Netcatty/resources/mosh

Bundled mosh-client

This directory holds the network-protocol-only mosh-client binary bundled with the Netcatty installer. Netcatty drives the ssh + mosh-server bootstrap itself and then launches this bundled client directly (see electron/bridges/moshHandshake.cjs and electron/bridges/terminalBridge.cjs).

How binaries land here

1. .github/workflows/build-mosh-binaries.yml builds or fetches mosh-client on relevant pushes/PRs, or on a manual workflow_dispatch. It uses scripts/build-mosh/build-linux.sh and scripts/build-mosh/build-macos.sh for Linux/macOS, and scripts/build-mosh/fetch-windows.sh for the pinned Windows binary:

   target	provenance
   linux-x64	upstream source, manylinux2014, static third-party deps + glibc
   linux-arm64	upstream source, manylinux2014, static third-party deps + glibc
   darwin-universal	upstream source, lipo arm64 + x86_64, macOS system dylibs only
   win32-x64	FluentTerminal-pinned standalone fallback, SHA256 pinned
   win32-arm64	(not built — Cygwin arm64 port not yet stable)

   The upstream Cygwin Windows build path was removed from the default workflow because the tested build clears the terminal but never renders remote output on Windows.

2. When manually dispatched with release_tag, that workflow publishes the binaries to the dedicated binaricat/Netcatty-mosh-bin repository. The release gets a tag like mosh-bin-1.4.0-1, with SHA256SUMS attached.

3. Release packaging runs scripts/resolve-mosh-bin-release.cjs before npm run fetch:mosh. It uses an explicit workflow input first, then the MOSH_BIN_RELEASE repository variable, then the latest non-draft mosh-bin-* GitHub Release from the dedicated binary repository. The fetch step pulls the binaries into resources/mosh/<platform-arch>/. For local packaging, set MOSH_BIN_RELEASE yourself before running the same fetch command. Override MOSH_BIN_OWNER / MOSH_BIN_REPO only when testing a different binary repository. electron-builder.config.cjs then copies the matching binary into Resources/mosh/mosh-client[.exe].

   Local dev uses the same binary path: npm run dev runs npm run fetch:mosh:dev first, which downloads the host platform's bundled mosh-client into this gitignored directory. Netcatty does not fall back to a system-installed mosh or mosh-client; if the bundled binary is missing, Mosh startup fails loudly instead of using whatever happens to be installed on the developer machine.

   Official Windows package builds currently ship x64 only for bundled Mosh coverage. Windows arm64 packaging should be added only after we have a tested standalone arm64 client.

The directory is otherwise empty (binaries are gitignored).

Licenses

• Mosh itself is licensed under GPL-3.0 (https://github.com/mobile-shell/mosh).
• Netcatty is GPL-3.0, so redistribution as part of the installer is permitted.
• The default Windows x64 binary is the FluentTerminal-pinned standalone mosh-client.exe from https://github.com/felixse/FluentTerminal @ commit bad0f85, pinned by SHA256 in scripts/fetch-mosh-binaries.cjs. The old Cygwin build path is intentionally not used for Windows releases while it reproduces the blank-screen runtime issue.
• Bundled/static deps (OpenSSL Apache-2.0, protobuf BSD-3-Clause, ncurses MIT) are compatible with GPL-3.0.

Reproducible build

To reproduce the binaries locally:

docker run --rm -v $PWD:/workspace -w /workspace \
  -e MOSH_REF=mosh-1.4.0 -e ARCH=x64 -e OUT_DIR=/workspace/out \
  quay.io/pypa/manylinux2014_x86_64 \
  bash scripts/build-mosh/build-linux.sh

For macOS the build needs an Xcode toolchain; see scripts/build-mosh/build-macos.sh.

Phase 2/3 — done in this PR

• electron/bridges/moshHandshake.cjs reimplements the upstream Mosh Perl wrapper in Node: parser + sniffer + command builders as pure functions.
• terminalBridge.startMoshSession runs the SSH bootstrap in a node-pty so password / 2FA / known-hosts prompts render naturally in the user's terminal, then swaps session.proc from the ssh PTY to a freshly-spawned mosh-client PTY when MOSH CONNECT is detected. Keystrokes that arrive after the swap go to mosh-client because writeToSession reads session.proc lazily.
• Mosh startup requires Netcatty's bundled mosh-client and a usable ssh client for the remote bootstrap. System-installed mosh / mosh-client binaries are intentionally ignored.
• Windows x64 currently ships the FluentTerminal-pinned standalone client because the upstream Cygwin bundle can blank after terminal initialization on Windows.

Roadmap

• Add Windows arm64 only after a tested standalone arm64 client is available.
• Make MOSH_REF track upstream release tags automatically.