limiting bandwidth per user

Over the last few months i have been running a TC script to control the bandwidth consumed per IP. It has worked remarkably well so far so i thought i would share what i have been using. You will need to make sure that your system has TC installed, any modern Linux flavour should have this. I run my PMS on centos 6.6 and the script worked out the box with only a few mods needed to make it work, these are reflected in the script posted below. Copy the script below and save it as a shell script on your system, name is unimportant, just make sure permissions are correct.

#!/bin/bash
NETCARD=eth0
MAXBANDWIDTH=1000000

# reinit
tc qdisc del dev $NETCARD root handle 1
tc qdisc add dev $NETCARD root handle 1: htb default 9999

# create the default class
tc class add dev $NETCARD parent 1:0 classid 1:9999 htb rate $(( $MAXBANDWIDTH ))kbit ceil $(( $MAXBANDWIDTH ))kbit burst 100k prio 9999

# control bandwidth per IP
declare -A ipctrl
# define list of IP and bandwidth (in kilo bits per seconds) below
ipctrl[IP ADDRESS OF USER HERE]="MAX Kb PER IP HERE"

mark=0
for ip in "${!ipctrl[@]}"
do
    mark=$(( mark + 1 ))
    bandwidth=${ipctrl[$ip]}

    # traffic shaping rule
    tc class add dev $NETCARD parent 1:0 classid 1:$mark htb rate $(( $bandwidth ))kbit ceil $(( $bandwidth ))kbit burst 3kbit prio $mark
    #tc class add dev $NETCARD parent 1:0 classid 1:$mark htb rate 2048kbit ceil 2048kbit burst 3kbit prio $mark

    # netfilter packet marking rule
    iptables -t mangle -A INPUT -i $NETCARD -s $ip -j CONNMARK --set-mark $mark

    # filter that bind the two
    tc filter add dev $NETCARD parent 1:0 protocol ip prio $mark handle $mark fw flowid 1:$mark

    echo "IP $ip is attached to mark $mark and limited to $bandwidth kbps"
done

#propagate netfilter marks on connections
iptables -t mangle -A POSTROUTING -j CONNMARK --restore-mark

change NETCARD to the interface name of your nic that PMS is served through
change MAXBANDWIDTH to the interface speed of you NIC from above

starting at line 15 enter your users ip addresses you want to limit as an example the line/s would look like this, inside the brackets in the users ip address, in the double quotes enter their max bandwidth in Kb.
ipctrl[127.0.0.1]="1536" # limit this user to 1.5Mb
ipctrl[127.0.0.2]="2048" # limit this user to 2Mb

after entering your users IP addresses execute the script, in the future after making changes to users just re-execute the script. After this you can verify it's working by using IFTOP.