RE: verifying an open or closed port on an ip address

["Simon" <simon () snosoft com>]

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I love it when people respond with these sorts of e-mails. I think
the question is will a port accept a connection, and yes, you can
determine that FOR THE MOST PART from a remote location. Answering
such a simple question with such a low-level answer is a failed
attempt at flaunting your knowledge. Don't try to sound so smart,
instead try to give him help.

- -----Original Message-----
From: Jason Coombs [mailto:jasonc () science org]
Sent: Thursday, August 07, 2003 5:07 PM
To: ian () kingcon com; security-basics () securityfocus com
Subject: RE: verifying an open or closed port on an ip address


you can't determine conclusively whether a port is 'open' from a
remote
location. what actions does your CPU take when bits arrive on an
exposed
network interface? If you don't know, then you can't tell whether a
port is
open. judging a port to be 'open' because it responds to the TCP
3-way
handshake and 'closed' otherwise is wrong, even if you only care
about TCP and
ignore UDP.

- -----Original Message-----
From: ian () kingcon com [mailto:ian () kingcon com]
Sent: Thursday, August 07, 2003 7:45 AM
To: security-basics () securityfocus com
Subject: verifying an open or closed port on an ip address


Hello,

I am looking for a windows compatible utility or method, preferably
command
line, where I can verify whether a port on an ip address is reachable
or not.
I want to be able to do individual ports and not port scans.  Say for
instance
I wish to verify that port 677 is closed to traffic on ip address Ex.
172.16.0.1, I'm looking for a utility that would do something like:

Check 172.16.0.1 port 677

and tell me whether that port was reachable.

So if I have two networks and I use this command from one I can
determine
whether a port is reachable on another.  To determine whether a
security
measure is failing or not.

There may be a simple way to do this...

Thanks
Ian
:)



Go to www.missingkids.com

But give an' take's the gospel, an' we'll call the bargain fair,
For if you 'ave lost more than us, you crumpled up the square!

Mowgli's real Father...


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