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!

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!

Linux Kernel map is an other good one https://commons.wikimedia.org/wiki/File:Linux_kernel_map.png

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).

*simplified.

Doesn't even go into iptables/nftables

For 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/.

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 .

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.

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!

Anyone figure out what the colour scheme means?

Any recommendations for a map of Linux user-space network management options?

s/Aplication/Application/g

qdisc is too small in this diagram and to easy to miss.

wow

Fools admire complexity.