So, a customer wanted to restrict the amount of bandwidth used by his cloud server, with a kind of self-QOS like service.

To do this is actually quite simple, wondershaper is the magic wand for you.

# Install
apt-get install wondershaper 
# or
yum install wondershaper

#Configure for interface
sudo wondershaper eth1 256 128  

(Values are in kbit, so be sure to remember!)

If this isn’t suitable for you and you want something to restrict user space, like applications, then use trickle.

$ trickle -u {up} -d {down} {program}  

i.e. for restricting firefox to 8Kb/s up and down use:

    $ trickle -u 8 -d 8 firefox