TC Rate limiting

ratelimit.sh

#!/bin/bash
# vim: ts=2 sw=2 et ai tw=80
################################################################################
# Script designed to shape system bandwidth usage based on the very fine
# reference found https://www.iplocation.net/traffic-control
################################################################################
set -e

# -- CONSTANTS
TC=/sbin/tc
IF=em1
LIMIT_I=95mbit  # download rate
LIMIT_O=95mbit  # upload rate

# Filter options for limiting the intended interface.
U32="$TC filter add dev $IF protocol ip parent 1:0 prio 1 u32"

# WARNING: If the device order ever changes, this could cause problems
ME=$(hostname -I  | cut -f1 -d ' ')

# -- METHODS
checkDeviceValid() {
  local block="(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)"
  local regex="${block}\.${block}\.${block}\.${block}"
  local count=$(ip addr show ${IF} |
                  grep ${ME} 2> /dev/null |
                    grep -c -E -o ${regex})

  if [ ${count} -eq 0 ]
  then
    return 1
  else
    return 0
  fi
}

start() {
  echo "Starting"
  ${TC} qdisc add dev ${IF} root handle 1: htb default 30
  ${TC} class add dev ${IF} parent 1: classid 1:1 htb rate ${LIMIT_I}
  ${TC} class add dev ${IF} parent 1: classid 1:2 htb rate ${LIMIT_O}
  ${U32} match ip dst ${ME}/32 flowid 1:1
  ${U32} match ip src ${ME}/32 flowid 1:2
}

stop() {
  echo "Stopping"
  ${TC} qdisc del dev ${IF} root
}

printUsage() {
  echo "Usage: $0 {start|stop}"
  exit 1
}

# -- MAIN
action=$1
if [ -z ${action} ]
then
  printUsage
fi

if ! checkDeviceValid
then
  echo "Invalid network device: ${IF}"
  exit 1
fi

echo "Configuring ${IF} with IP ${ME}"

case ${action} in
  start)
    start
    ;;
  stop)
    stop
    ;;
  *)
    printUsage
    ;;
esac

echo "Done"