RE: Scanning--more then one side to the argument

["Steve Fletcher" <safletcher () insightbb com>]

That would depend on the port and what function it serves.  For example, you
might show port 25 as open because they have an SMTP server and it is not
behind a firewall.

Here is a definition of the different states, straight from the nmap man
page:

        "The state is either "open", "filtered", or "unfiltered".  Open
means   that       the target machine will accept() connections on that
port.   Filtered means that a firewall, filter, or other network obstacle is
covering the port and preventing nmap from determining whether the      port
is open.  Unfiltered means that the port is known by nmap to  be
closed  and  no firewall/filter seems to be interfering with nmap's
attempts to determine this.  Unfiltered ports are the common case and   are
only shown when most of the scanned ports are in the filtered   state."

Hope this helps.

Steve Fletcher
MCSE (NT4/Win2k), MCSE: Security (Win2k), HP Master ASE, CCNA, Security+
safletcher () insightbb com

-----Original Message-----
From: Shand [mailto:shand () adelphia net] 
Sent: Wednesday, March 30, 2005 2:33 PM
To: Steve Fletcher; security-basics () securityfocus com
Subject: Re: Scanning--more then one side to the argument

External scans.

Against customer using our internet service.

Does a port have to show as "open" or can they for usability show only as 
filtered, closed?

Thoughts?

Shand




----- Original Message ----- 
From: "Steve Fletcher" <safletcher () insightbb com>
To: "'Sherman Hand'" <shand () adelphia net>; 
<security-basics () securityfocus com>
Sent: Wednesday, March 30, 2005 3:18 PM
Subject: RE: Scanning--more then one side to the argument


> I have a question regarding this.  Are you talking about doing an external
> scan or an internal scan?  I assume an external, because an internal scan
> should show a LOT of open ports.
>
> I would say that any open port POTENTIALLY could be a security issue 
> waiting
> to happen, but common sense dictates that some ports must be open for
> usability reasons.  Plus, if you're going to follow this line of thought,
> the fact that the systems are connected to the Internet AT ALL poses a
> potential risk.  Or, just being networked could be a risk.  Or, being
> powered on poses a potential risk.
>
> So, based on this, sure it COULD be a security risk waiting to happen, but
> more information needs to be gathered to determine the true extent of the
> risk.  And, it must be reevaluated at regular intervals to catch new 
> issues
> that might have come up since the last scan.  What is safe now might not 
> be
> 6 months from now.
>
> Hope this helps.
>
> Steve Fletcher
> MCSE (NT4/Win2k), MCSE: Security (Win2k), HP Master ASE, CCNA, Security+
> safletcher () insightbb com
>
> -----Original Message-----
> From: Sherman Hand [mailto:shand () adelphia net]
> Sent: Wednesday, March 30, 2005 5:05 PM
> To: security-basics () securityfocus com
> Subject: Scanning--more then one side to the argument
>
>
>
> There has been a on going discussion about the scanning results on our
> customers.
>
> Thought one says that "any" port on a standard nmap, showing as "open" is 
> a
> security risk.
>
> Thought two says, no since some things need to show in a state of open.
>
> Should we be stating that through proactive scan, when we find any port
> showing as open, that it is a security issue waiting to happen?
>
> Or only if we can show a issue?
>
> Thoughts?
>
> Shand



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