lavrushin/b4 repository overview

⁠B4 — Network Packet Processor for DPI Circumvention

B4 is a netfilter-queue-based packet processor that bypasses Deep Packet Inspection (DPI). It intercepts and modifies network packets in real-time using various desync strategies.

• Web UI for configuration and monitoring (port 7000)
• TCP/UDP packet manipulation with multiple desync modes
• DNS spoofing and fragmentation
• Domain-based filtering with geosite.dat support

GitHub: github.com/DanielLavrushin/b4⁠

⁠Quick Start

docker run --network host \
  --cap-add NET_ADMIN --cap-add NET_RAW --cap-add SYS_MODULE \
  -v /etc/b4:/etc/b4 \
  lavrushin/b4:latest --config /opt/etc/b4/b4.json

Web UI: http://localhost:7000⁠

⁠Docker Compose

services:
  b4:
    image: lavrushin/b4:latest
    container_name: b4
    network_mode: host
    cap_add:
      - NET_ADMIN
      - NET_RAW
      - SYS_MODULE
    volumes:
      - ./config:/etc/b4
    command: ["--config", "/etc/b4/b4.json"]
    restart: unless-stopped

⁠Requirements

• Linux host only - b4 uses netfilter queue (NFQUEUE) which is a Linux kernel feature
• --network host is mandatory — b4 must access the host network stack directly
• Capabilities: NET_ADMIN (firewall rules), NET_RAW (raw sockets), SYS_MODULE (kernel module loading)
• Host kernel must have nfqueue support (xt_NFQUEUE, nf_conntrack modules)