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  1. 1. ./whoami 0 If You want to Hack some one First Hack Your self. 0 I am NOT a Hacker Just Learning for Security analyst.
  2. 2. Why DoS? 0 Sub-cultural status 0 To gain access 0 Revenge 0 Political reasons 0 Economic reasons 0 Nastiness
  3. 3. How DoS (remotely)? 0 Consume host resources 0 Memory 0 Processor cycles 0 Network state 0 Consume network resources 0 Bandwidth 0 Router resources (it’s a host too!) 0 Exploit protocol vulnerabilities 0 Poison ARP cache 0 Poison DNS cache 0 Etc…
  4. 4. Where DoS 0 End hosts 0 Critical servers (disrupt C/S network) 0 Web, File, Authentication, Update 0 DNS 0 Infrastructure 0 Routers within org 0 All routers in upstream path
  5. 5. Outline  What is a DDOS attack?  How to defend a DDoS attack?
  6. 6. What is DDoS attack? • Internet DDoS attack is real threat 0 0 0 - on websites · Yahoo, CNN, Amazon, eBay, etc (Feb. 2000) services were unavailable for several hours on Internet infrastructure 13 root DNS servers (Oct, 2002) 7 of them were shut down, 2 others partially unavailable • Lack of defense mechanism on current Internet
  7. 7. What is a DDos Attack? 0 Examples of DoS include: 0 Flooding a network 0 Disrupting connections between machines 0 Disrupting a service 0 Distributed Denial-of-Service Attacks 0 Many machines are involved in the attack against one or more victim(s)
  10. 10. What Makes DDoS Attacks Possible? 0 Internet was designed with functionality & not security in mind 0 Internet security is highly interdependent 0 Internet resources are limited 0 Power of many is greater than power of a few
  11. 11. IP Traceback - Allows victim to identify the origin of attackers - Several approaches ICMP trace messages, Probabilistic Packet Marking, Hash-based IP Traceback, etc.
  12. 12. PPM 0 Probabilistic Packet Marking scheme - Probabilistically inscribe local path info - Use constant space in the packet header - Reconstruct the attack path with high probability Marking at router R For each packet w Generate a random number x from [0,1) If x < p then Write IP address of R into w.head Write 0 into w.distance else if w.distance == 0 then write IP address of R into w.tail Increase w.distance endif
  13. 13. PPM (Cont.) legitimate user attacker Victim DDoS Attack and Its Defense 16
  14. 14. PPM (Cont.) legitimate user attacker Victim DDoS Attack and Its Defense 17
  15. 15. PPM (Cont.) legitimate user attacker R R R R R Victim V DDoS Attack and Its Defense 18
  16. 16. What is Pushback? 0 A mechanism that allows a router to request adjacent upstream routers to limit the rate of traffic
  17. 17. How Does it Work? 0 A congested router requests adjacent routers to limit the rate of traffic for that particular aggregate 0 Router sends pushback message 0 Received routers propagate pushback
  18. 18. How Does it Work?
  19. 19. When is it invoked? 0 Drop rate for an aggregate exceeds the limit imposed on it (monitoring the queue) 0 Pushback agent receives information that a DoS attack is underway (packet drop history)
  20. 20. When does it stop? 0 Feedback messages are sent to upstream routers that report on how much traffic from the aggregates is still present
  21. 21. What are some advantages? 0 Pushback prevents bandwidth from being wasted on packets that will later be dropped (better when closer to the source) 0 Protects other traffic from the attack traffic 0 When network is under attack it can rate limit the malicious traffic
  22. 22. Conclusion 0 Defending a DDoS attack 0 Ingress filtering 0 Traceback 0 Pushback
  23. 23. !! For Regarding any question contact me !! http://www.maulikkotak.webnode.com http://www.facebook.com/maulikkotakstar http://www.twitter.com/maulikkotakstar
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