Save the following script in a file called speed_test
#!/bin/bash
# Requirements
# sudo apt-get install lftp iperf
lftp -e 'pget http://releases.ubuntu.com/14.04.3/ubuntu-14.04.3-desktop-amd64.iso; exit; '
make sure the file is executable: sudo chmod +x speed_test
Once you have installed lftp and iperf make sure you have the script somewhere in your $PATH.
The script basically downloads an ubuntu iso and does the math.
The output looks like this on a AWS m3.large instance:
$ speed_test
1054871586 bytes transferred in 14 seconds (70.37M/s)
Multiply by 8 to convert 70.37M/s to Megabits per second = 562.96 Mbit/s
AWS’s download speeds for m3.large instances is half a gigabit in January 2016. (or is that the upload speed of the Ubuntu ISO server?)