#!/usr/bin/env bash
# th(at)bogus.net
# the interfaces you defined in badlink.sh
INTERFACES="ens18 ens19"
for i in $INTERFACES
do
        tc qdisc del dev $i root
done
root@wanem:~# cat badlink.sh 
#!/usr/bin/env bash
# th(at)bogus.net
# most of this was borrowed from
# https://wiki.linuxfoundation.org/networking/netem

# the interfaces on which you want this traffic shaping 
INTERFACES="ens18 ens19" 

# WAN link parameters (VSAT links typically have between 550-650ms latency)
# DELAY_MS should be half, as we do traffic control on ingress and egress interfaces
DELAY_MS=275
RATE_MBIT=0.5
LOSS_PC=15
DUPLICATE_PC=5
CORRUPT_PC=1

if [ $(which bc) = "" ]
then
        echo "error: bc required, on debian, run apt -y install bc"
        exit 1
fi

BUF_PKTS=100
BDP_BYTES=$(echo "($DELAY_MS/1000.0)*($RATE_MBIT*1000000.0/8.0)" | bc -q -l)
BDP_PKTS=$(echo "$BDP_BYTES/1500" | bc -q)
LIMIT_PKTS=$(echo "$BDP_PKTS+$BUF_PKTS" | bc -q)

for i in $INTERFACES
do
        tc qdisc add dev $i root netem delay 100ms
        tc qdisc replace dev $i root netem delay ${DELAY_MS}ms rate ${RATE_MBIT}Mbit limit ${LIMIT_PKTS}
        tc qdisc change dev $i root netem delay ${DELAY_MS}ms 40ms 25% loss ${LOSS_PC}% 25% duplicate ${DUPLICATE_PC}% corrupt ${CORRUPT_PC}%
done