hinder.sh

#!/bin/bash

set -e

function printUsage() {
  echo -e USAGE="\nUsage: $0 ip_address delay_in_ms percentage_of_packet_loss \nor\nUsage: $0 reset\n"
}

if [ "$#" == "0" ] || [ "$#" == "1" ] && [ "$1" != "reset" ] || [ "$1" != "reset" ] && [ "$#" -ne 3 ]; then
  printUsage
  exit 1
fi

IP=$1
DELAY=$2
PACKET_LOSS=$(echo "scale=1;10/100" | bc -l)

if [ "$IP" = "reset" ]; then
  printf 'Resetting... '
  sudo ipfw list | grep 'pipe' | awk '{print $1}' | while read name; do sudo ipfw delete $name ; done
  echo 'Done'
else
  echo "Creating rules to simulate latency to ${IP}... "

  # Create 2 pipes and assigned traffic to and from our webserver to each:
  sudo ipfw add pipe 1 ip from any to $IP
  sudo ipfw add pipe 2 ip from $IP to any

  # Configure the pipes we just created:
  sudo ipfw pipe 1 config delay ${DELAY}ms bw 1Mbit/s plr $PACKET_LOSS
  sudo ipfw pipe 2 config delay ${DELAY}ms bw 1Mbit/s plr $PACKET_LOSS

  echo "Done"
fi