Re: TCP torture testing

[Lukas Tribus <lukas () ltri eu>]

Hello,

On Fri, 17 Jan 2025 at 19:13, Brandon Martin <lists.nanog () monmotha net> wrote:
> Does anyone know of a good way to simulate oddball TCP happenings like:
>
> * Out of order delivery
> * Variable delivery delays

I would suggest to take a look at linux tc-netem


> * (Especially) Unusual segmentation e.g. splitting part of a stream that
> would and should normally be sent in a single segment into several
> smaller segments sent back-to-back
>
> And especially doing so with traffic from an existing TCP-speaking
> application i.e. something like a TCP proxy that lets you deliberately
> mess with the segmentation and delivery order.

This is more difficult because a TCP proxy (as in a userspace
application) does not do the TCP segmenting, the kernel does. Sure the
application may set flags like TCP_NODELAY to toggle Nagle, but beyond
that the application has not really control over TCP segmentation. So
a tool like this would basically need to reimplement TCP in userspace.

Not sure something like this is out there.


Lukas