Re: packet sniffers

[Gregory Nowak <greg@romuald.net.eu.org>]

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On Tue, Jun 27, 2006 at 01:43:15AM -0400, Jude DaShiell wrote:
> When you do something 
> like ifconfig eth0 -promisc up you're telling your ethernet card to only 
> listen for frames broadcast specifically to it and not to listen for any 
> other frames being broadcast to the left or right of your computer's 
> network connection. 

Quite the opposite is true actually. Putting the nic in promisc mode
tells it to listen for all packets on the network. Not putting the nic
into promisc mode tells it to just listen for packets meant for that
nic's IP address specifically.

> Unfortunately, the Linux default is to come up in 
> promiscuous mode when going onto the internet especially so with Debian. 

Wrong again. The gnu/linux default is to *not* bring up the interfaces
in promisc mode on startup. I've installed slackware, and debian on a
number of systems a number of times, and even installed gentoo
once. At no time did these installs result in bringing up the nics in
promisc mode at startup.

If what you're saying is actually what you've read, then I'd like to
have a look at the documents in question, so that I can either correct
my misinformation, or fire off an email to the authors responsible for
spreading such misinformation. Otherwise, I must conclude that you're
misinterpreting what you've read, in which case, it's no surprise to
me at all that you're dealing with packet sniffers and successful
cracking attempts on your system(s).

Greg




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