Great work and thanks for making it OSS! I was familiar with the prior (academic) work and its limitations, specifically TCP/IP. Could you elaborate on how you solved that problem?
(1) internal networking
If you run a test like `rust/network_hello_world.rs` under Hermit, then the communication between threads is part of the "deterministic bubble" that we're running inside of. When one thread blocks on a network call, the Hermit scheduler takes the thread out of the run pool, and it has to deterministically decide when it is ready to rejoin the run-pool by waking up. The scheduler proceeds in linear turns (labeled "COMMIT" in the logs), and if thread 5 unblocks from a network read at turn 100 in one run, it must unblock at that same point in time in all other runs.
Sometimes we use a precise model of the blocking operation (like with futexes) and other times we depend on sending Linux a non-blocking version of the syscall as a way to poll the IO and see if it is ready to complete (given the history of every operation that has committed on turns 1..N-1).
(2) external networking
This is impossible to determinize, of course. Unless you suck the whole network including both hosts into the deterministic bubble, as the DDOS fork of Linux experimented with in ~2013. That was kind of a negative result IMO because performance was pretty bad, but the paper is here:
https://www.dcc.fc.up.pt/~ines/aulas/1314/SDM/papers/DDOS.pdf