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Re: [ISSForum] Inline Appliance and Switch Configuration

Subject: Re: [ISSForum] Inline Appliance and Switch Configuration
Date: Tue, 12 Jul 2005 22:39:34 +0200
Hi,

I just want to re explain the way the Proventia G works, and how you 
should plug the box in production.

First, you need to know that the box is pluged on the network OFF. Don't 
plug the power on your box, just plug the network and the network 
traffic should go.

The only think you need to know is that the bypass unit (included for 
copper interface) works as a cross over unit when the appliance is power 
off.

So if you want to plug the appliance in place of a straight cable, you 
have to use a straight cable and a cross over cable (included, green 
short cable).

Then, you power on the appliance. By default each interface are in Auto 
Mode. This auto mode concern the classic speed and mode negociation, but 
it include also if the interface is crossed or not.
To avoid this negociation (taking some time and not always efficiant) 
you should force the speed and mode of the interface. But in this case 
the interface works as a classic 'PC' interface (not crossed). So you 
should use more cross over cable.

Take a look at these training excercices:
Ex 1]
Configuration:
[Firewall]<--Straight Cable-->[Switch]

Please place straight or cross over cable and the appliance.
Answer:
[Firewall]<--SC-->[Proventia G]<--COC-->[Switch]
Power off: the traffic pass through, because the appliance is a 
crossover unit.
Power on: the traffic pass through, in AUTO mode only.
For forced mode you should use this configuration:
[Firewall]<--COC-->[Proventia G]<--SC-->[Switch]
So the place where you put the cross over cable is important.

Ex2]
Configuration:
[Router]<--CrossOver Cable-->[Firewall]
Answer:
[Router]<--SC-->[Proventia G]<--SC-->[Firewall]
Power off: the traffic pass through.
Power on: the traffic pass through, in AUTO mode only.
For forced mode you should use this configuration:
[Router]<--COC-->[Proventia G]<--COC-->[Firewall]


Hope this helps.

-ben.


McLean, Michael R wrote:
David:
 
That would be wonderful if you had anything to help the pain.
 
Thanks,
MRM

-----Original Message-----
From: CAUSEY, David [mailto:davidc@lmi.org]
Sent: Friday, July 08, 2005 9:12 PM
To: McLean, Michael R; Matt Kaar; Chris Norris/AMIG
Cc: ISSForum@iss.net
Subject: RE: [ISSForum] Inline Appliance and Switch Configuration



Yes, I have been here too. When we set things up about 1 1/2 years ago I had 
the exact same questions and issues. We have a Pro G. and wanted it to sit 
between a Cisco PIX firewall and Cisco 65xx series switch. It worked fine 
when things were on but if it was powered down there were lots of problems 
getting the PIX and the Cisco 6500 to renegotiate. 

 

I called ISS and they pretty much read the book to me which was no help. I 
already knew what the book said... "the Pro g fails open, it does nothing to 
change the data flow, it just passes from NIC A to B, etc". But that isn't 
really true. It does do something. When it would either power off, have the 
services stopped or go through a warm boot we had differing results. So it 
must be doing something! It isn't truly a passive pass-through as ISS claims. 
If that were true then off or on the Cisco devices on both sides would not 
have a need to renegotiate. 

 

I opened a call with Cisco also and they concur with what people are saying 
in this forum. PortFast needs to be ON. I tried every combo and ran tons of 
simulations to see. The fastest I was able to obtain was about a 15-30 second 
outage while ports renegotiated during a Proventia power outage. When the Pro 
G came back up there was no delay at all. I think ISS says you lose 1 packet. 
With portfast off the reneg. time was more like several minutes I believe. 
(this was 1.5 years ago) I do remember you had to have a crossover cable on 
one side of the Pro G. (it did not matter which side).

 

I will try to find the docs I created at the time and post those results. 
(btw... because of some other issues we put a smaller switch (Cisco 2924) on 
both sides of the Pro G and that solved a lot of those slow reneg. times. So 
our config now goes:

 

 Internet <> Cisco 2924 (outside firewall) <> Pro G port B / Pro G port A <> 
Cisco 2924 (inside firewall) <> Cisco 65xx <> internal network

 

I'll look for those notes which I created BEFORE adding the 2924's.

 

 

David

 

 

 

-----Original Message-----
From: issforum-bounces@iss.net [mailto:issforum-bounces@iss.net] On Behalf Of 
McLean, Michael R
Sent: Tuesday, June 28, 2005 11:59 AM
To: Matt Kaar; Chris Norris/AMIG
Cc: ISSForum@iss.net
Subject: Re: [ISSForum] Inline Appliance and Switch Configuration

 

We will be doing the same thing, so I am very interested in your experience.

And I will provide our experience to all.

 

MRM

 

-----Original Message-----

From: Matt Kaar [mailto:matt.kaar@gmail.com]

Sent: Tuesday, June 28, 2005 8:54 AM

To: Chris Norris/AMIG

Cc: ISSForum@iss.net

Subject: Re: [ISSForum] Inline Appliance and Switch Configuration

 

 

Chris,

 

I wrestled with this question about a year ago while working with G 

appliances and here's my take on it. Though I have not played with 

uplinkfast or backbonefast, I recommended enabling portfast on those ports 

connected to the G. Here's my reasoning (and it's been a while since I've 

done this, so anyone feel free to correct me :)

 

Spannning tree's main purpose is to avoid switching loops within your 

network. Now, if you take a fully functioning network with IPS working and 

you don't have switching loops, then you just need to worry about when 

link-state goes down on the G for that split second. If there are no loops 

created during that period of time, you can bring the G back up w/o waiting 

through the STP learning period and have no problems. Since the period of 

time that the link-state is actually down is fairly small (less than a 

second IIRC), you're betting that no one will create a switching loop on 

another part of your network during that time.

 

Since connectivity after a G power loss was a paramount concern, I 

recommended using portfast to bring those switch ports up as fast as 

possible. Your environment may have different requirements, so as usual 

YMMV.

 

-Matt

--

Matt Kaar, CISSP

Carnegie Mellon University

Information Networking Institute

matt.kaar@gmail.com 

 

On 6/24/05, Chris Norris/AMIG <CNorris@amig.com> wrote:



Just curious to know how others are handling the physical install of 


Inline


IDP devices. We are looking to move our Proventia G to inline mode as it


wasn't installed this way originally.



I was told that in "acts just like a cable" and would not be a problem in


passing traffic in the event of a power failure on the device. That's not


exactly true. With no power it passes traffic "like a cable" but when 


power


is present the IDP establishes link-state with the 2 switches it's


connected to. When power is lost so is link-state with the switches which


can invoke a spanning-tree change.



This is what happened during our test. It's too bad that the device is not


truly "passive" from a link-state perspective so that it would allow the


switches to "see" each other through the IDP, but it is what it is.



So my suggestion to our network team is to look at options such as


"uplinkfast" or "backbonefast" since they are using Cisco switches. I


suppose they could use "portfast" on the IDP ports but I have always


frowned on "portfast" (which disables Spanning-Tree learning mode) on


anything but end user ports.



What are other people doing?



Regards,


Chris Norris CISSP


American Modern Insurance Companies


Sr. Security Engineer


IS Risk and Security Management



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6303 Barfield Road, Atlanta, Georgia, USA 30328.

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The ISSForum mailing list is hosted and managed by Internet Security Systems, 
6303 Barfield Road, Atlanta, Georgia, USA 30328.



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