Lecture 16: Denial of Service

Intro to DoS

Application-Level DoS

Network-Level DoS

How might modern websites defend against DDoS attacks?


In the DNS amplification attack, what packets are sent across the network? For each packet, what are the source and destination fields set to?

TCP SYN Flooding

When using SYN cookies, after a legitimate client sends the ACK packet, how does the server know: 1) the client sequence number x, 2) the server sequence number y, and 3) any extra state that would have been stored after a SYN?

Application-Layer DoS

Algorithmic Complexity Attacks

How are algorithmic complexity attacks related to amplification attacks?

DoS Conclusion