[OLUG] Promiscuous eth0

[Jason Ferguson]

Okay, makes sense... Im trying to learn some of this OSI and TCP/IP stuff
lately, but didnt quite grasp exactly what promiscuous mode meant. I knew
that the OS read the MAC addy to determine if the packet was for them or
not.

Jason


-----Original Message-----
From: Phil Brutsche [mailto:pbrutsch at creighton.edu]
Sent: Saturday, April 15, 2000 9:48 PM
To: olug at bstc.net
Subject: RE: [OLUG] Promiscuous eth0


A long time ago, in a galaxy far, far way, someone said...

> Okay, I'm dumb... can someone explain promiscuous mode to me and why its a
> bad thing?

Normally, when a network card recieves a packet over the wire, it
determines if it should tell the OS about the packet if it's destined for
that network card, based on the destination hardware address - the MAC
address when dealing with ethernet.

In promiscuous mode, an ethernet card tells the operating system about a
packet it recieves over the wire, period.  This mode is typically used by
packet sniffers.  That's why Vincent said he'd be worried if he saw that
in his logs - if he's not running the packet sniffer, someone must be.
Since running a packet sniffer requires root access, that would mean that
your system was compromised (aka "hacked") in some way.

--
----------------------------------------------------------------------
Phil Brutsche					pbrutsch at creighton.edu

"There are two things that are infinite; Human stupidity and the
universe. And I'm not sure about the universe." - Albert Einstein


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