Security Basics mailing list archives
RE: Caching a sniffer
From: "David Gillett" <gillettdavid () fhda edu>
Date: Wed, 24 Mar 2004 12:15:52 -0800
-----Original Message----- From: Shawn Jackson [mailto:sjackson () horizonusa com]1. Dump the entire MAC table. Switch acts as if power on reset just occurred.Seams logical, but I've never seen it implemented. It would halt traffic while learning resumes, in addition if other checks needed to run (Spanning Tree/CDP) it would take much longer.
No. Traffic will flood while learning restarts from scratch. Nothing was said about dumping STP/CDP statuses.
2. Stop learning. All previously learned MAC addresses remain, and so only traffic for unrecognized MAC addresses gets sent to all ports.That would damage the network. If a new client fires up, they would not get added to the switches tables and not receive any traffic.
Destinations not in the table normally get flooded, not dropped. Dropping this traffic is possible, but not a normal part of the action being suggested.
3. Partial Purge of table. Some portion of the table gets purged and the switch continues, treating those purged MAC addresses as if this was the first time they were seen. Depending upon how the purged addresses are selected - oldest first, youngest first, random, lowest MAC addresses, highest MAC addresses or something else - will cause the switch to act differently for different users.Seams a better solution out of the bunch, could be a pain to implement.
Some switches routinely age unused entries out of the table. Accelerating this process if the table fills shouldn't be too hard.
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Current thread:
- RE: Caching a sniffer, (continued)
- RE: Caching a sniffer Burton M. Strauss III (Mar 25)
- RE: Caching a sniffer Fernando Gont (Mar 25)
- RE: Caching a sniffer Shawn Jackson (Mar 24)
- RE: Caching a sniffer David Gillett (Mar 24)
- RE: Caching a sniffer Fernando Gont (Mar 25)
- RE: Caching a sniffer David Gillett (Mar 25)
- RE: Caching a sniffer David Gillett (Mar 24)
- RE: Caching a sniffer Fernando Gont (Mar 25)
- 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 David Gillett (Mar 25)
- RE: Caching a sniffer Shawn Jackson (Mar 25)
- RE: Caching a sniffer Andrew Shore (Mar 25)
- 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 David Gillett (Mar 26)