[Snort-users] snort and network tap

Scot Scot scotw at ...125...
Wed Oct 16 21:22:01 EDT 2002

Your TAP's are going to provide you with full-duplex traffic. If your
traffic is not to high, 40MB or more, you will probably get away with using
a hub. Regardless of the traffic load you will always stand a higher risk of
loosing traffic using a half-duplex repeating (hub) device. I would
recommend using a full-duplex switch to combine the traffic. You can then
setup a mirrored, SPANed, or roving port (depending on what the
manufacturer's lingo is for the switch you are using) to forward the
combined traffic to your snort sensor.

 TAP---Rx---- |     Switch            |----Mirrored Port------
TAP---Tx----  |                           |
If you have the $$$$$ laying around, many switches now do Layer 2-7
switching. This will allow you to forward specific types of Application
traffic. Just to throw one out off the top of my head:



Just my 2.0134 cents worth (tax included)

Scot Wiedenfeld

----- Original Message -----
From: "Peter Erickson" <redlamb at ...7185...>
To: "Snort-Users List" <snort-users at lists.sourceforge.net>
Sent: Wednesday, October 16, 2002 12:06 PM
Subject: [Snort-users] snort and network tap

> I am in the process of attaching snort to a network and am not too sure on
how to attach it with the network tap that I have. I have the Finisar UTP
IL/1. I have been told to connect the 2 tap ports on the Network Tap to a
hub and then connect the snort machine to the hub, but after reading some
articles on the Snort-Users archive, I heard that I wil lose too many
packets due to collisions and that this would not be a good choice. I also
read on the snort FAQ that I can not run 1 instance of snort to monitor 2
interfaces, so I guess that is not too good of an options either. I am just
wondering what the best way to connect my snort machine to the network using
the network tap that I have. Thanks in advance.
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