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Re: Monitoring Multiple Subnets
From: Shaun Marlin <shaun.marlin () canalta com>
Date: Mon, 13 May 2013 15:23:55 +0000

That does make sense.  The thing that I am most concerned about is because there is an unmanaged switch, could it fail? 
 I would love to have a SPAN setup, but that isn't in the budget.

From: Seth Dunn [mailto:seth () d2ms com]
Sent: Monday, May 13, 2013 9:17 AM
To: Shaun Marlin; snort-users () lists sourceforge net
Subject: RE: [Snort-users] Monitoring Multiple Subnets

For what I did....I don't have quite the same setup as you, but I needed to monitor multiple LANs.
10.75.x.x/24 and 10.76.x.x/24
I am using a Cisco switch for my networks.
I set up SPAN on my switch, RSPAN is also available, to copy traffic from two ports in which inbound/outbound traffic 
flows for these LANs.....and set up the destination port for the port that my Snort box is listening on.

Then as someone noted, in your snort.conf file you need to make sure these two networks are part of your $HOME variable.

From: Shaun Marlin [mailto:shaun.marlin () canalta com]
Sent: Monday, May 13, 2013 11:04 AM
To: snort-users () lists sourceforge net<mailto:snort-users () lists sourceforge net>
Subject: [Snort-users] Monitoring Multiple Subnets

I am building a SNORT box to monitor my network.  I have 2 ISP's.  Is it possible to have the 2 ISP's connect into an 
unmanaged switch, then have SNORT configured with an IP from each block that I have, and finally pass the traffic back 
onto the switch that goes into my network?

Sorry for the run on question there

Essentially I am looking for something like this


[cid:image001.png@01CE4FBB.9755E2F0]ISP 1
                                               Router 1                                                                 
                                                                                                      Internal Network



[cid:image011.png@01CE4FBB.9755E2F0]ISP 2                                                                               
                                                              Router 2


                                Unmanaged Switch

SNORT would endup monitoring 3 different subnets.  For instance and

Does anyone see a reason why this would not work

Shaun Marlin
Network Administrator

Canalta Family of Companies

2109 - 545 Highway 10 East
Drumheller AB Canada T0J 0Y0
PHONE: (403) 820-3865
CELL:     (403) 334-1313

EMAIL:   shaun.marlin () canalta com<mailto:shaun.marlin () canalta com>
WEB:      www.canalta.com<http://www.canalta.com>

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