Gatekeeper

What is Gatekeeper?

Gatekeeper is the first open source DDoS protection system. It is designed to scale to any peak bandwidth, so it can withstand DDoS attacks both of today and of tomorrow. In spite of the geographically distributed architecture of Gatekeeper, the network policy that describes all decisions that have to be enforced on the incoming traffic is centralized. This centralized policy enables network operators to leverage distributed algorithms that would not be viable under very high latency (e.g. distributed databases) and to fight multiple multi-vector DDoS attacks at once.

The intended users of Gatekeeper are network operators of institutions, service and content providers, enterprise networks, etc. It is not intended to be used by individual Internet users.

For more information, see the Gatekeeper wiki.

How to Set Up

Configure Hugepages

DPDK requires the use of hugepages; instructions for mounting hugepages are available in the requirements documentation. On many systems, the following hugepages setup is sufficient:

$ echo 256 | sudo tee /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages

Enable the kernel module vfio-pci

The Linux kernel module vfio-pci is needed to bind NICs to DPDK/Gatekeeper. In order for vfio-pci to work, both the BIOS and the kernel must support it. BIOSes must have VT-d enabled. BIOSes may identify VT-d as "Intel (R) VT for Directed I/O", "Intel (R) VT-d Feature", "Intel VT-d", "VT-d", or similar variations; for more examples, search "BIOS VT-d" on Google Images. Some BIOS may require that an option called "Intel (R) Virtualization Technology" (or variations of this string) to be enabled before VT-d can be enabled.

To check that VT-d is enabled at the BIOS, run the following command after Linux boots up:

$ dmesg | grep -e DMAR

If the command above returns some lines, VT-d should be enabled. Otherwise, one has to go back to the BIOS to enable it. More information on how to check that VT-d is enabled at the BIOS is available on this page.

Once VT-d is enabled at the BIOS, one must ensure that the kernel supports IOMMU. Notice that one needs a kernel version greater than 3.6 to support IOMMU. One can verify if the running kernel has IOMMU enabled by default with the following command:

$ grep CONFIG_INTEL_IOMMU_DEFAULT_ON /boot/config-`uname -r`

Most likely, the command above will output # CONFIG_INTEL_IOMMU_DEFAULT_ON is not set, that is, the running kernel does not have IOMMU enabled by default. Alternatives ways to check for kernel build options (i.e. CONFIG_INTEL_IOMMU_DEFAULT_ON) is available on this page.

If the kernel does not have IOMMU enabled by default, one has to pass the kernel boot parameter intel_iommu=on via GRUB. For information on the why the boot parameter intel_iommu=on is needed, see this page. One can check if the running kernel received this parameter with the command below:

$ cat /proc/cmdline | grep intel_iommu=on

If the running kernel has not received the parameter intel_iommu=on, add it to GRUB, and reboot the machine. Information on how to add a boot parameter to GRUB is found here.

Once VT-d is enabled at the BIOS and the kernel supports IOMMU, one can verify that everything is all set with one of the following commands:

$ ls /sys/kernel/iommu_groups

OR

$ dmesg | grep -ie 'IOMMU\s\+enabled'

Everything is all set if the outputs of the commands above are not empty.

Option 1: Obtain Packages

Gatekeeper Debian packages are available for Ubuntu 24.04 LTS at the project's Releases page.

Install

Once the packages are downloaded, they can be installed with the commands below:

$ tar -zxvf gatekeeper-ubuntu-24.04-packages.tar.gz
$ cd gatekeeper-ubuntu-24.04-packages
$ sudo dpkg -i gatekeeper-bird_*_amd64.deb gatekeeper_*_amd64.deb

Configure Gatekeeper

When installed via Debian packages, Gatekeeper configuration files are located in /etc/gatekeeper. You should edit at least the net.lua file, and set the front_ports, front_ips, back_ports and back_ips variables according to your environment.

The other Lua files configure different Gatekeeper functional blocks. Please refer to the project's wiki for further information on whether these need to be changed in your setup.

You also need to edit the /etc/gatekeeper/envvars file and set the GATEKEEPER_INTERFACES variable to the PCI addresses of the network adapters to be bound to DPDK. These can found using the lshw command. For example:

# lshw -c network -businfo
Bus info          Device     Class          Description
=======================================================
pci@0000:08:00.0  eth0       network        I350 Gigabit Network Connection
pci@0000:08:00.1  eth1       network        I350 Gigabit Network Connection
...

Given this output, set GATEKEEPER_INTERFACES as below:

GATEKEEPER_INTERFACES="08:00.0 08:00.1"

In the same file, you can optionally specify Environmental Abstraction Layer options in the DPDK_ARGS variable and Gatekeeper-specific options in GATEKEEPER_ARGS.

How to run

Run the commands below to start Gatekeeper and to ensure it is started automatically on reboots.

$ sudo systemctl start gatekeeper
$ sudo systemctl enable gatekeeper

Option 2: Build from Source

Install Dependencies

Install the following software dependencies:

$ sudo apt-get update
$ sudo apt-get -y -q install git clang devscripts doxygen libhugetlbfs-bin \
    build-essential gcc-multilib linux-headers-`uname -r` libmnl0 libmnl-dev \
    libkmod2 libkmod-dev libnuma-dev libelf1 libelf-dev libc6-dev-i386 \
    autoconf flex bison libncurses5-dev libreadline-dev python3 \
    python3-pyelftools libcap-dev libcap2 meson ninja-build pkg-config

Note: Both libmnl0 and libmnl-dev are needed to compile and run gatekeeper, but only libmnl0 is needed for simply running gatekeeper. Both libkmod2 and libkmod-dev are needed to compile and run gatekeeper, but only libkmod2 is needed for simply running gatekeeper. libnuma-dev is needed to compile the latest DPDK and to support NUMA systems. The package libelf-dev is needed to compile DPDK with support to reading BPF programs from ELF files, but only libelf1 is needed to run it. The package libc6-dev-i386 is needed to compile the BPF programs in the folder bpf/. The autoconf, flex, bison, libncurses5-dev, and libreadline-dev packages are for BIRD. The devscripts package is used to build Gatekeeper Debian packages. The packages python3 and python3-pyelftools are needed to build DPDK and to run Python scripts such as dpdk-devbind.py. libcap-dev is needed to compile Gatekeeper, but only libcap2 is needed to run Gatekeeper. meson and ninja-build are needed for building DPDK. pkg-config is needed to compile Gatekeeper.

To use DPDK, make sure you have all of the environmental requirements.

Clone Repository

Clone the Gatekeeper repository, including the submodules that contain Gatekeeper dependencies:

$ git clone --recursive http://github.com/AltraMayor/gatekeeper.git

If you do not use the --recursive clone option, you need to obtain the submodules that contain the dependences from within the gatekeeper directory:

$ git submodule init
$ git submodule update

Compile

This section explains how to build Gatekeeper manually. If you want to build Debian packages, refer to the section How to build packages.

While in the gatekeeper directory, run the setup script:

$ . setup.sh

This script compiles DPDK, LuaJIT, and BIRD, and loads the needed kernel modules. Additionally, it saves the interface names and their respective PCI addresses in the file lua/if_map.lua so that interface names can be used in the Gatekeeper configuration files.

Once DPDK and LuaJIT are compiled, gatekeeper can be compiled:

$ make

Configure Network Adapters

Before gatekeeper can be used, the network adapters must be bound to DPDK. For this, you can use the script dependencies/dpdk/usertools/dpdk-devbind.py. For example:

$ sudo dependencies/dpdk/usertools/dpdk-devbind.py --bind=vfio-pci enp131s0f0

This command binds the interface enp131s0f0 to the vfio-pci driver so that frames can be passed directly to DPDK instead of the kernel. Note that this binding must take place after Gatekeeper is setup in the steps above so that the bound interface appears in the list of interfaces in lua/if_map.lua.

How to Run

Once gatekeeper is compiled and the environment is configured correctly, run:

$ sudo build/gatekeeper [EAL OPTIONS] -- [GATEKEEPER OPTIONS]

Where [EAL OPTIONS] are specified before a double dash and represent the parameters for DPDK's Environmental Abstraction Layer and [GATEKEEPER OPTIONS] are specified after the double dash and represent Gatekeeper-specific options.

The early configuration of the system, including device and memory configuration in DPDK, will be logged to stdout. Once Gatekeeper is booted, all information is output to the Gatekeeper log.

How to build packages

Gatekeeper Debian packages can be built with the commands below. They are meant to be run from the repository root and assume the git submodules have been pulled, and that the build dependencies have been installed, as instructed above. Gatekeeper and the submodules will be automatically compiled during the package build process.

$ tar --exclude-vcs -Jcvf ../gatekeeper_1.2.0.orig.tar.xz -C .. gatekeeper
$ debuild -uc -us

The Gatekeeper package will be available in the parent directory.