title: Python nmap not showing hosts
body: <p>This is the code:</p>
  <pre><code>import nmap
  # initialize the port scanner
  nmScan = nmap.PortScanner()
  
  # scan localhost for ports in range 21-443
  nmScan.scan('89.43.3.92', '20-450')
  
  # run a loop to print all the found result about the ports
  print(nmScan.all_hosts())
  for host in nmScan.all_hosts():
       print('Host : %s (%s)' % (host, nmScan[host].hostname()))
       print('State : %s' % nmScan[host].state())
       for proto in nmScan[host].all_protocols():
           print('----------')
           print('Protocol : %s' % proto)
   
           lport = nmScan[host][proto].keys()
          #  lport.sort()
           for port in lport:
               print ('port : %s\service : %s' % (port, nmScan[host][proto][port]['name']))
  </code></pre>
  <p>When I use 127.0.0.1, the code works fine and <code>nmScan.all_hosts()</code> is not empty, but when I check other ip addresses, it always is empty.</p>
  <p>P.S: In the code above, I'm trying to see what service each port is running.</p>