OpenGFW

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OpenGFW is your very own DIY Great Firewall of China (https://en.wikipedia.org/wiki/Great_Firewall), available as a flexible, easy-to-use open source program on Linux. Why let the powers that be have all the fun? It's time to give power to the people and democratize censorship. Bring the thrill of cyber-sovereignty right into your home router and start filtering like a pro - you too can play Big Brother.

Telegram group: https://t.me/OpGFW

[!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, QUIC, DNS, SSH, SOCKS4/5, WireGuard, and many more to come
  • "Fully encrypted traffic" detection for Shadowsocks, etc. (https://gfw.report/publications/usenixsecurity23/en/)
  • Trojan (proxy protocol) detection
  • [WIP] Machine learning based traffic classification
• Full IPv4 and IPv6 support
• Flow-based multicore load balancing
• Connection offloading
• Powerful rule engine based on expr
• Hot-reloadable rules (send SIGHUP to reload)
• 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)
• Help you fulfill your dictatorial ambitions

Usage

Build

go build

Run

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

OpenWrt

OpenGFW has been tested to work on OpenWrt 23.05 (other versions should also work, just not verified).

Install the dependencies:

# For OpenWrt version 22.03 and later (nftables based firewall)
opkg install kmod-nft-queue kmod-nf-conntrack-netlink

# For OpenWrt versions prior to 22.03 (excluding 22.03, iptables based firewall)
opkg install kmod-ipt-nfqueue iptables-mod-nfqueue kmod-nf-conntrack-netlink

Example config

io:
  queueSize: 1024
  rcvBuf: 4194304
  sndBuf: 4194304
  local: true # set to false if you want to run OpenGFW on FORWARD chain
  rst: false # set to true if you want to send RST for blocked TCP connections, local=false only

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

# The path to load specific local geoip/geosite db files.
# If not set, they will be automatically downloaded from https://github.com/Loyalsoldier/v2ray-rules-dat
# geo:
#   geoip: geoip.dat
#   geosite: geosite.dat

Example rules

Analyzer properties

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

# A rule must have at least one of "action" or "log" field set.
- name: log horny people
  log: true
  expr: let sni = string(tls?.req?.sni); sni contains "porn" || sni contains "hentai"

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

- name: block and log shadowsocks
  action: block
  log: true
  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")

- name: block cidr
  action: block
  expr: cidr(string(ip.dst), "192.168.0.0/16")

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.