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Firezone uses ICMP errors to signal to client applications that e.g. a certain IP is not reachable. This happens for example if a DNS resource only resolves to IPv4 addresses yet the client application attempted to use an IPv6 proxy address to connect to it. In the presence of traffic filters for such a resource that does _not_ allow ICMP, we currently filter out these ICMP errors because - well - ICMP traffic is not allowed! However, even in the presence of ICMP traffic being allowed, we would fail to evaluate this filter because the ICMP error packet is not an ICMP echo reply and therefore doesn't have an ICMP identifier. We require this in the DNS resource NAT to identify "connections" and NAT them correctly. The same L4 component is used to evaluate the traffic filters. ICMP errors are critical to many usage scenarios and algorithms like happy-eyeballs. Dropping them usually results in weird behaviour as client applications can then only react to timeouts.
Rust development guide
Firezone uses Rust for all data plane components. This directory contains the Linux and Windows clients, and low-level networking implementations related to STUN/TURN.
We target the last stable release of Rust using rust-toolchain.toml.
If you are using rustup, that is automatically handled for you.
Otherwise, ensure you have the latest stable version of Rust installed.
Reading Client logs
The Client logs are written as JSONL for machine-readability.
To make them more human-friendly, pipe them through jq like this:
cd path/to/logs # e.g. `$HOME/.cache/dev.firezone.client/data/logs` on Linux
cat *.log | jq -r '"\(.time) \(.severity) \(.message)"'
Resulting in, e.g.
2024-04-01T18:25:47.237661392Z INFO started log
2024-04-01T18:25:47.238193266Z INFO GIT_VERSION = 1.0.0-pre.11-35-gcc0d43531
2024-04-01T18:25:48.295243016Z INFO No token / actor_name on disk, starting in signed-out state
2024-04-01T18:25:48.295360641Z INFO null
Benchmarking on Linux
The recommended way for benchmarking any of the Rust components is Linux' perf utility.
For example, to attach to a running application, do:
- Ensure the binary you are profiling is compiled with the
releaseprofile. sudo perf record -g --freq 10000 --pid $(pgrep <your-binary>).- Run the speed test or whatever load-inducing task you want to measure.
sudo perf script > profile.perf- Open profiler.firefox.com and load
profile.perf
Instead of attaching to a process with --pid, you can also specify the path to executable directly.
That is useful if you want to capture perf data for a test or a micro-benchmark.