Re: Asymmetric traffic/topology

[Jeremy Bennett <jeremy () deities org>]

I cannot site specific marketing or survey data. What I shared was  
based on my own experience developing networking and security  
products including working on a commercial IPS product for over 5 years.

-J
On Nov 8, 2007, at 8:37 PM, snort user wrote:

> Jeremy,
>
> Do you have any reference for the information that you provided?
>
> Thanks
>
> On Nov 8, 2007 6:06 PM, Jeremy Bennett <jeremy () deities org> wrote:
> > First there are three types of asymmetry in a network that can cause
> > problems for some times of IPS devices.
> >
> > 1. Connection-level asymmetry: This is the case where a given TCP
> > connection (up and down stream) is on a single network path but a
> > separate, identical connection may follow a different path. This is
> > very common and can cause problems for behavioral systems.
> >
> > 2. Flow-level asymmetry: This is the case where the upstream and
> > downstream flows in a TCP connection may follow different paths. This
> > can cause problems for behavioral systems and stateful packet-
> > inspection.
> >
> > 3. Packet-level asymmetry: This is the case packets within a flow may
> > be following different routes in a network. This can cause problems
> > for any IPS except for the most basic packet-filter.
> >
> > Now in my experience, #1 is very common in medium to large
> > enterprises that have built for scalability and redundancy. #2 is
> > common in load-balanced server farms. #3 is not extremely common but
> > does appear in some instances of a hot-hot redundancy deployment.
> >
> >
> > -J
> >
> >
> > On Nov 7, 2007, at 4:42 PM, snort user wrote:
> >
> > > Greetings.
> > >
> > > I am sure that most of you know about the asymmetric traffic/ 
> > > topology
> > > problem in relevance to
> > > IDS/IPS systems.
> > > ( By Asymmetric traffic/topology, I mean the case where client to
> > > server packets traverse a different path
> > > in your network compared to server to client packets. Hence the
> > > IDS/IPS see only one side of the conversation)
> > >
> > > I am trying to find out how wide this problem really is?
> > > Is it commonly seen in large / enterprise networks ?
> > >
> > > Any input is welcome.
> > >
> > > Thanks
> > >
> > > -------------------------------------------------------------------- 
> > > --
> > > --
> > > Test Your IDS
> > >
> > > Is your IDS deployed correctly?
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> >
> > > module=Form&action=impact&campaign=intro_sfw
> > > to learn more.
> > > -------------------------------------------------------------------- 
> > > --
> > > --
>
> ---------------------------------------------------------------------- 
> --
> Test Your IDS
>
> Is your IDS deployed correctly?
> Find out quickly and easily by testing it
> with real-world attacks from CORE IMPACT.
> Go to http://www.coresecurity.com/index.php5? 
> module=Form&action=impact&campaign=intro_sfw
> to learn more.
> ---------------------------------------------------------------------- 
> --


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Test Your IDS

Is your IDS deployed correctly?
Find out quickly and easily by testing it 
with real-world attacks from CORE IMPACT.
Go to http://www.coresecurity.com/index.php5?module=Form&action=impact&campaign=intro_sfw 
to learn more.
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