#!/bin/bash
#  tc uses the following units when passed as a parameter.
#  kbps: Kilobytes per second
#  mbps: Megabytes per second
#  kbit: Kilobits per second
#  mbit: Megabits per second
#  bps: Bytes per second
#       Amounts of data can be specified in:
#       kb or k: Kilobytes
#       mb or m: Megabytes
#       mbit: Megabits
#       kbit: Kilobits
#  To get the byte figure from bits, divide the number by 8 bit
#

TC=/sbin/tc
IF=eth0

# Download and Upload Bandwidth
DNLD=10mbit
UPLD=10mbit
LATENCY=50ms

# Destination Host
IP=128.2.213.24

# Filter options for limiting the intended interface.
U32="$TC filter add dev $IF protocol ip parent 1:0 prio 1 u32"

start() {
# We'll use Hierarchical Token Bucket (HTB) to shape bandwidth.
# For detailed configuration options, please consult Linux man
# page.
    $TC qdisc add dev $IF root handle 1: htb default 30
    $TC class add dev $IF parent 1: classid 1:1 htb rate $DNLD
    $TC class add dev $IF parent 1: classid 1:2 htb rate $UPLD
	$TC qdisc add dev $IF parent 1:1 handle 10: netem delay $LATENCY
	$TC qdisc add dev $IF parent 1:2 handle 20: netem delay $LATENCY
    $U32 match ip dst $IP/32 flowid 1:1
    $U32 match ip src $IP/32 flowid 1:2
# The first line creates the root qdisc, and the next two lines
# create two child qdisc that are to be used to shape download
# and upload bandwidth.
#
# The 4th and 5th line creates the filter to match the interface.
# The 'dst' IP address is used to limit download speed, and the
# 'src' IP address is used to limit upload speed.
}

stop() {
# Stop the bandwidth shaping.
    $TC qdisc del dev $IF root
}

restart() {
# Self-explanatory.
    stop
    sleep 1
    start
}

show() {
# Display status of traffic control status.
    $TC -s qdisc ls dev $IF
}


case "$1" in
  start)
    echo -n "Starting bandwidth shaping: "
    start
    echo "done"
    ;;
  stop)
    echo -n "Stopping bandwidth shaping: "
    stop
    echo "done"
    ;;
  restart)
    echo -n "Restarting bandwidth shaping: "
    if [ "$#" -ne 2 ]; then
        echo "Illegal number of parameters"
        echo "Usage: tc.bash restart bw(mbps)"
        exit 1
    fi

    DNLD=$2mbit
    UPLD=$2mbit
    echo "Network throughput: $2 Mbps"
    restart
    echo "done"
    ;;
  show)
    echo "Bandwidth shaping status for $IF:"
    show
    echo ""
    ;;
  *)
    pwd=$(pwd)
    echo "Usage: tc.bash {start|stop|restart|show}"
    ;;
esac

exit 0