Security Basics mailing list archives
RE: Caching a sniffer
From: "Shawn Jackson" <sjackson () horizonusa com>
Date: Thu, 25 Mar 2004 12:50:38 -0800
Not really. I'm a switch, and I've just seen a new source MAC address, which I want to insert into my table. Uh-oh, the table is full. Instead of just failing to learn the new address, I'll "age out" the oldest address in the table prematurely to make space for the new one. (If I track their ages so I can age them out normally, finding the oldest one shouldn't be any problem.) I didn't "detect the flood" or alter the normal aging time. I just discarded some old information instead of discarding the new information just received. (In essence, this means treating the MAC table like a FIFO cache.)
I looked through some old docs on Cisco switches. To my knowledge the switches will automatically adjust the learning rate of the CAM table in much the same fashion your describing, but it doesn't really mitigate the effects of a MAC Address flood. Cisco called this attack "Forwarding Table Exhaustion", or at least that is what was in my notes. 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 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)