tc-con: Manipulate Linux Kernel netem for simulation of high latency, low bandwidth, and high packet loss networks.

tc-con

#!/bin/bash
#
# Script to reduce bandwidth rate and create network delay and packet loss on linux interfaces
# Can be placed on one interface (one server) or both interfaces (both servers).
#
# Simply run ./tc-con start to start it
# and ./tc-con stop to stop it.
# Run ./tc-con status to see if it's running.
#
#  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
#
# Originally from iplocation.net/traffic-control
# Further information at http://www.linuxfoundation.org/collaborate/workgroups/networking/netem
# Updated by Jon Drews (jondrews.com)

# Name of the traffic control command.
TC=/sbin/tc

# The network interface we're planning on limiting bandwidth.
IF=eth2

# Rate (both ways)
RATE=100kbit

# Delay amount
DELAY=250ms

# Amount of delay variance (+/-)
DELAY_VARIANCE=50ms

# Packet loss amount
PACKET_LOSS=10%

# Packet loss variance
PACKET_LOSS_VARIANCE=5%

# Enable packet loss
#PACKET_LOSS_ENABLED=TRUE
PACKET_LOSS_ENABLED=FALSE

start() {

    # Apply rate limits
    $TC qdisc add dev $IF root handle 1: tbf rate $RATE buffer 1600 limit 3000

    if [[ $PACKET_LOSS_ENABLED != TRUE ]]
    then
        # Apply delay with variance, and packet loss
        $TC qdisc add dev $IF parent 1:1 handle 10: netem delay $DELAY $DELAY_VARIANCE distribution normal
    else
        # Apply delay with variance, and packet loss with variance
        $TC qdisc add dev $IF parent 1:1 handle 10: netem delay $DELAY $DELAY_VARIANCE distribution normal loss $PACKET_LOSS $PACKET_LOSS_VARIANCE
    fi

}

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: "
    restart
    echo "done"
    ;;

  show)

    echo "Bandwidth shaping status for $IF:"
    show
    echo ""
    ;;

  status)

    echo "Bandwidth shaping status for $IF:"
    show
    echo ""
    ;;

  *)

    pwd=$(pwd)
    echo "Usage: tc.bash {start|stop|restart|show|status}"
    ;;

esac

exit 0