netemu

#!/bin/busybox ash
IFACE=eth0
DELAY=0
LOSS=0

flush_tc() {
    tc qdisc del dev $IFACE root 2> /dev/null > /dev/null
}

usage() {
cat << EOF
USAGE: $0 [-i <iface>] [-u <upload_rate>] [-d <delay>] [-l <packet_loss_percent>]
       $0 [-i <iface>] status
       $0 [-i <iface>] stop

       default iface is $IFACE

EXAMPLE: $0 -i eth0 -u 256kbit -d 100ms -l 10%
EOF
exit 1
}

if [ $# -eq 0 ]; then usage; fi

GETOPT=`getopt -o i:u:d:l: -- "$@"`
if [ $? != 0 ]; then usage; fi
eval set -- "$GETOPT"

while true; do
    case $1 in
        -i) IFACE=$2; shift 2;;
        -u) UPLOAD=$2; shift 2;;
        -d) DELAY=$2; shift 2;;
        -l) LOSS=$2; shift 2;;
        --) shift; break;;
    esac
done

if [ x"$1" = x"stop" ]; then
    flush_tc
    exit
elif [ x"$1" = x"status" ]; then
    tc -s qdisc ls dev $IFACE
    tc -s class ls dev $IFACE
    exit
fi

flush_tc
tc qdisc add dev $IFACE root handle 1:0 netem delay $DELAY loss $LOSS
if [ x"$UPLOAD" != x ]; then
    tc qdisc add dev $IFACE parent 1:1 handle 10: tbf rate $UPLOAD buffer 1600 limit 3000
fi