iperf3 is in kali linux repositories (and in debain, ubuntu, arch etc...) and works like a charm, very easy to use.
Code:
apt show iperf3
Package: iperf3
Version: 3.1.3-1
Priority: optional
Section: net
Maintainer: Raoul Gunnar Borenius <[email protected]>
Installed-Size: 41,0 kB
Depends: libc6 (>= 2.11), libiperf0
Homepage: http://software.es.net/iperf/
Download-Size: 18,4 kB
APT-Manual-Installed: yes
APT-Sources: http://http.kali.org/kali kali-rolling/main amd64 Packages
Description: Internet Protocol bandwidth measuring tool
Iperf3 is a tool for performing network throughput measurements. It can
test either TCP or UDP throughput.
.
This is a new implementation that shares no code with the original
iperf from NLANR/DAST and also is not backwards compatible.
.
This package contains the command line utility.
There are also versions for mac and windows so you can use it in a multi-system environment