OSEC

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Re: TR: Mapping Class A network ( any easy trick?)

From: James Riden (j.ridenmassey.ac.nz)
Date: Mon Feb 21 2005 - 21:05:00 CST

Vicente Feito <vicente.feitogmail.com> writes:

> I keep reading the same mistake over and over, not talking about this
> particular message, but about something most admins do, they start flooding
> the network with nmap and trying to do a broadcast scan, that's insane, they
> do nmap -sS -p1-65535 x.x.x.x/24 or something like that, I don't mean to
> critizice, but I'm my opinion, what I do if I need something like this, is
> first, just find out what hosts are up, something like nmap -sP <whatever>

I believe that nmap does ping before doing the SYN scan by default, so
it won't generate thousands of SYNs for hosts which aren't up.

-P0 Do not try to ping hosts at all before scanning them.
       [snip]
       By default, Nmap sends an ICMP echo request and a TCP ACK packet to
       port 80.

--
James Riden / j.ridenmassey.ac.nz / Systems Security Engineer
GPG public key available at: http://www.massey.ac.nz/~jriden/
This post does not necessarily represent the views of my employer.