Discovery Discussion of Security.

[Alex.]

Found some info...

Black-holing or sinkholing: This approach blocks all traffic and diverts it to a black hole, where it is discarded. The downside is that all traffic is discarded -- both good and bad -- and the targeted business is taken off-line. Similarly, packet-filtering and rate-limiting measures simply shut everything down, denying access to legitimate users.

Routers and firewalls: Routers can be configured to stop simple ping attacks by filtering nonessential protocols and can also stop invalid IP addresses. However, routers are typically ineffective against a more sophisticated spoofed attack and application-level attacks using valid IP addresses. Firewalls can shut down a specific flow associated with an attack, but like routers, they can't perform antispoofing.

Intrusion-detection systems: IDS solutions will provide some anomaly-detection capabilities so they will recognize when valid protocols are being used as an attack vehicle. They can be used in conjunction with firewalls to automatically block traffic. On the downside, they're not automated, so they need manual tuning by security experts, and they often generate false positives.

Servers: Proper configuration of server applications is critical in minimizing the effect of a DDoS attack. An administrator can explicitly define what resources an application can use and how it will respond to requests from clients. Combined with a DDoS mitigation appliance, optimized servers stand a chance of continued operations through a DDoS attack.

DDoS mitigation appliances: Several companies either make devices dedicated to sanitizing traffic or build DDoS mitigation functionality into devices used primarily for other functions such as load balancing or firewalling. These devices have varying levels of effectiveness. None is perfect. Some legitimate traffic will be dropped, and some illegitimate traffic will get to the server. The server infrastructure will have to be robust enough to handle this traffic and continue to serve legitimate clients.

Over-provisioning: or buying excess bandwidth or redundant network devices to handle spikes in demand can be an effective approach to handling DDoS attacks. One advantage of using an outsourced service provider is that you can buy services on demand, such as burstable circuits that give you more bandwidth when you need it, rather than making an expensive capital investment in redundant network interfaces and devices.
For the most part, companies don't know in advance that a DDoS attack is coming. The nature of an attack will often change midstream, requiring the company to react quickly and continuously over several hours or days. Since the primary effect of most attacks is to consume your Internet bandwidth, a well-equipped managed hosting provider has both the bandwidth and appliances to mitigate the effects of an attack.

Conclusion
DDoS attacks are destructive stealth weapons that can shutter a business. Our reliance on the Internet continues to grow, and the threat of DDoS attacks continues to expand. Organizations need to ensure operational continuity and resource availability with a vigilant DDoS mitigation approach if they want to conduct "business as usual."
Paul Froutan is vice president of engineering at Rackspace Managed Hosting, a provider of managed hosting services in San Antonio. An expert in traffic analysis and server scalability, he also holds a U.S. patent for his IDS, part of Rackspace's PrevenTier three-tier security system designed to help identify and mitigate the effects of DDoS attacks.