1. Prolog to Lecture 18 CS 236 On-Line MS Program Networks and Systems Security Peter Reiher

2. DDoS In the Real World Do DDoS attacks really happen?
What responses are taken in real cases?
What tools are available and used today to handle DDoS?

3. Real World Occurrence of DDoS
Estonia, Georgia, Iran, Australia governments have all suffered large DDoS attacks in recent years
Companies also get attacked fairly often
Usually for extortion
Sony recently attacked as part of larger attack
It’s pretty common

4. So What Do Victims Do? Generally, either last it out
Or pay extortion, if that’s the goal of the attacker
Or enlist help from ISP
Who may, in turn, enlist help of other parties

5. How Do ISPs Help? Two approaches: Drop traffic
Block attacking machines

6. Dropping Traffic Drop traffic before it gets to the victim
Which traffic?
Usually, ISP engineers examine data flows by hand
Dropping obvious attack flows
Or all traffic from obvious attack sources
May need to get upstream ISPs to help
Generally a blunt instrument
And not quick

7. Blocking the Bots Can’t just block them near the target
Must get them further upstream
Generally at their entry to the Internet
Requires cooperation of their providers
Won’t do it for just anyone
A lot of work, if there are lots of bots

8. Content Distribution Network Approaches
Akamai and similar companies can help their customers
They maintain cached copies of customer content
And have huge server pools spread around the Internet
How does that help?

9. The Resource Multiplication Solution
Cache content at vast number of places
As demand increases, increase caching
Few attackers can overwhelm big enough cache providers
Who could charge for the protection
A feasible solution, but not cheap

10. Do Practical Measures Work?
If you can get the necessary parties to help, usually yes
What’s theoretically hard might not be too bad, in practice
If you are important enough
Small fry are likely to get squashed