#!/bin/bash

# configuration
host="twitter.com"

# usage
if [ "$*" == "" ]; then
	echo "usage: $0 [off|fast|medium|slow]"
	exit
fi

# remove any previous firewall rules
sudo ipfw list 10 > /dev/null 2>&1
if [ $? -eq 0 ]; then
	sudo ipfw delete 10 > /dev/null 2>&1
fi
sudo ipfw list 11 > /dev/null 2>&1
if [ $? -eq 0 ]; then
	sudo ipfw delete 11 > /dev/null 2>&1
fi

# process the command line option
if [ "$1" == "off" ]; then
	# add rules to deny any connections to configured host
	sudo ipfw add 10 deny tcp from $host to me
	sudo ipfw add 11 deny tcp from me to $host
else
	# create a pipe with limited bandwidth
	bandwidth="100Kbit"
	if [ "$1" == "fast" ]; then
		bandwidth="300Kbit"
	elif [ "$1" == "slow" ]; then
		bandwidth="10Kbit"
	fi
	sudo ipfw pipe 1 config bw $bandwidth

	# add rules to use bandwidth limited pipe 
	sudo ipfw add 10 pipe 1 tcp from $host to me
	sudo ipfw add 11 pipe 1 tcp from me to $host
fi