Module 11 Overview
March 29 - April 4 · Reading: 17 pages · Due: D4 · Estimated total: 6 hours
The internet's core protocols were designed by people who were solving a different problem. They were building something that would keep working when links failed and routers died, among institutions that broadly trusted each other. Almost none of it authenticates anything.
That inheritance explains most of this week:
- ARP (Address Resolution Protocol) (Address Resolution Protocol), which finds the hardware address that goes with an IP (Internet Protocol) address on a local network, believes any reply.
- DNS (Domain Name System) (Domain Name System), which turns names like
boisestate.eduinto addresses, believed any answer until DNSSEC (Domain Name System Security Extensions) (DNS Security Extensions) added signatures. - BGP (Border Gateway Protocol) (Border Gateway Protocol), which networks use to tell each other how to reach addresses, largely believes any route announcement.
- TCP (Transmission Control Protocol) (Transmission Control Protocol) uses sequence numbers to keep data in order, which gives robustness against faults, not against an adversary.
Every one of those is a design that was correct for its requirements and became a vulnerability when the requirements changed.
The second half of the week is what defenders do about it: firewalling, segmentation, monitoring, and the observation that in a world where nearly all traffic is encrypted, a network sensor sees metadata rather than content, and metadata turns out to be enough for a great deal.
Learning Objectives
By the end of this week, the successful student will be able to:
- 4.1: Explain how common network attacks work at the protocol layer where they operate.
- 4.2: Recommend network defenses (firewalling, segmentation, and monitoring) for a described network.
Assignments and Tasks
Due by Thursday at 11:59 p.m. Mountain Time
- Read 11.01 Readings and Lecture Notes and work through the worked example (2 hrs 40 min)
- Write your initial post in 11.02 D4: Network Security in the News
- D4 asks you to find an incident nobody else has claimed. Check the board and post early.
Due by Sunday at 11:59 p.m. Mountain Time
- Write two replies in 11.03 D4: Network Security in the News - Replies (1 hr with the initial post, 30 points)
Time Estimate
| Activity | Time |
|---|---|
| Reading (17 pages) | 2 hrs |
| The notes page and the worked example | 40 min |
| D4 post and two replies | 1 hr |
| Review and slack | 2 hrs 30 min |
| Total | ~6 hrs |