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Re: Looking for specific information on 'how' nessus discovers ports

Subject: Re: Looking for specific information on 'how' nessus discovers ports
Date: Fri, 14 Sep 2007 12:22:33 +0200
On Thu, 13 Sep 2007 12:03:59 -0500
"Eric Whitehill" <EWhitehill@eidebailly.com> wrote:

Basically I'm trying to figure out how Nessus determines a host is
'alive'

By sending miscellaneous packets and waiting for an answer.
The ping_host plugin can do ARP (on the same physical network only),
"TCP ping" (with SYN packets on common or chosen ports), classic ICMP
ping, or "UDP ping" (by sending a couple of requests like DNS or RPC)

and then if it is alive, how does it determine if a port is open or not. 

Then it runs a portscanner. That's rather common.

It's not for me, it's for a vendor that is being rather 'difficult'.  

???
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