gomitmproxy

gomitmproxy

gomitmproxy is a robust Golang implementation of a man-in-the-middle proxy, inspired by go-mitmproxy and mitmproxy. It serves as a versatile, standalone tool for intercepting, inspecting, modifying, and replaying HTTP/HTTPS traffic. Built with performance and extensibility in mind, it supports a powerful plugin system, making it easy to extend functionality using Go.

✨ Key Features

• Traffic Interception: Intercepts HTTP & HTTPS traffic with full man-in-the-middle (MITM) capabilities.
• Web Interface: A built-in web UI (default port 9081) for real-time traffic monitoring and inspection.
• Addon System: Highly extensible architecture allowing you to write Go plugins to modify requests/responses on the fly.
• TLS Fingerprinting: Emulate different browser fingerprints (JA3/JA4) to evade bot detection.
• Flow Storage & Search: Save intercepted traffic to disk (DuckDB) and perform full-text search (Bleve) locally.
• Map Remote: Rewrite request URLs to redirect traffic to different destinations.
• Map Local: Serve local files instead of fetching from the remote server.
• HTTP/2 Support: Fully compatible with HTTP/2 protocol.
• Certificate Management: Automatic generation and management of CA certificates, compatible with mitmproxy.

📦 Installation

Using go install (Recommended)

go install github.com/retutils/gomitmproxy/cmd/go-mitmproxy@latest

From Source

git clone https://github.com/retutils/gomitmproxy.git
cd gomitmproxy
go mod tidy
go build -o gomitmproxy ./cmd/go-mitmproxy

🚀 Command Line Usage

Start the proxy server with default settings (Proxy: :9080, Web UI: :9081):

gomitmproxy

Common Flags

View all available options:

gomitmproxy -h

Certificate Setup

After the first run, the CA certificate is generated at ~/.mitmproxy/mitmproxy-ca-cert.pem. You must install and trust this certificate on your client device to intercept HTTPS traffic. See mitmproxy docs for installation instructions.

🛠 Feature Details

1. TLS Fingerprinting

Evade fingerprint-based blocking by mimicking real browsers.

Usage:

gomitmproxy -tls_fingerprint chrome

Supported presets: chrome, firefox, edge, safari, 360, qq, ios, android, random, client.

Custom Fingerprints: You can capture a real fingerprint and use it later.

1. Capture: gomitmproxy -fingerprint_save my_fingerprint
2. List: gomitmproxy -fingerprint_list
3. Use: gomitmproxy -tls_fingerprint my_fingerprint

2. Flow Storage & Search

Persist traffic history and search through it using a local database usage DuckDB and Bleve.

Enable Storage:

gomitmproxy -storage_dir ./data

Search (HTTPQL): You can search the stored flows using the powerful HTTPQL syntax.

Available fields:

• req.method
• req.host
• req.path
• req.query
• req.body
• resp.code
• resp.body

Operators: eq, ne, cont, ncont, like (glob), regex, gt, lt, gte, lte.

# Search for POST requests
gomitmproxy -storage_dir ./data -search 'req.method.eq:"POST"'

# Search for requests containing "api" in host and 200 OK response
gomitmproxy -storage_dir ./data -search 'req.host.cont:"api" AND resp.code.eq:200'

# Search request body for a specific user ID
gomitmproxy -storage_dir ./data -search 'req.body.cont:"user_id:12345"'

# Search response body using wildcard (glob)
gomitmproxy -storage_dir ./data -search 'resp.body.like:"*error*"'

See HTTPQL Documentation for full syntax reference.

3. Map Remote

Rewrite request locations to different destinations based on rules.

Config File (map_remote.json):

{
  "enable": true,
  "items": [
    {
      "from": { "path": "/old-api/*" },
      "to": {
        "protocol": "https",
        "host": "new-api.example.com",
        "path": "/v2/"
      },
      "enable": true
    }
  ]
}

Run: gomitmproxy -map_remote map_remote.json

4. Map Local

Serve local files for specific requests.

Config File (map_local.json):

{
  "enable": true,
  "items": [
    {
      "from": { "url": "https://example.com/style.css" },
      "to": { "path": "./local_style.css" },
      "enable": true
    },
    {
      "from": { "path": "/static/*" },
      "to": { "path": "./local_static_dir" },
      "enable": true
    }
  ]
}

Run: gomitmproxy -map_local map_local.json

📚 Library Usage

You can use gomitmproxy as a library to build custom proxy tools.

Basic Example

package main

import (
	"log"
	"github.com/retutils/gomitmproxy/proxy"
)

func main() {
	opts := &proxy.Options{
		Addr:              ":9080",
		StreamLargeBodies: 1024 * 1024 * 5,
        SslInsecure:       true,
	}

	p, err := proxy.NewProxy(opts)
	if err != nil {
		log.Fatal(err)
	}

	log.Fatal(p.Start())
}

Developing Custom Addons (Plugins)

Extend functionality by implementing the Addon interface.

package main

import (
    "log"
    "github.com/retutils/gomitmproxy/proxy"
)

// Define your addon
type MyAddon struct {
    proxy.BaseAddon // optional: embed BaseAddon to avoid implementing all methods
}

// Implement methods you need
func (a *MyAddon) Request(f *proxy.Flow) {
    if f.Request.URL.Host == "example.com" {
        f.Request.Header.Add("X-Intercepted-By", "Go-Mitmproxy")
    }
}

func main() {
    opts := &proxy.Options{Addr: ":9080"}
    p, _ := proxy.NewProxy(opts)

    // Register your addon
    p.AddAddon(&MyAddon{})

    p.Start()
}

See examples for more detailed use cases.

📄 License

MIT License