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Entire Linux Network stack diagram (2024)

elevation

This 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!

Koffiepoeder

Can you share the diagram? Would love to become iptables-enlightened.

elevation

Eventually I used more detailed diagrams, but this one was like a lightbulb going off:

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.

jcynix

Besides the diagram you'll find tutorials on https://www.frozentux.net/category/linux/iptables/ too.

And at http://www.easyfwgen.morizot.net/ there's an old, but still useful generator for an iptables setup. That should help to understand iptables.

eptcyka

It is time to be nftables enlightened instead.

hhutw

For anyone who is interested, the author of this diagram also made a Linux disk I/O diagram (https://zenodo.org/records/15234151). These diagrams are from his book Operativni sustavi i računalne mreže - Linux u primjeni (https://zenodo.org/records/17371946)

Shout out to the brilliant and generous work of the author!

N-Krause

Do you know if there is a English version of the book?

hhutw

To 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.

jruohonen

That'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).

roomey

I'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!

snvzz

Fools admire complexity.

billfruit

Is it possible we see the diagram as an svg? I am seeing it only as embedded in the pdf, and really difficult to read .

colordrops

I'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.