Quick & naive upload traffic limit

quick-tc.rb

#!/usr/bin/env ruby
# quick egress traffic limit for linux
# Usage: $0 dev kbps

MIN_RATE = 512

devs = []
rate = 0

dev_names = Dir['/sys/devices/**/net/*'].map{|x|File.basename(x)}

ARGV.each do |v|
  if dev_names.include? v
    devs.push v
  else
    rate = v.to_i
  end
end

rate = MIN_RATE if rate < MIN_RATE && rate >= 0
if devs.empty?
  puts "Usage: #$0 [dev1] [dev2] [kbps=#{MIN_RATE}]"
  puts "       #$0 eth0          # limit eth0 upload speed to #{MIN_RATE}kbps"
  puts "       #$0 eth0 eth1 256 # limit eth0 and eth1 upload speed to 256kbps"
  puts "       #$0 eth0 -1       # unlimit eth0 upload speed"
end

sudo_prefix = Process.uid == 0 ? '' : 'sudo '

devs.each do |dev|
  system "#{sudo_prefix} tc qdisc del dev #{dev} root >/dev/null 2>/dev/null"
  if rate < 0
    puts "Unlimit #{dev}"
  else
    puts "Limit #{dev} to #{rate}kbps"
    system "#{sudo_prefix} tc qdisc add dev #{dev} root tbf rate #{rate}kbit latency 500ms burst #{rate * 3 / 2}kbit"
  end
end