What Reaction to Packet Loss Reveals About VPN

Explore the intricacies of VPN behavior and packet loss in this informative conference talk from BSidesLV 2014. Delve into the technical aspects of OpenVPN, IPSec, and network protocols as speakers Sergey Bratus and Anna Shubina present their findings on how VPNs react to packet loss. Learn about packet timings, kernel behaviors, and the impact of algorithms like Nagle's and delayed ACK. Discover surprising insights from experiments with UDP packet dropping, IPSec fingerprints, and the effects of network queues. Gain a deeper understanding of VPN performance across various scenarios, including slow data transmission and chaining modes. Conclude with non-intuitive takeaways and potential areas for future research in this 36-minute presentation that challenges conventional wisdom about VPN operations.

Intro
OpenVPN, each 5th packet
Once upon a time...
Behind the scenes...
Packet timings: routers
PortBunny: kernels
Nagle's algorithm vs delayed ACK
Just your normal VPN...
Experiment
100-packet timings for OpenVPN UDP, each 5th packet dropped
IPSec fingerprints
Netcat is sneaky
What about chaining mode?
Slow data (across US)
It's all about queues
What is going on?
Profiling attempt
Non-intuitive take-away?
Future work