Created
April 30, 2015 16:04
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#!/bin/bash | |
# This uses linux "transport control" aka tc to affect OUTGOING packets. | |
# For more information about "netem", the network emulation module, see: | |
# http://www.linuxfoundation.org/collaborate/workgroups/networking/netem | |
# http://lartc.org/howto/index.html section 9 and 12. | |
usage() { | |
echo "USAGE: $(basename $0) --interface=<ethX> (--dport=<PORT> | --host=<IP>) (--delay=<DELAY_SPEC> | --loss=<LOSS_SPEC>) --start" | |
echo " $(basename $0) --interface=<ethX> (--stop | --status)" | |
echo " DELAY_SPEC examples: '1000ms', '100ms 10ms', '3000ms 2000ms distribution normal'" | |
echo " LOSS_SPEC examples: '2%'" | |
exit 1 | |
} | |
port="" | |
delay="" | |
loss="" | |
dev="lo" | |
host="" | |
while [ $# -gt 0 ]; do | |
param=${1%%=*} | |
value=${1#*=} | |
case $param in | |
--dport) | |
port="dport $value 0xffff" | |
;; | |
--host) | |
host="dst $value" | |
;; | |
--delay) | |
delay=$value | |
;; | |
--loss) | |
loss="random $value" | |
;; | |
--interface) | |
dev=$value | |
;; | |
--start) | |
START=1 | |
;; | |
--stop) | |
STOP=1 | |
;; | |
--status) | |
STATUS=1 | |
;; | |
--help | -h) | |
usage | |
;; | |
*) | |
echo "ERROR: bad argument '$1'" | |
usage | |
;; | |
esac | |
shift | |
done | |
if [ -n "$host" ] && [ -n "$port" ]; then | |
echo "ERROR: you can only use --host or --dport, not both" | |
usage | |
fi | |
if [ $(expr ${START:-0} + ${STOP:-0} + ${STATUS:-0}) != 1 ] ; then | |
echo "ERROR: use exactly one of --start --stop --status" | |
usage | |
fi | |
if [ -n "$STATUS" ]; then | |
/sbin/tc -s qdisc | |
/sbin/tc filter show dev $dev | |
fi | |
if [ -n "$START" ]; then | |
echo "affecting outgoing to $host $port on interface $dev - delay='$delay' loss='$loss'" | |
/sbin/tc qdisc del dev $dev root 2>/dev/null | |
/sbin/tc qdisc add dev $dev root handle 1: prio | |
/sbin/tc filter add dev $dev protocol ip parent 1: prio 1 u32 match ip $host $port flowid 1:3 | |
/sbin/tc qdisc add dev $dev parent 1:3 handle 31: netem ${delay:+delay $delay} ${loss:+loss $loss} | |
fi | |
if [ -n "$STOP" ]; then | |
/sbin/tc qdisc del dev $dev root | |
fi |
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