Description:

  This tool checks if a host is up. It's done sending a probe packet and
  expecting a reply.
  This tool sends an UDP packet to a computer. If host permits UDP, it
  will send back an ICMP error (if port is closed), or send back nothing
  (if port is open). So, it's important to understand UDP port has to be
  closed for computer to return something.
  Parameter --spoofip indicates how to generate link layer for spoofing.
  Values 'best', 'link' or 'raw' are common choices for --spoofip. Here
  is the list of accepted values:
   - 'raw' means to spoof at IP4/IP6 level (it uses system IP stack). If
     a firewall is installed, or on some systems, this might not work.
   - 'linkf' means to spoof at link level (currently, only Ethernet is
     supported). The 'f' means to Fill source Ethernet address.
     However, if source IP address is spoofed, it might be impossible
     to Fill it. So, linkf will not work: use linkb or linkfb instead.
   - 'linkb' means to spoof at link level. The 'b' means to left a Blank
     source Ethernet address (0:0:0:0:0:0, do not try to Fill it).
   - 'linkfb' means to spoof at link level. The 'f' means to try to Fill
     source Ethernet address, but if it is not possible, it is left
     Blank.
   - 'rawlinkf' means to try 'raw', then try 'linkf'
   - 'rawlinkb' means to try 'raw', then try 'linkb'
   - 'rawlinkfb' means to try 'raw', then try 'linkfb'
   - 'linkfraw' means to try 'linkf', then try 'raw'
   - 'linkbraw' means to try 'linkb', then try 'raw'
   - 'linkfbraw' means to try 'linkfb', then try 'raw'
   - 'link' is an alias for 'linkfb'
   - 'rawlink' is an alias for 'rawlinkfb'
   - 'linkraw' is an alias for 'linkfbraw'
   - 'best' is an alias for 'linkraw'. It should work in all cases.
  
  This tool may need to be run with admin privilege in order to sniff
  and spoof.
   

Usage:

Parameters:

Examples: