# Transparent Proxy with cgroup v2



## Introduction

cgproxy will transparent proxy anything running in specific cgroup. It resembles with *proxychains* and *tsock*, but without their disadvantages, and more powerfull.

It aslo supports global transparent proxy and gateway proxy. See [Global transparent proxy](#global-transparent-proxy) and  [Gateway proxy](#gateway-proxy).

<!--ts-->
   * [Transparent Proxy with cgroup v2](#transparent-proxy-with-cgroup-v2)
      * [Introduction](#introduction)
      * [Prerequest](#prerequest)
      * [How to install](#how-to-install)
      * [Default usage](#default-usage)
      * [Configuration](#configuration)
      * [Global transparent proxy](#global-transparent-proxy)
      * [Gateway proxy](#gateway-proxy)
      * [Other useful tools provided in this project](#other-useful-tools-provided-in-this-project)
      * [NOTES](#notes)
      * [TIPS](#tips)
      * [Licences](#licences)

<!-- Added by: fancy, at: Sat 16 May 2020 03:12:07 PM HKT -->

<!--te-->

## Prerequest

- cgroup2

  Both cgroup and cgroup2 are enabled in linux by default. So you don't have to do anything about this.
  - `systemd-cgls` to see the cgroup hierarchical tree.
  - Why cgroup v2?  Because simple, elegant and intuitive.

- TPROXY

  A process listening on port (e.g.  12345)  to accept iptables TPROXY, for example v2ray's dokodemo-door in tproxy mode.

## How to install

```bash
mkdir build && cd build && cmake .. && make && make install
```

- It is alreay in [archlinux AUR](https://aur.archlinux.org/packages/?K=cgproxy). 

- DEB and RPM are packaged in [release page](https://github.com/springzfx/cgproxy/releases).

## Default usage

- First enable and start service

  ```bash
  sudo systemctl enable --now cgproxy.service
  ```
  
- Then prefix with cgproxy with your command, just like proxychains

  ```bash
  cgproxy [--debug] <CMD>
  ```

- For example, test proxy

  ```bash
  cgproxy curl -vI https://www.google.com
  ```

- To completely stop
  ```
  sudo systemctl disable --now cgproxy.service
  ```

## Configuration

Config file: **/etc/cgproxy/config.json**

```json
{
    "cgroup_noproxy": ["/system.slice/v2ray.service"],
    "cgroup_proxy": [],
    "enable_dns": true,
    "enable_gateway": false,
    "enable_ipv4": true,
    "enable_ipv6": true,
    "enable_tcp": true,
    "enable_udp": true,
    "port": 12345
}
```

- **port** tproxy listenning port
- **cgroup_noproxy** cgroup array that no need to proxy, `/noproxy.slice` is preserved
- **cgroup_proxy** cgroup array that need to proxy, `/proxy.slice` is preserved
- **enable_gateway** enable gateway proxy for local devices
- **enable_dns** enable dns to go to proxy
- **enable_tcp**
- **enable_udp**
- **enable_ipv4**
- **enable_ipv6**

**Note**: cgroup in configuration need to be exist, otherwise ignored

If you changed config, remember to restart service

```bash
sudo systemctl restart cgproxy.service
```

## Global transparent proxy

- Set `"cgroup_proxy":["/"]`  in configuration, this will proxy all connection

- Allow your proxy program (v2ray) direct to internet to avoid loop. Two ways:
  
  - active way, run command
    
    example: `cgnoproxy sudo v2ray -config config_file`
    
    example: `cgnoproxy qv2ray`
    
  - passive way,  set it's cgroup in configuration,  very useful for service
  
      example:  `"cgroup_noproxy":["/system.slice/v2ray.service"]`
  
- Finally, restart cgproxy service, that's all

## Gateway proxy

- Set `"enable_gateway":true` in configuration
- And allow your proxy software (v2ray) direct to internet if necessary, described above
- Other device set this host as gateway, and set public dns if need

## Other useful tools provided in this project

- `cgnoproxy` run program wihout proxy, very useful in global transparent proxy

  ```bash
  cgnoproxy [--debug] <CMD> 
  ```
  
- `cgattach` attach specific process pid to specific cgroup which will create if not exist , cgroup can be only one level down exist cgroup, otherwise created fail.

  ```bash
  cgattch <pid> <cgroup>
  # example
  cgattch 9999 /proxy.slice
  ```

## NOTES

- v2ray TPROXY need root or special permission, use [service](https://github.com/springzfx/cgproxy/blob/v3.x/v2ray_config/v2ray.service) or
  
  ```bash
  sudo setcap "cap_net_admin,cap_net_bind_service=ep" /usr/lib/v2ray/v2ray
  ```

- Why not outbound mark solution, because in v2ray [when `"localhost"` is used, out-going DNS traffic is not controlled by V2Ray](https://www.v2fly.org/en/configuration/dns.html), so no mark at all, that's pity.

## TIPS

- `systemd-cgls` to see the cgroup hierarchical tree.
- Check cgroup2 support `findmnt -t cgroup2`
- Offer you v2ray service and full config exmaple in [v2ray_config](https://github.com/springzfx/cgproxy/tree/master/v2ray_config)
- Offer you qv2ray config example
  

![Qv2ray config example](https://i.loli.net/2020/04/28/bdQBzUD37FOgfvt.png)

## Licences

cgproxy is licenced under [![License: GPL v3](https://img.shields.io/badge/License-GPL%20v2-blue.svg)](https://www.gnu.org/licenses/gpl-2.0)