very simple port scanner in ruby

portscan.rb

require 'socket' #socket library

def open_port(host, port)
  sock = Socket.new(:INET, :STREAM)
  raw = Socket.sockaddr_in(port, host)
  puts "#{port} open." if sock.connect(raw)
rescue (Errno::ECONNREFUSED)
  rescue(Errno::ETIMEDOUT)
end

def main(host, start_port, end_port)
  until start_port == end_port do
    open_port(host, start_port)
    start_port += 1
  end
end

main ARGV[0], ARGV[1].to_i, ARGV[2].to_i