Cilium is open source software for providing and transparently securing network connectivity and loadbalancing between application containers and services deployed using Linux container management platforms like Docker and Kubernetes.
A new Linux kernel technology called eBPF is at the foundation of Cilium, which enables the dynamic insertion of BPF bytecode into the Linux kernel. Cilium generates eBPF programs for each individual application container to provide networking, security, loadbalancing and visibility.
- Security Policies: Enforcement of security policies at application (L7) and networking (L3-L4) layer. Application level policies include filtering of HTTP protocol properties such as method, path, host, and headers. Networking policies include container/pod/service interconnectivity rules based on labels, restriction of traffic to certain CIDR and/or port ranges for both ingress and egress.
- Networking: A simple flat Layer 3 network with the ability to span multiple clusters connects all application containers and services. Simple IP allocation using host scope allocators (dedicated /24 per cluster node for IPv4, dedicated /112 per cluster node for IPv6). Choice of either integrating with Linux routing to run a routing daemon or to create an overlay network using encapsulation (VXLAN/Geneve).
- Load balancing: Distributed load balancing for east-west traffic from application container to application container, e.g. implementation of Kubernetes services. North-south traffic to load balance external traffic, e.g. implementation of Kubernetes ingress. All load-balancing performed with direct server return (DSR) by default for improved performance.
- Troubleshooting: Built-in troubleshooting tools providing an alternative to traditional tcpdump troubleshooting techniques.
- Integrations:
- Network plugin integrations: CNI, libnetwork
- Container runtime events: containerd
- Kubernetes: NetworkPolicy, Labels, Ingress, Service
- Logging: fluentd
- Why Cilium?
- Getting Started with Vagrant
- Architecture
- Administrator Guide
- Frequently Asked Questions
- Contributing
Berkeley Packet Filter (BPF) is a Linux kernel bytecode interpreter originally introduced to filter network packets, e.g. for tcpdump and socket filters. The BPF instruction set and surrounding architecture has recently been significantly reworked with additional data structures such as hash tables and arrays for keeping state as well as additional actions to support packet mangling, forwarding, encapsulation, etc. Furthermore, a compiler back end for LLVM allows for programs to be written in C and compiled into BPF instructions. An in-kernel verifier ensures that BPF programs are safe to run and a JIT compiler converts the BPF bytecode to CPU architecture specific instructions for native execution efficiency. BPF programs can be run at various hooking points in the kernel such as for incoming packets, outgoing packets, system calls, kprobes, uprobes, tracepoints, etc.
BPF continues to evolve and gain additional capabilities with each new Linux release. Cilium leverages BPF to perform core data path filtering, mangling, monitoring and redirection, and requires BPF capabilities that are in any Linux kernel version 4.8.0 or newer (the latest current stable Linux kernel is 4.10.x).
Many Linux distributions including CoreOS, Debian, Docker's LinuxKit, Fedora,
and Ubuntu already ship kernel versions >= 4.8.x. You can check your Linux
kernel version by running uname -a. If you are not yet running a recent
enough kernel, check the Documentation of your Linux distribution on how to run
Linux kernel 4.9.x or later.
For more detail on kernel versions, see: Prerequisites
XDP is a further step in evolution and enables to run a specific flavor of BPF programs from the network driver with direct access to the packet's DMA buffer. This is, by definition, the earliest possible point in the software stack, where programs can be attached to in order to allow for a programmable, high performance packet processor in the Linux kernel networking data path.
Further information about BPF and XDP targeted for developers can be found in the BPF and XDP reference guide.
See the Installation instructions
- DockerCon, April 18, 2017: Cilium - Network and Application Security with BPF and XDP
- CNCF/KubeCon Meetup, March 28, 2017: Linux Native, HTTP Aware Network Security
- Docker Distributed Systems Summit, Berlin, Oct 2016: Slides, Video
- NetDev1.2, Tokyo, Sep 2016 - cls_bpf/eBPF updates since netdev 1.1: Slides, Video
- NetDev1.2, Tokyo, Sep 2016 - Advanced programmability and recent updates with tc’s cls_bpf: Slides, Video
- ContainerCon NA, Toronto, Aug 2016 - Fast IPv6 container networking with BPF & XDP: Slides
- Software Gone Wild by Ivan Pepelnjak, Oct 2016: Blog, MP3
- OVS Orbit by Ben Pfaff, May 2016: Blog, MP3
- Cilium for Network and Application Security with BPF and XDP, Apr 2017: Blog
- Cilium, BPF and XDP, Google Open Source Blog, Nov 2016: Blog
- The developer community is hanging out on zoom on a weekly basis to chat. Everybody is welcome.
- Weekly, Monday, 9:00 am PT, 12:00 pm (noon) ET, 6:00 pm CEST
- Join zoom
If you have any questions feel free to contact us on Slack
The cilium user space components are licensed under the Apache License, Version 2.0. The BPF code templates are licensed under the General Public License, Version 2.0.