Snabb - A toolkit for user-space networking (FOSDEM 2018)
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By Diego Pino. Snabb is a toolkit for developing user-space network functions. A network function (filtering, NAT, encapsulation) is any program that manipulates network traffic. Snabb eases the effort to write such programs. Snabb fits in the category of user-space networking. Snabb by-passes the Linux kernel talking directly to the hardware. This makes Snabb a very convenient tool for high-performance networking. Unlike other user-space toolkits such as DPDK or VPP, Snabb is entirely developed in Lua which significantly lowers the adoption barrier. In this talk I introduce the Snabb toolkit. Through real-world examples you will learn how Snabb works and even how to start prototyping your own network functions. (c) FOSDEM 2018 Brussels, 3 & 4 February 2018 https://fosdem.org/2018/schedule/event/snabb/
![PACKETSPACKETS
struct packet {
uint16_t length;
unsigned char data[10*1024];
};](https://image.slidesharecdn.com/diegopino-snabb-atoolkitforuser-spacenetworking-180207093228/85/Snabb-A-toolkit-for-user-space-networking-FOSDEM-2018-22-320.jpg)
![LINKSLINKS
struct link {
struct packet *packets[1024];
// the next element to be read
int read;
// the next element to be written
int write;
};](https://image.slidesharecdn.com/diegopino-snabb-atoolkitforuser-spacenetworking-180207093228/85/Snabb-A-toolkit-for-user-space-networking-FOSDEM-2018-23-320.jpg)
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Snabb - A toolkit for user-space networking (FOSDEM 2018)
- 1. SNABBSNABB A TOOLKIT FOR USER-SPACE NETWORKINGA TOOLKIT FOR USER-SPACE NETWORKING
- 2. TOCTOC What is Snabb? How it works? How to get started?
- 3. WHAT IS SNABB?WHAT IS SNABB? Toolkit for developing network functions in user-space (mostly aimed for high-performance networking)
- 4. WHAT IS A NETWORK FUNCTION?WHAT IS A NETWORK FUNCTION? A program that manipulates network traffic Basic operations: read, forward, drop, modify, create... Combining these primitives we can build any network function
- 5. EXAMPLESEXAMPLES Firewall: read incoming packets, compare to table of rules and execute an action(forward or drop) NAT: read incoming packets, modify headers and forward packet Tunelling: read incoming packets, create a new packet, embed packet into new one and send it
- 7. OFF-THE-SHELL ROUTEROFF-THE-SHELL ROUTER Increasing improvement of commodity hardware: 10Gbps NICs at very affordable prices High-performance equipment is still very expensive Idea: build an analog high-performance router using commodity hardware What so ware to put into this hardware?
- 8. WHAT ABOUT LINUX?WHAT ABOUT LINUX? General-purpose operating system NF is divided in 2 lands: user-space and kernel-space Conclusion: Processing a packet has an inheritent cost (the cost of the OS)
- 9. HIGH-PERFORMANCEHIGH-PERFORMANCE NETWORKINGNETWORKING NIC: 10Gbps; Packet-size: 550-byte 1 packet every 440ns ((1/2,2M)*10^9) CPU: 2,5 Ghz => 1100 cycles per packet
- 10. HIGH-PERFORMANCEHIGH-PERFORMANCE NETWORKINGNETWORKING Packet-size: 64-byte 1 packet every 51 ns Lock/Unlock: 16ns; Cache-miss: 32 ns Link: (Jesper Brouer) "Improving Linux networking performance"
- 11. KERNEL BY-PASSKERNEL BY-PASS Driver in user-space that talks directly to the hw Talk: Other toolkits: DPDK (Intel), VPP/fd.io (Cisco) How to write your own NIC device driver
- 13. SNABBSNABB Project started by Luke Gorrie Mostly developed in Lua Snabb means fast in Swedish
- 14. LUAJITLUAJIT Just-in-time compiler for Lua Extremely fast virtual machine!! Very good integration with C thanks to FFI
- 15. HOW IT WORKS?HOW IT WORKS? A Snabb program (NF) is an app graph Apps are conected together via links Snabb engine processes the program in units called breadths
- 16. NETWORK FUNCTIONNETWORK FUNCTION function run() local c = config.new() config.add(c, "nic", Intel82599, { pci = "0000:04:00.0" }) config.add(c, "filter", PcapFilter, "src port 80") config.add(c, "pcap", Pcap.PcapWriter, "output.pcap") config.link(c, "nic.tx -> filter.input") config.link(c, "filter.output -> pcap.input") engine.configure(c) engine.main()
- 17. NF: APP GRAPHNF: APP GRAPH
- 18. BREADTHSBREADTHS A breadth has two steps: inhale, puts a batch of packets into the graph exhale, processes those packets To inhale, the method pull of the apps is executed (if defined) To exhale, the method push of the apps is executed (if defined)
- 19. # Pull function of included Intel 82599 driver function Intel82599:pull () for i = 1, engine.pull_npackets do if not self.dev:can_receive() then break end local pkt = self.dev:receive() link.transmit(self.output.tx, pkt) end end
- 20. # Push function of included PcapFilter function PcapFilter:push () while not link.empty(self.input.rx) do local p = link.receive(self.input.rx) if self.accept_fn(p.data, p.length) then link.transmit(self.output.tx, p) else packet.free(p) end end end
- 21. PACKET PROCESSINGPACKET PROCESSING Normally only one app of the app graph introduces packets into the graph The method push gives an opportunity to every app to do something with a packet
- 22. PACKETSPACKETS struct packet { uint16_t length; unsigned char data[10*1024]; };
- 23. LINKSLINKS struct link { struct packet *packets[1024]; // the next element to be read int read; // the next element to be written int write; };
- 24. WHAT CAN YOU DO WITH SNABB?WHAT CAN YOU DO WITH SNABB? Anything (that has to do with a packet)
- 25. BUILT-IN CATALOGBUILT-IN CATALOG Libraries: protocols (ipv4, ipv6, tcp), checksum... Apps: drivers, filtering, load generators, sockets... Programs: L2VPN, Lisper, lwAFTR, IPFix, etc
- 26. LWAFTRLWAFTR Component of Lightweigth 4-over-6 (RFC 7596) IPv6 transition technology Deutsche Telekom's Terastream Blog post: Dive into lw4o6
- 27. SNABWALLSNABWALL L7 Firewall (also L3 & L4) Uses: libnDPI & Pflang Funded by NLNet Foundation Site: www.snabbwall.org
- 28. IPFIXIPFIX IP Flow Information Export (RFC 7011) Format for exporting network flows Blog post: IPFix app for Snabb
- 29. DNS SERVICE DISCOVERYDNS SERVICE DISCOVERY Discover Multicast devices in a LAN (RFC6763) Works on network interfaces Blog post: More practical Snabb
- 30. GETTING STARTEDGETTING STARTED $ git clone https://github.com/snabbco/snabb.git $ cd snabb $ make
- 31. LINKSLINKS Github: Slack: Guide: Blog post: https://github.com/snabbco/snabb https://snabb.slack.com Official getting started guide Snabb explained in less than 10 minutes