Linux

Universal installation. Works on any distribution: Ubuntu, Debian, Fedora, Alpine, Arch, and others.

Install

curl -fsSL https://raw.githubusercontent.com/DanielLavrushin/b4/main/install.sh | sh

Or with wget:

wget -qO- https://raw.githubusercontent.com/DanielLavrushin/b4/main/install.sh | sh

The installer detects the architecture automatically, places the binary in /usr/local/bin, and creates the configuration in /etc/b4.

For a non-interactive install (default settings, no prompts):

curl -fsSL https://raw.githubusercontent.com/DanielLavrushin/b4/main/install.sh | sh -s -- --quiet

Service control

systemd (Ubuntu, Debian, Fedora, and most distributions)

systemctl start b4
systemctl stop b4
systemctl restart b4
systemctl status b4
systemctl enable b4      # autostart on boot

View logs:

journalctl -u b4 -f

OpenRC (Alpine)

rc-service b4 start
rc-service b4 stop
rc-service b4 restart
rc-update add b4 default   # autostart on boot

Paths

What	Where
Binary	/usr/local/bin/b4
Configuration	/etc/b4/b4.json
Service (systemd)	/etc/systemd/system/b4.service
Service (OpenRC/SysV)	/etc/init.d/b4

Kernel modules

b4 uses NFQUEUE to intercept packets. The required kernel modules are usually loaded automatically when the service starts. If you run into issues, load them manually:

modprobe nfnetlink_queue
modprobe xt_NFQUEUE
modprobe nf_conntrack

To verify:

lsmod | grep nfqueue

LXC containers

In LXC containers, kernel modules must be loaded on the host. Add to the container config:

lxc.cgroup2.devices.allow: c 10:200 rwm
features: nesting=1,keyctl=1