uint) *net.Dialer {
 	}
 	return dialer
 }
+
+func getDefaultInterface() (*net.Interface, error) {
+	f, err := os.Open("/proc/net/route")
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	defaultInterface := ""
+	scanner := bufio.NewScanner(f)
+	for scanner.Scan() {
+		line := scanner.Text()
+		fields := strings.Fields(line)
+		if len(fields) >= 2 && fields[1] == "00000000" {
+			defaultInterface = fields[0]
+			break
+		}
+	}
+	return net.InterfaceByName(defaultInterface)
+}

tproxy_nonlinux.go

@@ -4,6 +4,7 @@
 package gohpts
 
 import (
+	"fmt"
 	"net"
 	"sync"
 	"syscall"
@@ -46,3 +47,7 @@ func getBaseDialer(timeout time.Duration, mark uint) *net.Dialer {
 	_ = mark
 	return &net.Dialer{Timeout: timeout}
 }
+
+func getDefaultInterface() (*net.Interface, error) {
+	return nil, fmt.Errorf("not implemented")
+}

version.go

@@ -1,3 +1,3 @@
 package gohpts
 
-const Version string = "gohpts v1.8.3"
+const Version string = "gohpts v1.8.4"