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examples Update urls following directory rename
ext first define proxy, then run it. Now go test -race running cleanly
regretable Add missing NewRegretableReaderCloserSize
test_data move test data to its own dir
transport added error assignment on while writing to network
.gitignore .gitignore, ./all.bash more organized
LICENSE by @ancientlore email request, adding LICENSE file Line 27 is where the action happens.
actions.go fix minor typo in docs
all.bash move regret buffer to package, improve
ca.pem signer functions to generate real verifiable certificates
certs.go fixes #71, do not reuse tls.defaultTlsConfig
chunked.go gofmt
counterecryptor.go gofmt
counterecryptor_test.go gofmt
ctx.go doc: OnRequest function handler needs to return req and resp
dispatcher.go fixes #43, Hijack method to hijack CONNECT requests
doc.go Unify examples naming
https.go Adding in RemoteAddr field to requests converted from CONNECT
key.pem signer functions to generate real verifiable certificates
proxy.go Fixed typo in a potentially user-facing error message.
proxy_test.go fixes #71, ability to use known keys and certificate for MITM. Breaki…
responses.go gofmt
signer.go Do not use global GoproxyCa for certificate signing.
signer_test.go gofmt


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Package goproxy provides a customizable HTTP proxy library for Go (golang),

It supports regular HTTP proxy, HTTPS through CONNECT, and "hijacking" HTTPS connection using "Man in the Middle" style attack.

The intent of the proxy, is to be usable with reasonable amount of traffic yet, customizable and programable.

The proxy itself is simply a net/http handler.

In order to use goproxy, one should set his browser to use goproxy as an HTTP proxy. Here is how you do that in Chrome and in Firefox.

For example, the URL you should use as proxy when running ./bin/basic is localhost:8080, as this is the default binding for the basic proxy.

Mailing List

New features would be discussed on the mailing list before their development.

Latest Stable Release

Get the latest goproxy from

Why not Fiddler2?

Fiddler is an excellent software with similar intent. However, Fiddler is not as customable as goproxy intend to be. The main difference is, Fiddler is not intended to be used as a real proxy.

A possible use case that suits goproxy but not Fiddler, is, gathering statisitics on page load times for a certain website over a week. With goproxy you could ask all your users to set their proxy to a dedicated machine running a goproxy server. Fiddler is a GUI app not designed to be ran like a server for multiple users.

A taste of goproxy

To get a taste of goproxy, a basic HTTP/HTTPS transparent proxy

import (

func main() {
    proxy := goproxy.NewProxyHttpServer()
    proxy.Verbose = true
    log.Fatal(http.ListenAndServe(":8080", proxy))

This line will add X-GoProxy: yxorPoG-X header to all requests sent through the proxy

    func(r *http.Request,ctx *goproxy.ProxyCtx)(*http.Request,*http.Response) {
        return r,nil

DoFunc will process all incoming requests to the proxy. It will add a header to the request and return it. The proxy will send the modified request.

Note that we returned nil value as the response. Have we returned a response, goproxy would have discarded the request and sent the new response to the client.

In order to refuse connections to reddit at work time

    func(r *http.Request,ctx *goproxy.ProxyCtx)(*http.Request,*http.Response) {
        if h,_,_ := time.Now().Clock(); h >= 8 && h <= 17 {
            return r,goproxy.NewResponse(r,
                    "Don't waste your time!")
        return r,nil

DstHostIs returns a ReqCondition, that is a function receiving a Request and returning a boolean we will only process requests that matches the condition. DstHostIs("") will return a ReqCondition accepting only requests directed to "".

DoFunc will recieve a function that will preprocess the request. We can change the request, or return a response. If the time is between 8:00am and 17:00pm, we will neglect the request, and return a precanned text response saying "do not waste your time".

See additional examples in the examples directory.

What's New

  1. Ability to Hijack CONNECT requests. See the eavesdropper example
    1. Transparent proxy support for http/https including MITM certificate generation for TLS. See the transparent example.


I put the software temporarily under the Go-compatible BSD license, if this prevents someone from using the software, do let mee know and I'll consider changing it.

At any rate, user feedback is very important for me, so I'll be delighted to know if you're using this package.

Beta Software

I've received a positive feedback from a few people who use goproxy in production settings. I believe it is good enough for usage.

I'll try to keep reasonable backwards compatability. In case of a major API change, I'll change the import path.

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