⚡ Fast • 🪶 Lightweight • 0️⃣ Dependency • 🔌 Pluggable • 😈 TLS interception • 🔒 DNS-over-HTTPS • 🔥 Poor Man's VPN • ⏪ Reverse & ⏩ Forward • 👮🏿 "Proxy Server" framework • 🌐 "Web Server" framework • ➵ ➶ ➷ ➠ "PubSub" framework • 👷 "Work" acceptor & executor framework
[](https://pypi.org/project/proxy.py/) [](https://hub.docker.com/r/abhinavsingh/proxy.py) [](https://github.com/abhinavsingh/proxy.py) [](https://gitter.im/proxy-py/community) [](https://github.com/abhinavsingh/proxy.py/blob/develop/LICENSE) [](https://abhinavsingh.com/proxy-py-a-lightweight-single-file-http-proxy-server-in-python/) [](https://abhinavsingh.com/proxy-py-a-lightweight-single-file-http-proxy-server-in-python/) [](https://abhinavsingh.com/proxy-py-a-lightweight-single-file-http-proxy-server-in-python/) [](https://github.com/abhinavsingh/proxy.py/actions/workflows/test-library.yml) [](https://github.com/abhinavsingh/proxy.py/actions/workflows/test-docker.yml) [](https://github.com/abhinavsingh/proxy.py/actions/workflows/test-dashboard.yml) [](https://github.com/abhinavsingh/proxy.py/actions/workflows/test-brew.yml) [](https://github.com/abhinavsingh/proxy.py/actions/workflows/codeql-analysis.yml) [](https://github.com/abhinavsingh/proxy.py/issues) [](https://twitter.com/imoracle) [](https://github.com/jaxl-innovations-private-limited) [](https://pypi.org/project/proxy.py/) [](https://www.python.org/) [](http://mypy-lang.org/) [](https://codecov.io/gh/abhinavsingh/proxy.py) # Table of Contents - [Features](#features) - [Install](#install) - [Stable vs Develop](#stable-vs-develop) - [Using PIP](#using-pip) - [Stable version](#stable-version-with-pip) - [Development version](#development-version-with-pip) - [Using Docker](#using-docker) - [Stable version](#stable-version-from-docker-hub) - [Development version](#build-development-version-locally) - [Using HomeBrew](#using-homebrew) - [Stable version](#stable-version-with-homebrew) - [Development version](#development-version-with-homebrew) - [Start proxy.py](#start-proxypy) - [From command line when installed using PIP](#from-command-line-when-installed-using-pip) - [Run it](#run-it) - [Understanding logs](#understanding-logs) - [Enable DEBUG logging](#enable-debug-logging) - [From command line using repo source](#from-command-line-using-repo-source) - [Docker Image](#docker-image) - [Customize Startup Flags](#customize-startup-flags) - [Plugin Examples](#plugin-examples) - [HTTP Proxy Plugins](#http-proxy-plugins) - [ShortLink Plugin](#shortlinkplugin) - [Modify Post Data Plugin](#modifypostdataplugin) - [Mock Api Plugin](#mockrestapiplugin) - [Redirect To Custom Server Plugin](#redirecttocustomserverplugin) - [Filter By Upstream Host Plugin](#filterbyupstreamhostplugin) - [Cache Responses Plugin](#cacheresponsesplugin) - [Man-In-The-Middle Plugin](#maninthemiddleplugin) - [Proxy Pool Plugin](#proxypoolplugin) - [FilterByClientIpPlugin](#filterbyclientipplugin) - [ModifyChunkResponsePlugin](#modifychunkresponseplugin) - [CloudflareDnsResolverPlugin](#cloudflarednsresolverplugin) - [CustomDnsResolverPlugin](#customdnsresolverplugin) - [CustomNetworkInterface](#customnetworkinterface) - [HTTP Web Server Plugins](#http-web-server-plugins) - [Reverse Proxy](#reverse-proxy) - [Web Server Route](#web-server-route) - [Plugin Ordering](#plugin-ordering) - [End-to-End Encryption](#end-to-end-encryption) - [TLS Interception](#tls-interception) - [TLS Interception With Docker](#tls-interception-with-docker) - [Proxy Over SSH Tunnel](#proxy-over-ssh-tunnel) - [Proxy Remote Requests Locally](#proxy-remote-requests-locally) - [Proxy Local Requests Remotely](#proxy-local-requests-remotely) - [Embed proxy.py](#embed-proxypy) - [Blocking Mode](#blocking-mode) - [Non-blocking Mode](#non-blocking-mode) - [Ephemeral Port](#ephemeral-port) - [Loading Plugins](#loading-plugins) - [Unit testing with proxy.py](#unit-testing-with-proxypy) - [proxy.TestCase](#proxytestcase) - [Override Startup Flags](#override-startup-flags) - [With unittest.TestCase](#with-unittesttestcase) - [Utilities](#utilities) - [TCP](#tcp-sockets) - [new_socket_connection](#new_socket_connection) - [socket_connection](#socket_connection) - [Http](#http-client) - [build_http_request](#build_http_request) - [build_http_response](#build_http_response) - [Public Key Infrastructure](#pki) - [API Usage](#api-usage) - [CLI Usage](#cli-usage) - [Run Dashboard](#run-dashboard) - [Inspect Traffic](#inspect-traffic) - [Chrome DevTools Protocol](#chrome-devtools-protocol) - [Frequently Asked Questions](#frequently-asked-questions) - [Threads vs Threadless](#threads-vs-threadless) - [SyntaxError: invalid syntax](#syntaxerror-invalid-syntax) - [Unable to load plugins](#unable-to-load-plugins) - [Unable to connect with proxy.py from remote host](#unable-to-connect-with-proxypy-from-remote-host) - [Basic auth not working with a browser](#basic-auth-not-working-with-a-browser) - [Docker image not working on MacOS](#docker-image-not-working-on-macos) - [ValueError: filedescriptor out of range in select](#valueerror-filedescriptor-out-of-range-in-select) - [None:None in access logs](#nonenone-in-access-logs) - [OSError when wrapping client for TLS Interception](#oserror-when-wrapping-client-for-tls-interception) - [Plugin Developer and Contributor Guide](#plugin-developer-and-contributor-guide) - [High level architecture](#high-level-architecture) - [Everything is a plugin](#everything-is-a-plugin) - [Internal Documentation](#internal-documentation) - [Development Guide](#development-guide) - [Setup Local Environment](#setup-local-environment) - [Setup Git Hooks](#setup-git-hooks) - [Sending a Pull Request](#sending-a-pull-request) - [Flags](#flags) - [Changelog](#changelog) - [v2.x](#v2x) - [v1.x](#v1x) - [v0.x](#v0x) # Features - Fast & Scalable - Scales by using all available cores on the system - Threadless executions using asyncio - Made to handle `tens-of-thousands` connections / sec ```console # On Macbook Pro 2019 / 2.4 GHz 8-Core Intel Core i9 / 32 GB RAM ❯ hey -n 10000 -c 100 http://localhost:8899/http-route-example Summary: Total: 0.3248 secs Slowest: 0.1007 secs Fastest: 0.0002 secs Average: 0.0028 secs Requests/sec: 30784.7958 Total data: 190000 bytes Size/request: 19 bytes Response time histogram: 0.000 [1] | 0.010 [9533] |■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■■ 0.020 [384] |■■ Latency distribution: 10% in 0.0004 secs 25% in 0.0007 secs 50% in 0.0013 secs 75% in 0.0029 secs 90% in 0.0057 secs 95% in 0.0097 secs 99% in 0.0185 secs Status code distribution: [200] 10000 responses ``` - Lightweight - Uses only `~5-20MB` RAM - No external dependency other than standard Python library - Programmable - Customize proxy behavior using [Proxy Server Plugins](#http-proxy-plugins). Example: - `--plugins proxy.plugin.ProxyPoolPlugin` - Optionally, enable builtin [Web Server Plugins](#http-web-server-plugins). Example: - `--plugins proxy.plugin.ReverseProxyPlugin` - Plugin API is currently in development phase, expect breaking changes - Realtime Dashboard - Optionally, enable [proxy.py dashboard](#run-dashboard). - Available at `http://localhost:8899/dashboard`. - [Inspect, Monitor, Control and Configure](#inspect-traffic) `proxy.py` at runtime - [Chrome DevTools Protocol](#chrome-devtools-protocol) support - Extend dashboard using plugins - Dashboard is currently in development phase, expect breaking changes - Secure - Enable end-to-end encryption between clients and `proxy.py` - See [End-to-End Encryption](#end-to-end-encryption) - Private - Everyone deserves privacy. Browse with malware and adult content protection - See [DNS-over-HTTPS](#cloudflarednsresolverplugin) - Man-In-The-Middle - Can decrypt TLS traffic between clients and upstream servers - See [TLS Interception](#tls-interception) - Supported proxy protocols - `http(s)` - `http1` - `http1.1` with pipeline - `http2` - `websockets` - Static file server support - See `--enable-static-server` and `--static-server-dir` flags - Optimized for large file uploads and downloads - See `--client-recvbuf-size` and `--server-recvbuf-size` flag - `IPv4` and `IPv6` support - See `--hostname` flag - Unix domain socket support - See `--unix-socket-path` flag - Basic authentication support - See `--basic-auth` flag - PAC (Proxy Auto-configuration) support - See `--pac-file` and `--pac-file-url-path` flags # Install ## Stable vs Develop `master` branch contains latest stable code and is available via `PyPi` repository `develop` branch contains cutting edge changes Development branch is kept stable *(most of the times)*. But if you want 100% reliability and serving users in production environment, always use stable version from `PyPi` or `Docker` container from `hub.docker.com`. ## Using PIP ### Stable Version with PIP Install from `PyPi` ```console ❯ pip install --upgrade proxy.py ``` or from GitHub `master` branch ```console ❯ pip install git+https://github.com/abhinavsingh/proxy.py.git@master ``` ### Development Version with PIP ```console ❯ pip install git+https://github.com/abhinavsingh/proxy.py.git@develop ``` ## Using Docker ### Stable Version from Docker Hub ```console ❯ docker run -it -p 8899:8899 --rm abhinavsingh/proxy.py:latest ``` ### Build Development Version Locally ```console ❯ git clone https://github.com/abhinavsingh/proxy.py.git ❯ cd proxy.py && make container ❯ docker run -it -p 8899:8899 --rm abhinavsingh/proxy.py:latest ``` [](https://github.com/moby/vpnkit/issues/469) `docker` image is currently broken on `macOS` due to incompatibility with [vpnkit](https://github.com/moby/vpnkit/issues/469). ## Using HomeBrew ### Stable Version with HomeBrew ```console ❯ brew install https://raw.githubusercontent.com/abhinavsingh/proxy.py/develop/helper/homebrew/stable/proxy.rb ``` ### Development Version with HomeBrew ```console ❯ brew install https://raw.githubusercontent.com/abhinavsingh/proxy.py/develop/helper/homebrew/develop/proxy.rb ``` # Start proxy.py ## From command line when installed using PIP When `proxy.py` is installed using `pip`, an executable named `proxy` is placed under your `$PATH`. ### Run it Simply type `proxy` on command line to start with default configuration. ```console ❯ proxy ...[redacted]... - Loaded plugin proxy.http.proxy.HttpProxyPlugin ...[redacted]... - Started 8 threadless workers ...[redacted]... - Started 8 acceptors ...[redacted]... - Listening on 127.0.0.1:8899 ``` ### Understanding logs Things to notice from above logs: - `Loaded plugin` - `proxy.py` will load `proxy.http.proxy.HttpProxyPlugin` by default - As name suggests, this core plugin adds `http(s)` proxy server capabilities to `proxy.py` instance - `Started N threadless workers` - By default, `proxy.py` will start as many worker processes as there are CPU cores on the machine - Use `--num-workers` flag to customize number of worker processes - See [Threads vs Threadless](#threads-vs-threadless) to understand how to control execution mode - `Started N acceptors` - By default, `proxy.py` will start as many acceptor processes as there are CPU cores on the machine - Use `--num-acceptors` flag to customize number of acceptor processes - See [High Level Architecture](#high-level-architecture) to understand relationship between acceptors and workers - `Started server on ::1:8899` - By default, `proxy.py` listens on IPv6 `::1`, which is equivalent of IPv4 `127.0.0.1` - If you want to access `proxy.py` from external host, use `--hostname ::` or `--hostname 0.0.0.0` or bind to any other interface available on your machine. - See [CustomNetworkInterface](#customnetworkinterface) for how to customize `proxy.py` *public IP seen by upstream servers*. - `Port 8899` - Use `--port` flag to customize default TCP port. ### Enable DEBUG logging All the logs above are `INFO` level logs, default `--log-level` for `proxy.py` Lets start `proxy.py` with `DEBUG` level logging: ```console ❯ proxy --log-level d ...[redacted]... - Open file descriptor soft limit set to 1024 ...[redacted]... - Loaded plugin proxy.http_proxy.HttpProxyPlugin ...[redacted]... - Started 8 workers ...[redacted]... - Started server on ::1:8899 ``` You can use single letter to customize log level. Example: - `d = DEBUG` - `i = INFO` - `w = WARNING` - `e = ERROR` - `c = CRITICAL` As we can see from the above logs, before starting up: - `proxy.py` tried to set open file limit `ulimit` on the system - Default value for `--open-file-limit` used is `1024` - `--open-file-limit` flag is a no-op on `Windows` operating systems See [flags](#flags) for full list of available configuration options. ## From command line using repo source If you are trying to run `proxy.py` from source code, there is no binary file named `proxy` in the source code. To start `proxy.py` from source code follow these instructions: - Clone repo ```console ❯ git clone https://github.com/abhinavsingh/proxy.py.git ❯ cd proxy.py ``` - Create a Python 3 virtual env ```console ❯ python3 -m venv venv ❯ source venv/bin/activate ``` - Install deps ```console ❯ make lib-dep ``` - Optionally, run tests ```console ❯ make ``` - Run `proxy.py` ```console ❯ python -m proxy ``` See [Plugin Developer and Contributor Guide](#plugin-developer-and-contributor-guide) if you plan to work with `proxy.py` source code. ## Docker image ### Customize startup flags By default `docker` binary is started with IPv4 networking flags: --hostname 0.0.0.0 --port 8899 You can override flag from command line when starting the docker container. For example, to check `proxy.py` version within the docker container, run: ❯ docker run -it \ -p 8899:8899 \ --rm abhinavsingh/proxy.py:latest \ -v # Plugin Examples - See [plugin](https://github.com/abhinavsingh/proxy.py/tree/develop/proxy/plugin) module for full code. - All the bundled plugin examples also works with `https` traffic - Require additional flags and certificate generation - See [TLS Interception](#tls-interception). - Plugin examples are also bundled with Docker image. - See [Customize startup flags](#customize-startup-flags) to try plugins with Docker image. ## HTTP Proxy Plugins ### ShortLinkPlugin Add support for short links in your favorite browsers / applications. [](https://github.com/abhinavsingh/proxy.py#shortlinkplugin) Start `proxy.py` as: ```console ❯ proxy \ --plugins proxy.plugin.ShortLinkPlugin ``` Now you can speed up your daily browsing experience by visiting your favorite website using single character domain names :). This works across all browsers. Following short links are enabled by default: | Short Link | Destination URL | | :--------: | :--------------: | | a/ | amazon.com | | i/ | instagram.com | | l/ | linkedin.com | | f/ | facebook.com | | g/ | google.com | | t/ | twitter.com | | w/ | web.whatsapp.com | | y/ | youtube.com | | proxy/ | localhost:8899 | ### ModifyPostDataPlugin Modifies POST request body before sending request to upstream server. Start `proxy.py` as: ```console ❯ proxy \ --plugins proxy.plugin.ModifyPostDataPlugin ``` By default plugin replaces POST body content with hardcoded `b'{"key": "modified"}'` and enforced `Content-Type: application/json`. Verify the same using `curl -x localhost:8899 -d '{"key": "value"}' http://httpbin.org/post` ```console { "args": {}, "data": "{\"key\": \"modified\"}", "files": {}, "form": {}, "headers": { "Accept": "*/*", "Content-Length": "19", "Content-Type": "application/json", "Host": "httpbin.org", "User-Agent": "curl/7.54.0" }, "json": { "key": "modified" }, "origin": "1.2.3.4, 5.6.7.8", "url": "https://httpbin.org/post" } ``` Note following from the response above: 1. POST data was modified `"data": "{\"key\": \"modified\"}"`. Original `curl` command data was `{"key": "value"}`. 2. Our `curl` command did not add any `Content-Type` header, but our plugin did add one `"Content-Type": "application/json"`. Same can also be verified by looking at `json` field in the output above: ``` "json": { "key": "modified" }, ``` 3. Our plugin also added a `Content-Length` header to match length of modified body. ### MockRestApiPlugin Mock responses for your server REST API. Use to test and develop client side applications without need of an actual upstream REST API server. Start `proxy.py` as: ```console ❯ proxy \ --plugins proxy.plugin.ProposedRestApiPlugin ``` Verify mock API response using `curl -x localhost:8899 http://api.example.com/v1/users/` ```console {"count": 2, "next": null, "previous": null, "results": [{"email": "you@example.com", "groups": [], "url": "api.example.com/v1/users/1/", "username": "admin"}, {"email": "someone@example.com", "groups": [], "url": "api.example.com/v1/users/2/", "username": "admin"}]} ``` Verify the same by inspecting `proxy.py` logs: ```console 2019-09-27 12:44:02,212 - INFO - pid:7077 - access_log:1210 - ::1:64792 - GET None:None/v1/users/ - None None - 0 byte ``` Access log shows `None:None` as server `ip:port`. `None` simply means that the server connection was never made, since response was returned by our plugin. Now modify `ProposedRestApiPlugin` to returns REST API mock responses as expected by your clients. ### RedirectToCustomServerPlugin Redirects all incoming `http` requests to custom web server. By default, it redirects client requests to inbuilt web server, also running on `8899` port. Start `proxy.py` and enable inbuilt web server: ```console ❯ proxy \ --enable-web-server \ --plugins proxy.plugin.RedirectToCustomServerPlugin ``` Verify using `curl -v -x localhost:8899 http://google.com` ``` ... [redacted] ... < HTTP/1.1 404 NOT FOUND < Server: proxy.py v1.0.0 < Connection: Close < * Closing connection 0 ``` Above `404` response was returned from `proxy.py` web server. Verify the same by inspecting the logs for `proxy.py`. Along with the proxy request log, you must also see a http web server request log. ``` 2019-09-24 19:09:33,602 - INFO - pid:49996 - access_log:1241 - ::1:49525 - GET / 2019-09-24 19:09:33,603 - INFO - pid:49995 - access_log:1157 - ::1:49524 - GET localhost:8899/ - 404 NOT FOUND - 70 bytes ``` ### FilterByUpstreamHostPlugin Drops traffic by inspecting upstream host. By default, plugin drops traffic for `facebook.com` and `www.facebok.com`. Start `proxy.py` as: ```console ❯ proxy \ --plugins proxy.plugin.FilterByUpstreamHostPlugin ``` Verify using `curl -v -x localhost:8899 http://facebook.com`: ```console ... [redacted] ... < HTTP/1.1 418 I'm a tea pot < Proxy-agent: proxy.py v1.0.0 * no chunk, no close, no size. Assume close to signal end < * Closing connection 0 ``` Above `418 I'm a tea pot` is sent by our plugin. Verify the same by inspecting logs for `proxy.py`: ```console 2019-09-24 19:21:37,893 - ERROR - pid:50074 - handle_readables:1347 - HttpProtocolException type raised Traceback (most recent call last): ... [redacted] ... 2019-09-24 19:21:37,897 - INFO - pid:50074 - access_log:1157 - ::1:49911 - GET None:None/ - None None - 0 bytes ``` ### CacheResponsesPlugin Caches Upstream Server Responses. Start `proxy.py` as: ```console ❯ proxy \ --plugins proxy.plugin.CacheResponsesPlugin ``` Verify using `curl -v -x localhost:8899 http://httpbin.org/get`: ```console ... [redacted] ... < HTTP/1.1 200 OK < Access-Control-Allow-Credentials: true < Access-Control-Allow-Origin: * < Content-Type: application/json < Date: Wed, 25 Sep 2019 02:24:25 GMT < Referrer-Policy: no-referrer-when-downgrade < Server: nginx < X-Content-Type-Options: nosniff < X-Frame-Options: DENY < X-XSS-Protection: 1; mode=block < Content-Length: 202 < Connection: keep-alive < { "args": {}, "headers": { "Accept": "*/*", "Host": "httpbin.org", "User-Agent": "curl/7.54.0" }, "origin": "1.2.3.4, 5.6.7.8", "url": "https://httpbin.org/get" } * Connection #0 to host localhost left intact ``` Get path to the cache file from `proxy.py` logs: ```console ... [redacted] ... - GET httpbin.org:80/get - 200 OK - 556 bytes ... [redacted] ... - Cached response at /var/folders/k9/x93q0_xn1ls9zy76m2mf2k_00000gn/T/httpbin.org-1569378301.407512.txt ``` Verify contents of the cache file `cat /path/to/your/cache/httpbin.org.txt` ```console HTTP/1.1 200 OK Access-Control-Allow-Credentials: true Access-Control-Allow-Origin: * Content-Type: application/json Date: Wed, 25 Sep 2019 02:24:25 GMT Referrer-Policy: no-referrer-when-downgrade Server: nginx X-Content-Type-Options: nosniff X-Frame-Options: DENY X-XSS-Protection: 1; mode=block Content-Length: 202 Connection: keep-alive { "args": {}, "headers": { "Accept": "*/*", "Host": "httpbin.org", "User-Agent": "curl/7.54.0" }, "origin": "1.2.3.4, 5.6.7.8", "url": "https://httpbin.org/get" } ``` ### ManInTheMiddlePlugin Modifies upstream server responses. Start `proxy.py` as: ```console ❯ proxy \ --plugins proxy.plugin.ManInTheMiddlePlugin ``` Verify using `curl -v -x localhost:8899 http://google.com`: ```console ... [redacted] ... < HTTP/1.1 200 OK < Content-Length: 28 < * Connection #0 to host localhost left intact Hello from man in the middle ``` Response body `Hello from man in the middle` is sent by our plugin. ### ProxyPoolPlugin Forward incoming proxy requests to a set of upstream proxy servers. Let's start upstream proxies first. Start `proxy.py` on port `9000` and `9001` ```console ❯ proxy --port 9000 ``` ```console ❯ proxy --port 9001 ``` Now, start `proxy.py` with `ProxyPoolPlugin` (on default `8899` port), pointing to our upstream proxies at `9000` and `9001` port. ```console ❯ proxy \ --plugins proxy.plugin.ProxyPoolPlugin \ --proxy-pool localhost:9000 \ --proxy-pool localhost:9001 ``` Make a curl request via `8899` proxy: `curl -v -x localhost:8899 http://httpbin.org/get` Verify that `8899` proxy forwards requests to upstream proxies by checking respective logs. ### FilterByClientIpPlugin Reject traffic from specific IP addresses. By default this plugin blocks traffic from `127.0.0.1` and `::1`. Start `proxy.py` as: ```console ❯ proxy \ --plugins proxy.plugin.FilterByClientIpPlugin ``` Send a request using `curl -v -x localhost:8899 http://google.com`: ```console ... [redacted] ... > Proxy-Connection: Keep-Alive > < HTTP/1.1 418 I'm a tea pot < Connection: close < * Closing connection 0 ``` Modify plugin to your taste e.g. Allow specific IP addresses only. ### ModifyChunkResponsePlugin This plugin demonstrate how to modify chunked encoded responses. In able to do so, this plugin uses `proxy.py` core to parse the chunked encoded response. Then we reconstruct the response using custom hardcoded chunks, ignoring original chunks received from upstream server. Start `proxy.py` as: ```console ❯ proxy \ --plugins proxy.plugin.ModifyChunkResponsePlugin ``` Verify using `curl -v -x localhost:8899 http://httpbin.org/stream/5`: ```console ... [redacted] ... modify chunk response plugin * Connection #0 to host localhost left intact * Closing connection 0 ``` Modify `ModifyChunkResponsePlugin` to your taste. Example, instead of sending hardcoded chunks, parse and modify the original `JSON` chunks received from the upstream server. ### CloudflareDnsResolverPlugin This plugin uses `Cloudflare` hosted `DNS-over-HTTPS` [API](https://developers.cloudflare.com/1.1.1.1/encrypted-dns/dns-over-https/make-api-requests/dns-json) (json). `DoH` mandates a HTTP2 compliant client. Unfortunately `proxy.py` doesn't provide that yet, so we use a dependency. Install it: ```console ❯ pip install "httpx[http2]" ``` Now start `proxy.py` as: ```console ❯ proxy \ --plugins proxy.plugin.CloudflareDnsResolverPlugin ``` By default, `CloudflareDnsResolverPlugin` runs in `security` mode and provides malware protection. Use `--cloudflare-dns-mode family` to also enable adult content protection too. ### CustomDnsResolverPlugin This plugin demonstrate how to use a custom DNS resolution implementation with `proxy.py`. This example plugin currently uses Python's in-built resolution mechanism. Customize code to your taste. Example, query your custom DNS server, implement DoH or other mechanisms. Start `proxy.py` as: ```console ❯ proxy \ --plugins proxy.plugin.CustomDnsResolverPlugin ``` ### CustomNetworkInterface `HttpProxyBasePlugin.resolve_dns` callback can also be used to configure `network interface` which must be used as the `source_address` for connection to the upstream server. See [this thread](https://github.com/abhinavsingh/proxy.py/issues/535#issuecomment-961510862) for more details. PS: There is no plugin named, but [CustomDnsResolverPlugin](#customdnsresolverplugin) can be easily customized according to your needs. ## HTTP Web Server Plugins ### Reverse Proxy Extend in-built Web Server to add Reverse Proxy capabilities. Start `proxy.py` as: ```console ❯ proxy --enable-web-server \ --plugins proxy.plugin.ReverseProxyPlugin ``` With default configuration, `ReverseProxyPlugin` plugin is equivalent to following `Nginx` config: ```console location /get { proxy_pass http://httpbin.org/get } ``` Verify using `curl -v localhost:8899/get`: ```console { "args": {}, "headers": { "Accept": "*/*", "Host": "localhost", "User-Agent": "curl/7.64.1" }, "origin": "1.2.3.4, 5.6.7.8", "url": "https://localhost/get" } ``` ### Web Server Route Demonstrates inbuilt web server routing using plugin. Start `proxy.py` as: ```console ❯ proxy --enable-web-server \ --plugins proxy.plugin.WebServerPlugin ``` Verify using `curl -v localhost:8899/http-route-example`, should return: ```console HTTP route response ``` ## Plugin Ordering When using multiple plugins, depending upon plugin functionality, it might be worth considering the order in which plugins are passed on the command line. Plugins are called in the same order as they are passed. Example, say we are using both `FilterByUpstreamHostPlugin` and `RedirectToCustomServerPlugin`. Idea is to drop all incoming `http` requests for `facebook.com` and `www.facebook.com` and redirect other `http` requests to our inbuilt web server. Hence, in this scenario it is important to use `FilterByUpstreamHostPlugin` before `RedirectToCustomServerPlugin`. If we enable `RedirectToCustomServerPlugin` before `FilterByUpstreamHostPlugin`, `facebook` requests will also get redirected to inbuilt web server, instead of being dropped. # End-to-End Encryption By default, `proxy.py` uses `http` protocol for communication with clients e.g. `curl`, `browser`. For enabling end-to-end encrypting using `tls` / `https` first generate certificates. **Checkout** the repository and run: ```console make https-certificates ``` Start `proxy.py` as: ```console ❯ proxy \ --cert-file https-cert.pem \ --key-file https-key.pem ``` Verify using `curl -x https://localhost:8899 --proxy-cacert https-cert.pem https://httpbin.org/get`: ```console { "args": {}, "headers": { "Accept": "*/*", "Host": "httpbin.org", "User-Agent": "curl/7.54.0" }, "origin": "1.2.3.4, 5.6.7.8", "url": "https://httpbin.org/get" } ``` If you want to avoid passing `--proxy-cacert` flag, also consider signing generated SSL certificates. Example: First, generate CA certificates: ```console make ca-certificates ``` Then, sign SSL certificate: ```console make sign-https-certificates ``` Now restart the server with `--cert-file https-signed-cert.pem` flag. Note that you must also trust generated `ca-cert.pem` in your system keychain. # TLS Interception By default, `proxy.py` will not decrypt `https` traffic between client and server. To enable TLS interception first generate root CA certificates: ```console ❯ make ca-certificates ``` Lets also enable `CacheResponsePlugin` so that we can verify decrypted response from the server. Start `proxy.py` as: ```console ❯ proxy \ --plugins proxy.plugin.CacheResponsesPlugin \ --ca-key-file ca-key.pem \ --ca-cert-file ca-cert.pem \ --ca-signing-key-file ca-signing-key.pem ``` [](https://github.com/abhinavsingh/proxy.py#flags) Also provide explicit CA bundle path needed for validation of peer certificates. See `--ca-file` flag. Verify TLS interception using `curl` ```console ❯ curl -v -x localhost:8899 --cacert ca-cert.pem https://httpbin.org/get ``` ```console * issuer: C=US; ST=CA; L=SanFrancisco; O=proxy.py; OU=CA; CN=Proxy PY CA; emailAddress=proxyca@mailserver.com * SSL certificate verify ok. > GET /get HTTP/1.1 ... [redacted] ... < Connection: keep-alive < { "args": {}, "headers": { "Accept": "*/*", "Host": "httpbin.org", "User-Agent": "curl/7.54.0" }, "origin": "1.2.3.4, 5.6.7.8", "url": "https://httpbin.org/get" } ``` The `issuer` line confirms that response was intercepted. Also verify the contents of cached response file. Get path to the cache file from `proxy.py` logs. `❯ cat /path/to/your/tmp/directory/httpbin.org-1569452863.924174.txt` ```console HTTP/1.1 200 OK Access-Control-Allow-Credentials: true Access-Control-Allow-Origin: * Content-Type: application/json Date: Wed, 25 Sep 2019 23:07:05 GMT Referrer-Policy: no-referrer-when-downgrade Server: nginx X-Content-Type-Options: nosniff X-Frame-Options: DENY X-XSS-Protection: 1; mode=block Content-Length: 202 Connection: keep-alive { "args": {}, "headers": { "Accept": "*/*", "Host": "httpbin.org", "User-Agent": "curl/7.54.0" }, "origin": "1.2.3.4, 5.6.7.8", "url": "https://httpbin.org/get" } ``` Viola!!! If you remove CA flags, encrypted data will be found in the cached file instead of plain text. Now use CA flags with other [plugin examples](#plugin-examples) to see them work with `https` traffic. ## TLS Interception With Docker Important notes about TLS Interception with Docker container: - Since `v2.2.0`, `proxy.py` docker container also ships with `openssl`. This allows `proxy.py` to generate certificates on the fly for TLS Interception. - For security reasons, `proxy.py` docker container doesn't ship with CA certificates. Here is how to start a `proxy.py` docker container with TLS Interception: 1. Generate CA certificates on host computer ```console ❯ make ca-certificates ``` 2. Copy all generated certificates into a separate directory. We'll later mount this directory into our docker container ```console ❯ mkdir /tmp/ca-certificates ❯ cp ca-cert.pem ca-key.pem ca-signing-key.pem /tmp/ca-certificates ``` 3. Start docker container ```console ❯ docker run -it --rm \ -v /tmp/ca-certificates:/tmp/ca-certificates \ -p 8899:8899 \ abhinavsingh/proxy.py:latest \ --hostname 0.0.0.0 \ --plugins proxy.plugin.CacheResponsesPlugin \ --ca-key-file /tmp/ca-certificates/ca-key.pem \ --ca-cert-file /tmp/ca-certificates/ca-cert.pem \ --ca-signing-key /tmp/ca-certificates/ca-signing-key.pem ``` - `-v /tmp/ca-certificates:/tmp/ca-certificates` flag mounts our CA certificate directory in container environment - `--plugins proxy.plugin.CacheResponsesPlugin` enables `CacheResponsesPlugin` so that we can inspect intercepted traffic - `--ca-*` flags enable TLS Interception. 4. From another terminal, try TLS Interception using `curl`. You can omit `--cacert` flag if CA certificate is already trusted by the system. ```console ❯ curl -v \ --cacert ca-cert.pem \ -x 127.0.0.1:8899 \ https://httpbin.org/get ``` 5. Verify `issuer` field from response headers. ```console * Server certificate: * subject: CN=httpbin.org; C=NA; ST=Unavailable; L=Unavailable; O=Unavailable; OU=Unavailable * start date: Jun 17 09:26:57 2020 GMT * expire date: Jun 17 09:26:57 2022 GMT * subjectAltName: host "httpbin.org" matched cert's "httpbin.org" * issuer: CN=example.com * SSL certificate verify ok. ``` 6. Back on docker terminal, copy response dump path logs. ```console ...[redacted]... [I] access_log:338 - 172.17.0.1:56498 - CONNECT httpbin.org:443 - 1031 bytes - 1216.70 ms ...[redacted]... [I] close:49 - Cached response at /tmp/httpbin.org-ae1a927d064e4ab386ea319eb38fe251.txt ``` 7. In another terminal, `cat` the response dump: ```console ❯ docker exec -it $(docker ps | grep proxy.py | awk '{ print $1 }') cat /tmp/httpbin.org-ae1a927d064e4ab386ea319eb38fe251.txt HTTP/1.1 200 OK ...[redacted]... { ...[redacted]..., "url": "http://httpbin.org/get" } ``` # Proxy Over SSH Tunnel **This is a WIP and may not work as documented** Requires `paramiko` to work. See [requirements-tunnel.txt](https://github.com/abhinavsingh/proxy.py/blob/develop/requirements-tunnel.txt) ## Proxy Remote Requests Locally | +------------+ | +----------+ | LOCAL | | | REMOTE | | HOST | <== SSH ==== :8900 == | SERVER | +------------+ | +----------+ :8899 proxy.py | | FIREWALL (allow tcp/22) ## What Proxy HTTP(s) requests made on a `remote` server through `proxy.py` server running on `localhost`. ### How - Requested `remote` port is forwarded over the SSH connection. - `proxy.py` running on the `localhost` handles and responds to `remote` proxy requests. ### Requirements 1. `localhost` MUST have SSH access to the `remote` server 2. `remote` server MUST be configured to proxy HTTP(s) requests through the forwarded port number e.g. `:8900`. - `remote` and `localhost` ports CAN be same e.g. `:8899`. - `:8900` is chosen in ascii art for differentiation purposes. ### Try it Start `proxy.py` as: ```console ❯ # On localhost ❯ proxy --enable-tunnel \ --tunnel-username username \ --tunnel-hostname ip.address.or.domain.name \ --tunnel-port 22 \ --tunnel-remote-host 127.0.0.1 --tunnel-remote-port 8899 ``` Make a HTTP proxy request on `remote` server and verify that response contains public IP address of `localhost` as origin: ```console ❯ # On remote ❯ curl -x 127.0.0.1:8899 http://httpbin.org/get { "args": {}, "headers": { "Accept": "*/*", "Host": "httpbin.org", "User-Agent": "curl/7.54.0" }, "origin": "x.x.x.x, y.y.y.y", "url": "https://httpbin.org/get" } ``` Also, verify that `proxy.py` logs on `localhost` contains `remote` IP as client IP. ```console access_log:328 - remote:52067 - GET httpbin.org:80 ``` ## Proxy Local Requests Remotely | +------------+ | +----------+ | LOCAL | | | REMOTE | | HOST | === SSH =====> | SERVER | +------------+ | +----------+ | :8899 proxy.py | FIREWALL (allow tcp/22) # Embed proxy.py ## Blocking Mode Start `proxy.py` in embedded mode with default configuration by using `proxy.main` method. Example: ```python import proxy if __name__ == '__main__': proxy.main() ``` Customize startup flags by passing list of input arguments: ```python import proxy if __name__ == '__main__': proxy.main([ '--hostname', '::1', '--port', '8899' ]) ``` or, customize startup flags by passing them as kwargs: ```python import ipaddress import proxy if __name__ == '__main__': proxy.main( hostname=ipaddress.IPv6Address('::1'), port=8899 ) ``` Note that: 1. Calling `main` is simply equivalent to starting `proxy.py` from command line. 2. `main` will block until `proxy.py` shuts down. ## Non-blocking Mode Start `proxy.py` in non-blocking embedded mode with default configuration by using `Proxy` context manager: Example: ```python import proxy if __name__ == '__main__': with proxy.Proxy([]) as p: # ... your logic here ... ``` Note that: 1. `Proxy` is similar to `main`, except `Proxy` does not block. 2. Internally `Proxy` is a context manager. 3. It will start `proxy.py` when called and will shut it down once the scope ends. 4. Just like `main`, startup flags with `Proxy` can be customized by either passing flags as list of input arguments e.g. `Proxy(['--port', '8899'])` or by using passing flags as kwargs e.g. `Proxy(port=8899)`. ## Ephemeral Port Use `--port=0` to bind `proxy.py` on a random port allocated by the kernel. In embedded mode, you can access this port. Example: ```python import proxy if __name__ == '__main__': with proxy.Proxy([]) as p: print(p.acceptors.flags.port) ``` `acceptors.flags.port` will give you access to the random port allocated by the kernel. ## Loading Plugins Users can use `--plugins` flag multiple times to load multiple plugins. See [Unable to load plugins](#unable-to-load-plugins) if you are running into issues. When using in embedded mode, you have a few more options. Example: 1. Provide a fully-qualified name of the plugin class as `bytes` to the `proxy.main` method or `proxy.Proxy` context manager. 2. Provide `type` instance of the plugin class. This is especially useful if you plan to define plugins at runtime. Example, load a single plugin using `--plugins` flag: ```python import proxy if __name__ == '__main__': proxy.main([ '--plugins', 'proxy.plugin.CacheResponsesPlugin', ]) ``` For simplicity, you can also pass the list of plugins as a keyword argument to `proxy.main` or the `Proxy` constructor. Example: ```python import proxy from proxy.plugin import FilterByUpstreamHostPlugin if __name__ == '__main__': proxy.main([], plugins=[ b'proxy.plugin.CacheResponsesPlugin', FilterByUpstreamHostPlugin, ]) ``` # Unit testing with proxy.py ## proxy.TestCase To setup and teardown `proxy.py` for your Python `unittest` classes, simply use `proxy.TestCase` instead of `unittest.TestCase`. Example: ```python import proxy class TestProxyPyEmbedded(proxy.TestCase): def test_my_application_with_proxy(self) -> None: self.assertTrue(True) ``` Note that: 1. `proxy.TestCase` overrides `unittest.TestCase.run()` method to setup and teardown `proxy.py`. 2. `proxy.py` server will listen on a random available port on the system. This random port is available as `self.PROXY.acceptors.flags.port` within your test cases. 3. Only a single acceptor and worker is started by default (`--num-workers 1 --num-acceptors 1`) for faster setup and teardown. 4. Most importantly, `proxy.TestCase` also ensures `proxy.py` server is up and running before proceeding with execution of tests. By default, `proxy.TestCase` will wait for `10 seconds` for `proxy.py` server to start, upon failure a `TimeoutError` exception will be raised. ## Override startup flags To override default startup flags, define a `PROXY_PY_STARTUP_FLAGS` variable in your test class. Example: ```python class TestProxyPyEmbedded(TestCase): PROXY_PY_STARTUP_FLAGS = [ '--num-workers', '2', '--num-acceptors', '1', '--enable-web-server', ] def test_my_application_with_proxy(self) -> None: self.assertTrue(True) ``` See [test_embed.py](https://github.com/abhinavsingh/proxy.py/blob/develop/tests/test_embed.py) for full working example. ## With unittest.TestCase If for some reasons you are unable to directly use `proxy.TestCase`, then simply override `unittest.TestCase.run` yourself to setup and teardown `proxy.py`. Example: ```python import unittest import proxy class TestProxyPyEmbedded(unittest.TestCase): def test_my_application_with_proxy(self) -> None: self.assertTrue(True) def run(self, result: Optional[unittest.TestResult] = None) -> Any: with proxy.start([ '--num-workers', '1', '--num-acceptors', '1', '--port', '... random port ...']): super().run(result) ``` or simply setup / teardown `proxy.py` within `setUpClass` and `teardownClass` class methods. # Utilities ## TCP Sockets ### new_socket_connection Attempts to create an IPv4 connection, then IPv6 and finally a dual stack connection to provided address. ```python >>> conn = new_socket_connection(('httpbin.org', 80)) >>> ...[ use connection ]... >>> conn.close() ``` ### socket_connection `socket_connection` is a convenient decorator + context manager around `new_socket_connection` which ensures `conn.close` is implicit. As a context manager: ```python >>> with socket_connection(('httpbin.org', 80)) as conn: >>> ... [ use connection ] ... ``` As a decorator: ```python >>> @socket_connection(('httpbin.org', 80)) >>> def my_api_call(conn, *args, **kwargs): >>> ... [ use connection ] ... ``` ## Http Client ### build_http_request - Generate HTTP GET request ```python >>> build_http_request(b'GET', b'/') b'GET / HTTP/1.1\r\n\r\n' ``` - Generate HTTP GET request with headers ```python >>> build_http_request(b'GET', b'/', headers={b'Connection': b'close'}) b'GET / HTTP/1.1\r\nConnection: close\r\n\r\n' ``` - Generate HTTP POST request with headers and body ```python >>> import json >>> build_http_request(b'POST', b'/form', headers={b'Content-type': b'application/json'}, body=proxy.bytes_(json.dumps({'email': 'hello@world.com'}))) b'POST /form HTTP/1.1\r\nContent-type: application/json\r\n\r\n{"email": "hello@world.com"}' ``` ### build_http_response ```python build_http_response( status_code: int, protocol_version: bytes = HTTP_1_1, reason: Optional[bytes] = None, headers: Optional[Dict[bytes, bytes]] = None, body: Optional[bytes] = None) -> bytes ``` ## PKI ### API Usage - gen_private_key ```python gen_private_key( key_path: str, password: str, bits: int = 2048, timeout: int = 10) -> bool ``` - gen_public_key ```python gen_public_key( public_key_path: str, private_key_path: str, private_key_password: str, subject: str, alt_subj_names: Optional[List[str]] = None, extended_key_usage: Optional[str] = None, validity_in_days: int = 365, timeout: int = 10) -> bool ``` - remove_passphrase ```python remove_passphrase( key_in_path: str, password: str, key_out_path: str, timeout: int = 10) -> bool ``` - gen_csr ```python gen_csr( csr_path: str, key_path: str, password: str, crt_path: str, timeout: int = 10) -> bool ``` - sign_csr ```python sign_csr( csr_path: str, crt_path: str, ca_key_path: str, ca_key_password: str, ca_crt_path: str, serial: str, alt_subj_names: Optional[List[str]] = None, extended_key_usage: Optional[str] = None, validity_in_days: int = 365, timeout: int = 10) -> bool ``` See [pki.py](https://github.com/abhinavsingh/proxy.py/blob/develop/proxy/common/pki.py) and [test_pki.py](https://github.com/abhinavsingh/proxy.py/blob/develop/tests/common/test_pki.py) for usage examples. ### CLI Usage Use `proxy.common.pki` module for: 1. Generation of public and private keys 2. Generating CSR requests 3. Signing CSR requests using custom CA. ```console python -m proxy.common.pki -h usage: pki.py [-h] [--password PASSWORD] [--private-key-path PRIVATE_KEY_PATH] [--public-key-path PUBLIC_KEY_PATH] [--subject SUBJECT] action proxy.py v2.2.0 : PKI Utility positional arguments: action Valid actions: remove_passphrase, gen_private_key, gen_public_key, gen_csr, sign_csr optional arguments: -h, --help show this help message and exit --password PASSWORD Password to use for encryption. Default: proxy.py --private-key-path PRIVATE_KEY_PATH Private key path --public-key-path PUBLIC_KEY_PATH Public key path --subject SUBJECT Subject to use for public key generation. Default: /CN=example.com ``` ## Internal Documentation Code is well documented. Browse through internal class hierarchy and documentation using `pydoc3` ```console ❯ pydoc3 proxy PACKAGE CONTENTS __main__ common (package) core (package) http (package) main FILE /Users/abhinav/Dev/proxy.py/proxy/__init__.py ``` # Run Dashboard Dashboard is currently under development and not yet bundled with `pip` packages. To run dashboard, you must checkout the source. Dashboard is written in Typescript and SCSS, so let's build it first using: ```console ❯ make dashboard ``` Also build the embedded `Chrome DevTools` if you plan on using it: ```console ❯ make devtools ``` Now start `proxy.py` with dashboard plugin and by overriding root directory for static server: ```console ❯ proxy --enable-dashboard --static-server-dir dashboard/public ...[redacted]... - Loaded plugin proxy.http.server.HttpWebServerPlugin ...[redacted]... - Loaded plugin proxy.dashboard.dashboard.ProxyDashboard ...[redacted]... - Loaded plugin proxy.dashboard.inspect_traffic.InspectTrafficPlugin ...[redacted]... - Loaded plugin proxy.http.inspector.DevtoolsProtocolPlugin ...[redacted]... - Loaded plugin proxy.http.proxy.HttpProxyPlugin ...[redacted]... - Listening on ::1:8899 ...[redacted]... - Core Event enabled ``` Currently, enabling dashboard will also enable all the dashboard plugins. Visit dashboard: ```console ❯ open http://localhost:8899/dashboard/ ``` ## Inspect Traffic ***This is a WIP and may not work as documented*** Wait for embedded `Chrome Dev Console` to load. Currently, detail about all traffic flowing through `proxy.py` is pushed to the `Inspect Traffic` tab. However, received payloads are not yet integrated with the embedded dev console. Current functionality can be verified by opening the `Dev Console` of dashboard and inspecting the websocket connection that dashboard established with the `proxy.py` server. [](https://github.com/abhinavsingh/proxy.py) # Chrome DevTools Protocol For scenarios where you want direct access to `Chrome DevTools` protocol websocket endpoint, start `proxy.py` as: ```console ❯ proxy --enable-devtools --enable-events ``` Now point your CDT instance to `ws://localhost:8899/devtools`. # Frequently Asked Questions ## Threads vs Threadless ### `v1.x` `proxy.py` used to spawn new threads for handling client requests. ### `v2.0+` `proxy.py` added support for threadless execution of client requests using `asyncio`. ### `v2.4.0+` Threadless execution was turned ON by default for `Python 3.8+` on `mac` and `linux` environments. `proxy.py` threadless execution has been reported safe on these environments by our users. If you are running into trouble, fallback to threaded mode using `--threaded` flag. For `windows` and `Python < 3.8`, you can still try out threadless mode by starting `proxy.py` with `--threadless` flag. If threadless works for you, consider sending a PR by editing `_env_threadless_compliant` method in the `proxy/common/constants.py` file. ## SyntaxError: invalid syntax `proxy.py` is strictly typed and uses Python `typing` annotations. Example: ```python >>> my_strings : List[str] = [] >>> #############^^^^^^^^^##### ``` Hence a Python version that understands typing annotations is required. Make sure you are using `Python 3.6+`. Verify the version before running `proxy.py`: `❯ python --version` All `typing` annotations can be replaced with `comment-only` annotations. Example: ```python >>> my_strings = [] # List[str] >>> ################^^^^^^^^^^^ ``` It will enable `proxy.py` to run on Python `pre-3.6`, even on `2.7`. However, as all future versions of Python will support `typing` annotations, this has not been considered. ## Unable to load plugins Make sure plugin modules are discoverable by adding them to `PYTHONPATH`. Example: `PYTHONPATH=/path/to/my/app proxy --plugins my_app.proxyPlugin` ```console ...[redacted]... - Loaded plugin proxy.HttpProxyPlugin ...[redacted]... - Loaded plugin my_app.proxyPlugin ``` OR, simply pass fully-qualified path as parameter, e.g. `proxy --plugins /path/to/my/app/my_app.proxyPlugin` ## Unable to connect with proxy.py from remote host Make sure `proxy.py` is listening on correct network interface. Try following flags: - For IPv6 `--hostname ::` - For IPv4 `--hostname 0.0.0.0` ## Basic auth not working with a browser Most likely it's a browser integration issue with system keychain. - First verify that basic auth is working using `curl` `curl -v -x username:password@localhost:8899 https://httpbin.org/get` - See [this thread](https://github.com/abhinavsingh/proxy.py/issues/89#issuecomment-534845710) for further details. ## Docker image not working on macOS It's a compatibility issue with `vpnkit`. See [moby/vpnkit exhausts docker resources](https://github.com/abhinavsingh/proxy.py/issues/43) and [Connection refused: The proxy could not connect](https://github.com/moby/vpnkit/issues/469) for some background. ## GCE log viewer integration for proxy.py A starter [fluentd.conf](https://github.com/abhinavsingh/proxy.py/blob/develop/fluentd.conf) template is available. 1. Copy this configuration file as `proxy.py.conf` under `/etc/google-fluentd/config.d/` 2. Update `path` field to log file path as used with `--log-file` flag. By default `/tmp/proxy.log` path is tailed. 3. Reload `google-fluentd`: `sudo service google-fluentd restart` Now `proxy.py` logs can be browsed using [GCE log viewer](https://console.cloud.google.com/logs/viewer). ## ValueError: filedescriptor out of range in select `proxy.py` is made to handle thousands of connections per second without any socket leaks. 1. Make use of `--open-file-limit` flag to customize `ulimit -n`. 2. Make sure to adjust `--backlog` flag for higher concurrency. If nothing helps, [open an issue](https://github.com/abhinavsingh/proxy.py/issues/new) with `requests per second` sent and output of following debug script: ```console ❯ ./helper/monitor_open_files.sh