Security Basics mailing list archives
RE: Caching a sniffer
From: "Shawn Jackson" <sjackson () horizonusa com>
Date: Thu, 25 Mar 2004 08:36:31 -0800
A switch is not a hub/router. In fact it is a micro segmented bridge.
It's nice I get so much attention, you all sure know how to make a man feel wanted :-). Now let the rebuttal begin. As my response to Fernando, which hopefully will get posted to the list soon then this message, states that switches have numerous functionality and systems that operate at higher layers of the OSI model then just 2. As with most network connected devices they need to have functionality on other layers besides the one where their core functionality resides. Case in point, bridges merely forward traffic destined to address on other interfaces, limiting broadcast in each segment, this is the core functionality of a switch. I will retract my earlier statement in place of this one which better suites the core functionality of the switch, in this case you guys win. With that stated, switches can make decisions on traffic based on IP information which resides at the Network layer (layer 3) of the OSI model, as opposed to MAC address information which resides at the Data-Link layer (layer 2) of the OSI model. Most switches provide IGMP functionality for systems to announce they multicast group membership, which is all layer 3 data. Some switches allow you to set ACL's or security based on IP information, not just MAC or layer 2 information. Some switch can also make routing or 'gateway of last resort' decisions.
A switch operates at layer 2 of the OSI model i.e. MAC address layer.
Layer 2 of the OSI model is the Data Link layer. LLC and MAC are logical parts of that layer and not layers themselves.
Therefore if someone has plugged a scanner into a network point they
will not be
able to sniff any useful information from the network unless that
person has admin
access to the switch. You can check this by ensuring that none of the
ports on the
switches are in span mode
Through ARP poising, brought up by David, and MacOf which I mentioned allow people to sniff traffic on a switched network. You don't need to be using SPAN to sniff traffic, that just the way us admins do it. Shawn Jackson Systems Administrator Horizon USA 1190 Trademark Dr #107 Reno NV 89521 www.horizonusa.com Email: sjackson () horizonusa com Phone: (775) 858-2338 (800) 325-1199 x338 --------------------------------------------------------------------------- Ethical Hacking at the InfoSec Institute. Mention this ad and get $545 off any course! All of our class sizes are guaranteed to be 10 students or less to facilitate one-on-one interaction with one of our expert instructors. Attend a course taught by an expert instructor with years of in-the-field pen testing experience in our state of the art hacking lab. Master the skills of an Ethical Hacker to better assess the security of your organization. Visit us at: http://www.infosecinstitute.com/courses/ethical_hacking_training.html ----------------------------------------------------------------------------
Current thread:
- RE: Caching a sniffer, (continued)
- RE: Caching a sniffer Paul Blackstone (Mar 25)
- RE: Caching a sniffer Byron Copeland (Mar 26)
- Re: Caching a sniffer Aaron (Mar 29)
- RE: Caching a sniffer Paul Blackstone (Mar 25)
- RE: Caching a sniffer David Gillett (Mar 25)
- RE: Caching a sniffer Andrew Shore (Mar 25)
- RE: Caching a sniffer Shawn Jackson (Mar 25)
- RE: Caching a sniffer Shawn Jackson (Mar 25)
- RE: Caching a sniffer David Gillett (Mar 26)
- RE: Caching a sniffer Shawn Jackson (Mar 25)
- RE: Caching a sniffer David Gillett (Mar 25)
- RE: Caching a sniffer Shawn Jackson (Mar 25)
- RE: Caching a sniffer Andrew Shore (Mar 25)
- RE: Caching a sniffer Shawn Jackson (Mar 25)
- RE: Caching a sniffer David Gillett (Mar 26)
- RE: Caching a sniffer Shawn Jackson (Mar 26)
- RE: Caching a sniffer Shawn Jackson (Mar 26)
- RE: Caching a sniffer Nero, Nick (Mar 26)
- Re: Caching a sniffer aruna (Mar 29)
- Re: Caching a sniffer Mitchell Rowton (Mar 30)