nmap root vs user question

Hi All,

"#" is my "root" prompt and "$" is my user prompt.

Question: why does namp sometimes work as root
and not as a user?  Why no warning that a command
has to be run as root?


This works as root:
      # nmap -p T:5020,5900 192.168.202.210
      Starting Nmap 6.40 ( http://nmap.org ) at 2013-10-04 14:25 PDT
      Nmap scan report for 192.168.202.210
      Host is up (0.00063s latency).
      PORT     STATE    SERVICE
      5020/tcp filtered zenginkyo-1
      5900/tcp filtered vnc

Same command does not work as a user:
      $ nmap  -p T:5020,5900 192.168.202.210
      Starting Nmap 6.40 ( http://nmap.org ) at 2013-10-04 14:25 PDT
      Note: Host seems down. If it is really up, but blocking our
            ping probes, try -Pn


Many thanks,
-T

-- 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Computers are like air conditioners.
They malfunction when you open windows
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


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