Re: probe for unspecified port

[MadHat <madhat () unspecific com>]

On Mar 6, 2004, at 11:50 AM, testic wrote:
> > Why is this command
> >  nmap.exe -v -sS -p21 -O pcgv2
>
> > sending a ping and probes to port 80 and 21?
> > I didn't specify port 80. What did I miss?
>
> I would imagine that Nmaps default behaviour is to "TCP ping" a host 
> before
> scanning to determine whether or not the host is up. If you dont want 
> this
> behaviour use the -P0 switch to not ping at all.

You are correct for the reason.  You could also do a -PS21 saying to 
use a TCP SYN for the PING on port 21.  It will see that the port is 
open from the initial SYN and not duplicate it.

Word of Warning: Scanning for one port and using -O will not be very 
accurate at all.  For an accurate scan you need an open and a closed 
port.


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