Home page logo

basics logo Security Basics mailing list archives

RE: Port-Knocking vulnerabilities?
From: "Jay" <jay.tomas () infosecguru com>
Date: Mon, 31 Dec 2007 12:31:01 -0500

You obviously haven't looked into the technology and don't understand basic concepts of authentication.

Lets review - Authentication - proving you are who you say your are.

1)Something you know - password, pin number, sequence of agreed upon ports to knock before a separate service starts to 
listen to furter authenicate or authorize access to server.

2)Something you are - fingerprint, retina scan, DNA.

3)Something you have - keyfob, certificate.

Like any technique, it is merely 1 layer of the defense. It can be implemented in a weak way that provides little to no 
defense or more complex way effectively adding to the layers of defense.

I know you will respond to this please keep it to under 3 pages. You aren't going to change my mind or understanding of 
basic security concepts. I posted this for the benefit of those on the list that are truly trying to learn security 


----- Original Message -----
From: Craig Wright [mailto:Craig.Wright () bdo com au]
To: tomc () targetbilling com,kappaalphapieta () hotmail com
Cc: security-basics () securityfocus com
Sent: Sat, 29 Dec 2007 06:48:50 +1100
Subject: RE: Port-Knocking vulnerabilities?

Port Knocking is obfuscation and not a security technique. It was and is designed not as a security function, but as a 
channel to hide communications on compromised hosts.

It is a hacker toy and not a security tool. It is as effective as turning on the ?IP Security? flags in a packet (just 
use hping and away you go).

Dr Craig Wright (GSE-Compliance)

Craig Wright
Manager of Information Systems

Direct : +61 2 9286 5497
Craig.Wright () bdo com au
+61 417 683 914

BDO Kendalls (NSW)
Level 19, 2 Market Street Sydney NSW 2000
GPO BOX 2551 Sydney NSW 2001
Fax +61 2 9993 9497

Liability limited by a scheme approved under Professional Standards Legislation in respect of matters arising within 
those States and Territories of Australia where such legislation exists.

The information in this email and any attachments is confidential.  If you are not the named addressee you must not 
read, print, copy, distribute, or use in any way this transmission or any information it contains.  If you have 
received this message in error, please notify the sender by return email, destroy all copies and delete it from your 

Any views expressed in this message are those of the individual sender and not necessarily endorsed by BDO Kendalls.  
You may not rely on this message as advice unless subsequently confirmed by fax or letter signed by a Partner or 
Director of BDO Kendalls.  It is your responsibility to scan this communication and any files attached for computer 
viruses and other defects.  BDO Kendalls does not accept liability for any loss or damage however caused which may 
result from this communication or any files attached.  A full version of the BDO Kendalls disclaimer, and our Privacy 
statement, can be found on the BDO Kendalls website at http://www.bdo.com.au or by emailing administrator () bdo com au 

BDO Kendalls is a national association of separate partnerships and entities.


From: listbounce () securityfocus com [listbounce () securityfocus com] On Behalf Of Tom Corelis [tomc () targetbilling 
Sent: Saturday, 29 December 2007 5:20 AM
To: Kappa Alpha Pi Eta
Cc: security-basics () securityfocus com
Subject: RE: Port-Knocking vulnerabilities?

I suppose you could do two successive port scans and hope the second
completes before the port-knockers' threshold.....

Tom Corelis

-----Original Message-----
From: listbounce () securityfocus com [mailto:listbounce () securityfocus com]
On Behalf Of Kappa Alpha Pi Eta
Sent: Friday, December 28, 2007 7:12 AM
To: security-basics () securityfocus com
Subject: Port-Knocking vulnerabilities?

Hi listers.

so I read this thread about port-knocking (altough called "reflexsive
firewalls"). I'd never heard of that and found that to be an very
interesting mechanism. Now I just keep wondering, what an attacker could
possibly do to intrude system secured in such a way. So there are no
open ports at all, also, there's no way the attacker could access the
computer physically or via social engineering. The attacker knows that a
knock-server is running and that there's some daemon waiting to become
accessible (what ever that may be).
What could a attacker do to somehow get access to that machine? And how
can I secure that machine from that kind of attacks.

Thanks in advance,
Express yourself instantly with MSN Messenger! Download today it's FREE!

  By Date           By Thread  

Current thread:
[ Nmap | Sec Tools | Mailing Lists | Site News | About/Contact | Advertising | Privacy ]