OpenGFW: A Go repository from HynoR

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OpenGFW is a flexible, easy-to-use, open source implementation of GFW on Linux that's in many ways more powerful than the real thing. It's cyber sovereignty you can have on a home router.

Caution

This project is still in very early stages of development. Use at your own risk.

Note

We are looking for contributors to help us with this project, especially implementing analyzers for more protocols!!!

Features

Full IP/TCP reassembly, various protocol analyzers
- HTTP, TLS, DNS, SSH, SOCKS4/5, WireGuard, and many more to come
- "Fully encrypted traffic" detection for Shadowsocks, etc. (https://gfw.report/publications/usenixsecurity23/data/paper/paper.pdf)
- Trojan (proxy protocol) detection based on Trojan-killer (https://github.com/XTLS/Trojan-killer)
- [WIP] Machine learning based traffic classification
Full IPv4 and IPv6 support
Flow-based multicore load balancing
Connection offloading
Powerful rule engine based on expr
Flexible analyzer & modifier framework
Extensible IO implementation (only NFQueue for now)
[WIP] Web UI

Use cases

Ad blocking
Parental control
Malware protection
Abuse prevention for VPN/proxy services
Traffic analysis (log only mode)

Usage

Build

go build

Run

export OPENGFW_LOG_LEVEL=debug
./OpenGFW -c config.yaml rules.yaml

Example config

io:
  queueSize: 1024
  local: true # set to false if you want to run OpenGFW on FORWARD chain

workers:
  count: 4
  queueSize: 16
  tcpMaxBufferedPagesTotal: 4096
  tcpMaxBufferedPagesPerConn: 64
  udpMaxStreams: 4096

Example rules

Analyzer properties

For syntax of the expression language, please refer to Expr Language Definition.

- name: block v2ex http
  action: block
  expr: string(http?.req?.headers?.host) endsWith "v2ex.com"

- name: block v2ex https
  action: block
  expr: string(tls?.req?.sni) endsWith "v2ex.com"

- name: block shadowsocks
  action: block
  expr: fet != nil && fet.yes

- name: block trojan
  action: block
  expr: trojan != nil && trojan.yes

- name: v2ex dns poisoning
  action: modify
  modifier:
    name: dns
    args:
      a: "0.0.0.0"
      aaaa: "::"
  expr: dns != nil && dns.qr && any(dns.questions, {.name endsWith "v2ex.com"})

- name: block google socks
  action: block
  expr: string(socks?.req?.addr) endsWith "google.com" && socks?.req?.port == 80

- name: block wireguard by handshake response
  action: drop
  expr: wireguard?.handshake_response?.receiver_index_matched == true

- name: block bilibili geosite
  action: block
  expr: geosite(string(tls?.req?.sni), "bilibili")

- name: block CN geoip
  action: block
  expr: geoip(string(ip.dst), "cn")

Supported actions

allow: Allow the connection, no further processing.
block: Block the connection, no further processing.
drop: For UDP, drop the packet that triggered the rule, continue processing future packets in the same flow. For TCP, same as block.
modify: For UDP, modify the packet that triggered the rule using the given modifier, continue processing future packets in the same flow. For TCP, same as allow.

HynoR/OpenGFW