pete > courses > Crash Course in System Security (CSCI 1005), Winter 2025 > Day 16
Day 16: NAT, VPN, and Tor
New(ish) tools
- tcpdump
- gnuplot
Exercises
Course Response Forms & CERP Survey
Organize Grading Meetings
I’ve set aside 9:00am to 12:00pm (noon) tomorrow (Friday) for grading meetings. Figure out among yourselves who will meet with me at what time. 10 minutes per student.
NAT in action
Recall that the MiddleburyCollege wireless network uses NAT. Identify the public IP address you’re using. Correlate with others in class to figure out the range of public IP addresses used for this purpose.
Set up a personal VPN
If you want to tinker with this, I suggest Wireguard. A more traditional choice is OpenVPN. Each is available as an Arch packages, and lots of documentation and examples configurations can be found online. I think there’s minimal short-term benefit to setting one up, which is why this one is labelled "optional", but if you want to play, go ahead.
Set up Tor
Self explanatory.
Traffic Analysis
(This is going to be easier using tcpdump, the command-line predecessor of Wireshark.)
Select a small (<20) collection of websites and characterize the packets (sizes and intervals) that flow back and forth when requesting each. Create one graph (see gnuplot) for each site. Have someone else pick one of the sites at random, visit it, and capture the packet trace. See if you can use your graphs to identify which site they visited. (This may require multiple experiments to produce sufficiently differentiable graphs, but since you wrote shell scripts to do all this, that should be easy, right?)