Files
firezone/rust/headless-client
Thomas Eizinger 3e6094af8d feat(linux): try to set rmem_max and wmem_max on startup (#10349)
The default send and receive buffer sizes on Linux are too small (only
~200 KB). Checking `nstat` after an iperf run revealed that the number
of dropped packets in the first interval directly correlates with the
number of receive buffer errors reported by `nstat`.

We already try to increase the send and receive buffer sizes for our UDP
socket but unfortunately, we cannot increase them beyond what the system
limits them to. To workaround this, we try to set `rmem_max` and
`wmem_max` during startup of the Linux headless client and Gateway. This
behaviour can be disabled by setting `FIREZONE_NO_INC_BUF=true`.

This doesn't work in Docker unfortunately, so we set the values manually
in the CI perf tests and verify after the test that we didn't encounter
any send and receive buffer errors.

It is yet to be determined how we should deal with this problem for all
the GUI clients. See #10350 as an issue tracking that.

Unfortunately, this doesn't fix all packet drops during the first iperf
interval. With this PR, we now see packet drops on the interface itself.
2025-09-17 23:05:01 +00:00
..

headless-client

This crate acts as the CLI / headless Client, and the privileged tunnel service for the GUI Client, for both Linux and Windows.

It is built as:

  • headless-client to act as the Linux / Windows headless Client
  • firezone-headless-client to act as the Linux tunnel service, Windows headless Client, or Windows tunnel service

In general, the brand name should be part of the file name, but the OS name should not be.

Running

To run the headless Client:

  1. Generate a new Service account token from the "Actors -> Service Accounts" section of the admin portal and save it in your secrets manager. The Firezone Linux client requires a service account at this time.
  2. Ensure /etc/dev.firezone.client/token is only readable by root (i.e. chmod 400)
  3. Ensure /etc/dev.firezone.client/token contains the Service account token. The Client needs this before it can start
  4. Set FIREZONE_ID to a unique string to identify this client in the portal, e.g. export FIREZONE_ID=$(head -c 32 /dev/urandom | sha256sum | cut -d' ' -f1). The client requires this variable at startup. We recommend this to be a 64 character hex string.
  5. Set LOG_DIR to a suitable directory for writing logs
    export LOG_DIR=/tmp/firezone-logs
    mkdir $LOG_DIR
    
  6. Now, you can start the client with:
./firezone-headless-client standalone

If you're running as an unprivileged user, you'll need the CAP_NET_ADMIN capability to open /dev/net/tun. You can add this to the client binary with:

sudo setcap 'cap_net_admin+eip' /path/to/firezone-headless-client

Building

Assuming you have Rust installed, you can build the headless Client with:

cargo build --release -p firezone-headless-client

The binary will be in target/release/firezone-headless-client

The release on Github are built with musl. To build this way, use:

rustup target add x86_64-unknown-linux-musl
sudo apt-get install musl-tools
cargo build --release -p headless-client --target x86_64-unknown-linux-musl

Files

  • /etc/dev.firezone.client/token - The service account token, provided by the human administrator. Must be owned by root and have 600 permissions (r/w by owner, nobody else can read) If present, the tunnel will ignore any GUI Client and run as a headless Client. If absent, the tunnel will wait for commands from a GUI Client
  • /usr/bin/firezone-headless-client - The tunnel binary. This must run as root so it can modify the system's DNS settings. If DNS is not needed, it only needs CAP_NET_ADMIN.
  • /usr/lib/systemd/system/firezone-headless-client.service - A systemd service unit, installed by the deb package.
  • /var/lib/dev.firezone.client/config/firezone-id - The device ID, unique across an organization. The tunnel will generate this if it's not present.