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Entire Linux Network stack diagram (2024)
- ee99ee 1y agowow
- colordrops 1y agoI'm surprised to realize I'm familiar with most of the stack just from decades of Linux usage and no formal study of the stack.
- elevation 1y agoThis place needs more of this kind of documentation. I failed to use IP tables for years. I bought books. I copied recipes from blog posts. Nothing made sense, everything I did was brittle. Until I finally found a schematic showing the flowchart of a packet through the kernel, which gives the exact order that each rule chain is applied, and where some of the sysctl values are enforced. All of a sudden, I could write rules that did exactly what I wanted, or intelligently choose between rules that have equivalent behaviors in isolation but which could have different performance implications. After studying the schematic, every would just work on the first try. A good schematic makes a world of difference!
- HotGarbage 1y agoWas it this one? https://en.wikipedia.org/wiki/File%3aNetfilter-packet-flow.svg https://en.wikipedia.org/wiki/File%3aNetfilter-packet-flow.s...
- suprjami 1y agoOne of my favourite webpages. Have used it countless times over the years.
- UltraSane 1y agoI use this all the time when writing iptable rules.
- immibis 1y agoThis also isn't complete because it doesn't show code between or around the various tables. I used to think of iptables as dumb filters that manipulate raw packets before/after the rest of the kernel sees them, but this view is wrong, and doesn't explain, for example, how it does NAT. And the answer is it doesn't do NAT. The code is already preparing to do NAT, and that code merely consults the table to find out what kind of NAT it should do. The diagram makes it look like you can just move a NAT rule to a filter or mangle rule because the kernel just applies these tables in sequence anyway, but you can't because they are consulted by different blocks of code for different purposes.
- Koffiepoeder 1y agoCan you share the diagram? Would love to become iptables-enlightened.
- elevation 1y agoEventually I used more detailed diagrams, but this one was like a lightbulb going off: https://www.frozentux.net/iptables-tutorial/images/tables_traverse.jpg https://www.frozentux.net/iptables-tutorial/images/tables_tr... I couldn’t find one that annotated where sysctl configurable were shown. But this is a useful annotation, even if it’s an exercise for the reader.
- eptcyka 1y agoIt is time to be nftables enlightened instead.
- VTimofeenko 1y agoSimilar diagram, right in nftables wiki: https://wiki.nftables.org/wiki-nftables/index.php/Netfilter_hooks#Netfilter_hooks_into_Linux_networking_packet_flows https://wiki.nftables.org/wiki-nftables/index.php/Netfilter_...
- Arch-TK 1y agoIt's more of a netfilter (the thing behind iptables and nftables) diagram rather than just iptables. If you know how iptables maps to that diagram you are very likely to be able to quickly understand how nftables does too.
- eptcyka 1y agoSure, but we really shouldn’t be encouraging the use of iptables in 2025.
- mmh0000 1y agoThat's not realalistic for most of the Linux world. Soooo many systems are still using iptables even though we "should" be using nft everywhere. If you're going to be a Linux Sys/Net Admin today, you need an understanding of both systems.
- PunchyHamster 1y agoIt is also worth mentioning TRACE target that will dump to logs which exact rule the packet hit, it's invaluable big firewalls.
- waynesonfire 1y ago> I failed to use IP tables for years. Me too, then I discovered FreeBSD and pf tables. I _feel_ like an expert network engineer now. It took time and effort of course, but the learning process "clicked" for me all along the way and I was able to build on my understandings. Give it a try! https://docs.freebsd.org/en/books/handbook/firewalls/ https://docs.freebsd.org/en/books/handbook/firewalls/ There was a recent book published on the tool, The Book of PF, 4th Edition
- jruohonen 1y agoThat's pretty cool! If someone could program a visualization tool that would generate such diagrams automatically, that would be even cooler (but likely a mission impossible).
- alhirzel 1y agoAutomatic generation would be really tough because of all the levels of abstraction traversed in this diagram in particular... But tools like Mermaid / PlantUML can get you in the ballpark, and PGF/TikZ could be a reasonable target if you want to attack that mission by generating text instead of images.
- hhutw 1y agoFor anyone who is interested, the author of this diagram also made a Linux disk I/O diagram (https://zenodo.org/records/15234151 https://zenodo.org/records/15234151). These diagrams are from his book Operativni sustavi i računalne mreže - Linux u primjeni (https://zenodo.org/records/17371946 https://zenodo.org/records/17371946) Shout out to the brilliant and generous work of the author!
- stuxnet79 1y agoThe Disk I/O diagram is excellent, thank you for sharing.
- N-Krause 1y agoDo you know if there is a English version of the book?
- hhutw 1y agoTo my knowledge, sadly I can't find an English version of it. I'm too wishing for a future English version so that I can read it. But I guess it will be a lot of work to translate it into English.
- alfanick 1y agoIf the author agrees, I could try to learn Serbo-Croatian (I'm Polish, good with languages) and translate it to English. I'm kinda a burnout Linux geek, who cannot look at computers much more. Translating a book would be fun, but I would need some sponsoring. Amadeusz at [the old name of icloud].com
- dudek1337 1y agothe book is licenced under CC BY-SA so you should be OK with translating as long as you follow the licence terms. you could try do a first pass in an AI model to translate and then proof-read it for quicker translation. good luck, it would be fun and potentially impactful ;)
- fragmede 1y ago
- roomey 1y agoI'm not sure if this takes into account para-virtualized networks on VMs, ie. VMware vm's with "virtual" hardware access It's been a few years for me tho, so perhaps it's covered with the VM section. Lovely diagram, thanks for sharing it!
- SSLy 1y agoThese usually attach in the bridge or NAT flow.
- billfruit 1y agoIs it possible we see the diagram as an svg? I am seeing it only as embedded in the pdf, and really difficult to read .
- makkes 1y agoClick on "Download" below the embedded PDF viewer and you'll get the PDF.
- rfmoz 1y agoLinux Kernel map is an other good one https://commons.wikimedia.org/wiki/File:Linux_kernel_map.png https://commons.wikimedia.org/wiki/File:Linux_kernel_map.png
- snvzz 1y agoFools admire complexity.
- 9dev 1y agoThere’s complication, and there’s complexity. Fools admire complication, engineers design solutions to complex problems. This is a diagram explaining the latter.
- KronisLV 1y agoI think it was put pretty well by describing things as accidental complexity (of which you want as little as possible) and essential complexity, which is inherent to the problem domain that you're working with and which there is no way around for. The same thing could sometimes fall into different categories as well - like going for a microservices architecture when you need to serve about 10'000 clients in total vs at some point actually needing to serve a lot of concurrent requests at any given time.
- matu3ba 1y ago> inherent to the problem domain that you're working with and which there is no way around for I'd phrase it to reasonable taken trade-offs for customer/user support and/or selling products. > going for a microservices architecture when you need to serve about 10'000 clients So far I am only aware of the use case to ship/release fast at cost of technical debt (non-synchronized master) of microservices. As I understand it, this is to a large degree due to git shortcomings and no more efficient/scalable replacement solution being in sight. Or can you explain further use cases with technical necessity?
- KronisLV 1y ago1. When you have a system where each component has significant complexity, to the point where if it was a monolith you'd have a 1M SLoC codebase that would be slow to work with - slow to compile, slow to deploy, slow to launch and would eat a lot of resources. At that point chances are that the business domain is so large that splitting up into smaller pieces wouldn't be out of the question. 2. Sometimes when you have vastly different workloads, like a bunch of parts of the system (maybe even the majority) that is just a CRUD and a small part that needs to deal with message queues, or digitally sign documents, or generate reports or do any PDF/Word/Excel/whatever processing. You could do this with a modular monolith but sometimes it's better to keep the dependencies of your project clean, especially in the case of subpar libraries that you have to use, so you at least can put all of the bullshit in one place. Also applies in cases where the load/stability of that one eccentric part is under question. 3. The tech stack might also differ a whole bunch of some of those use cases, for example if you need to process all sorts of binary data formats (e.g. satellite data) or do specific kinds of number crunching, or interact with LLMs, a lot of the time Python will be a really good solution for this, while that's not what you might be using in your stack throughout. So you might pick the right tool for the job and keep it as a separate service. 4. The good old org chart, sometimes you'll just have different teams with different approaches and will be working on different parts of the business domain - you already said that, but Conway's law is very much a thing that'd be silly to fight against all that much, because then you'd end up with an awkward monorepo, the tooling to make working which easy might just not be available to you.
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- mixedbit 1y agoFor containers you will also have own TCP/IP stack similarly to what is shown for VM on the diagram, this is done when a container uses slirp4netns to provide networking. An alternative is to use kernel TCP/IP stack, this is done when pasta is used for networking, diagram on this page shows the details:https://passt.top/passt/about/ https://passt.top/passt/about/.
- RossBencina 1y agoAny recommendations for a map of Linux user-space network management options?
- nolist_policy 1y agoqdisc is too small in this diagram and to easy to miss.
- alhirzel 1y agos/Aplication/Application/g
- phrotoma 1y agoAnyone figure out what the colour scheme means?
- PunchyHamster 1y ago*simplified. Doesn't even go into iptables/nftables
- ainiriand 1y agoIf you look closely to iptables, iptables looks back at you.
- rolandog 1y agoThanks Hrvoje Horvat for such a detailed diagram! It'll help me learn the Network stack much, much easier. His book "Operativni sustavi i računalne mreže - Linux u primjeni" [0] (Operating systems and computer networks - Linux in use) may well make learning Croatian worth it! Congrats on publishing, and thanks for such an invaluable contribution! [0]: https://zenodo.org/records/17371946 https://zenodo.org/records/17371946
- zvmaz 1y agoIncredible work! I really wish the author's book had an English translation.
- dns_snek 1y agoAre machine/AI translations viable for technical books like that [1]? It's CC-BY-SA licensed if anyone wants to give it a go. [1] https://zenodo.org/records/17371946 https://zenodo.org/records/17371946
- elcapitan 1y agoIs there some sort of equivalent to this book but in English, which explains and diagrams the Linux network stack? Doesn't need to be all in one, I feel like having a more high level overview and then subsystem diagrams with explanations would work as well.
- jaeyson 1y agoGood thing we have Hacker News