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.

Prerequest

• cgroup2

  For now, linux default using cgroup v1 for compatibility, this project need cgroup v2, you need disable cgroup v1 and enable cgroup v2 in your system.

• 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

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

It is alreay in archlinux AUR.

How to use

• First enable service

  sudo systemctl enable --now cgproxy.service
  sudo systemctl status cgproxy.service
  

• Then prefix with cgproxy with you command, just like proxychains

  cgproxy <CMD>
  

• For example, test proxy

  cgproxy curl -vIs https://www.google.com
  

More config in /etc/cgproxy.conf:

## any process in this cgroup will be proxied
## must start with slash '/'
proxy_cgroup="/proxy.slice"

## listening port of another proxy process, for example v2ray 
port=12345

## if you set to false, it's traffic won't go through proxy, but still can go direct to internet
enable_tcp=true
enable_udp=true
enable_ipv4=true
enable_ipv6=true

## v2ray outbound mark
## only useful if v2ray process is also in proxy_cgroup, for example, you want to proxy whole userspace,
## and v2ray is also running in userspace
## otherwise ignore this
v2ray_so_mark=255

## do not modify this if you don't known what you are doing
mark=2333
table=100

NOTES

• cgattach attach pid to specific cgroup, and has suid bit set by default, be careful to use on multi-user server for securiry. To avoid this situation, you can remove the suid bit , then it will fallback to use sudo, with visudo you can restrict permission or set NOPASSWD for youself.
• TPROXY need root or cap_net_admin capability whatever process is listening on port, v2ray as example: sudo setcap cap_net_admin+ep /usr/lib/v2ray/v2ray

TIPS

• systemd-cgls to see the cgroup hierarchical tree.