RE: Intrusion prevention and dDos protection

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• Maybe in reply to: Darren Windham: "Intrusion prevention and dDos protection"
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To: "'Rob Shein'" <shoten@starpower.net>, "'Darren Windham'" <dwindham@dallastelco.org>, <focus-ids@securityfocus.com>
Date: Tue, 26 Aug 2003 17:19:13 +0100

Rob,

You have a point. There are some considerations that may be pertinent with
regard to this issue. Firstly as you point out, there are no definitive
solutions. If there were any definitive solutions they would almost
certainly rely on good design practices and this is what is being advocated
here. Any connection to the Internet should include liaison and design with
the ISP. Most ISP's will allow rate limiting at the edge within their
domain if you request it. Similarly if you rate limit at your edge, you
control the traffic passing across the edge into your realm.

In terms of dropping traffic on the edge, again a DDOS can overwhelm the
resources dealing with incoming and outgoing traffic, however you can
control the switching of network traffic and the amount of CPU interrupts
called on most routers. By being granular in your approach and by black
holing non essential service specific traffic, you are less likely to
overwhelm your own critical network resources such as firewalls and routers.
This is done by specifying ports, disallowing fragmented traffic and non
essential traffic like ICMP.

Sadly my flawed assumptions require an in depth security solution that
involves many different parties. It is not ideal and only offers a limited
defence against a DDOS. The point being that this solution may be better
than nothing and if it can prevent you being hit by at least one DDOS, it
may be worth considering.

Regards

Paul Benedek
Director
Excis Networks Limited
http://www.excis.co.uk

-----Original Message-----
From: Rob Shein [mailto:shoten@starpower.net]
Sent: 26 August 2003 14:31
To: 'Paul Benedek'; 'Darren Windham'; focus-ids@securityfocus.com
Subject: RE: Intrusion prevention and dDos protection

Even this is predicated upon a critical and flawed assumption, being that
the pipe leading to your border router has more bandwidth than the pipe
leading from it. This is not the case; any rate limiting cannot be done by
you and must be done by the ISP itself. While this is possible, it is out
of the realm of product-based solutions and goes more towards cooperative
efforts with the ISP, which is the basis of all DDOS defense anyways.

Denying types of traffic at your border will be useless; that's like the
highly aware security guard at the front desk. The bad people aren't
getting past him, but it's already too late for that to matter.

> -----Original Message-----
> From: Paul Benedek [mailto:paul.benedek@excis.co.uk]
> Sent: Tuesday, August 26, 2003 5:18 AM
> To: 'Rob Shein'; 'Darren Windham'; focus-ids@securityfocus.com
> Subject: RE: Intrusion prevention and dDos protection
>
>
> Hi,
>
> Although the analogy is correct and that a well planned DDos
> attack can cause you to loose services, there are several
> things that you can do to limit the chances of success.
>
> Firstly at your ISP edge you can introduce rate limiting. By
> limiting the amount of certain types of traffic, you can
> allow for legitimate traffic to pass. For example if you
> have a 2 meg pipe, you can limit the amount of UDP to half a
> meg, tcp on port 80 and 443 to 1 meg and half a meg for other
> traffic. If the traffic exceeds these values, you can force
> the traffic to be dropped.
>
> If you are explicit with the traffic you are allowing, you
> can further limit the effects of a DDOS attack. For example
> you can deny all fragmented traffic and ICMP. You can
> specify the hosts and ports that need connectivity with a
> high degree of granularity and drop all other traffic.
> Furthermore if you implement RFC2827 filtering you can limit
> the chances of being used as a DDOS engine yourself.
>
> In most cases a well thought out DMZ and ISP edge can reduce
> the chances of a success, however as pointed out, you will
> not get total protection. You may however be able to keep
> critical services operational at the time of a DDOS attack.
>
>
> Regards,
>
> Paul Benedek
> Director
> Excis Networks Limited
> http://www.excis.co.uk
>
>
>
>
> -----Original Message-----
> From: Rob Shein [mailto:shoten@starpower.net]
> Sent: 23 August 2003 18:26
> To: 'Darren Windham'; focus-ids@securityfocus.com
> Subject: RE: Intrusion prevention and dDos protection
>
> I would hasten to point out that there isn't anything you can
> buy that will give you DDos protection. While a firewall/IPS
> is like a security guard at the entrance to a building to
> keep bad people out, a DDos attack is like so many bad people
> trying to get into the building that they choke the streets
> leading up to it; nothing you can put in your building will
> deal with that congestion or prevent it.
>
> > -----Original Message-----
> > From: Darren Windham [mailto:dwindham@dallastelco.org]
> > Sent: Thursday, August 21, 2003 10:17 AM
> > To: focus-ids@securityfocus.com
> > Subject: Intrusion prevention and dDos protection
> >
> >
> > I recently had the chance to meet with the guys over at
> > Melior and talk about their iSecure platform. Has anyone
> > else taken a look at it? I was pleasantly suprised at its
> > performance. I ran most of the common scanners on both Linux
> > and Windows platforms and had no such luck with it. I can
> > only hope that more products like this make it to the
> > mainstream marketplace. If you are looking for a IPS/dDos
> > prevention I'd make sure you take a good look at these guys.
> >
> > I'd love to hear feedback from others who have looked at this
> > or other similar products.
> >
> > Check them out at http://www.meliorinc.com
> >
> > Regards,
> >
> > Darren Windham
> > Network Administrator, Dallas Telco FCU
> > email: dwindham@dallastelco.org <mailto:dwindham@dallastelco.org>
> >
> >
> >
> >
> > Disclaimer: The information contained in this email is
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> >
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> technical IT security event. Modeled after the famous Black
> Hat event in
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---------------------------------------------------------------------------
Attend Black Hat Briefings & Training Federal, September 29-30 (Training), October 1-2 (Briefings) in Tysons Corner, VA; the world’s premier
technical IT security event. Modeled after the famous Black Hat event in
Las Vegas! 6 tracks, 12 training sessions, top speakers and sponsors.
Symanetc is the Diamond sponsor. Early-bird registration ends September 6 Visit: www.blackhat.com
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• Previous message: Andreas Krennmair: "Re: Network IDS"
• Maybe in reply to: Darren Windham: "Intrusion prevention and dDos protection"
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