The xyz.sh wrapper adds no telemetry and does not perform hidden actions. You can read the full source on the page or with curl -fsSL xyz.sh/ .sh before running it. Piping a remote script to bash is still a risk — review the source first. This script only changes two sysctl values (the fq qdisc and BBR congestion control) and writes the file above.

Which operating systems are supported?

Declared support: Debian, Ubuntu, CentOS, Rocky Linux, and AlmaLinux. The script detects the distribution and asks before continuing on an unrecognized OS. Syntax was checked with bash -n and ShellCheck; installer scripts have not been end-to-end verified on every listed distribution.

Yes. Run it as root or via sudo bash. The script exits with a message if it is not root.

How do I uninstall or revert it?

Delete /etc/sysctl.d/99-xyz-bbr.conf, then run sysctl --system, or set congestion control back (often cubic). The script never replaces the kernel, so no kernel rollback is involved.

Enable BBR Tutorial (TCP BBR on Debian, Ubuntu, CentOS)

Q: What if my kernel has no BBR?

Linux 4.9+ with tcp_bbr available is required. If the module is missing, the script exits with an error and will not compile or install a new kernel.

This tutorial shows how to enable in-tree TCP BBR on a Linux VPS with xyz.sh/bbr. It only changes sysctl settings, does not replace the kernel, and does not claim any speed-up or benchmark result.

Prerequisites

You need Linux 4.9 or later with the tcp_bbr module available, plus root. Typical Debian, Ubuntu, CentOS, Rocky, and AlmaLinux kernels include the module, but the script checks the machine itself.

If the module is missing, the script exits with an error and will not compile or install a new kernel.

Steps

As root, run: curl -fsSL xyz.sh/bbr | bash

After confirmation, the script writes /etc/sysctl.d/99-xyz-bbr.conf with net.core.default_qdisc = fq and net.ipv4.tcp_congestion_control = bbr, then applies it with sysctl -p.

To inspect the current state only, use bash -s -- --status.

How to verify

Run curl -fsSL xyz.sh/bbr | bash -s -- --status, or check that sysctl net.ipv4.tcp_congestion_control is bbr.

This tutorial does not compare BBR with other congestion controls; results vary by path and load.

How to revert

There is no --uninstall flag. Delete /etc/sysctl.d/99-xyz-bbr.conf, then run sysctl --system, or set net.ipv4.tcp_congestion_control back to its previous value (often cubic).