Pylon v0.2.0

Changelog

[0.2.0] — 15.05.2026

Fixed

SSH Handshake [Session(-1)] Unable to exchange encryption keys on Windows

Root cause: libssh2-sys on Windows MSVC has two separate feature flags:

• vendored-openssl — compiles OpenSSL from source (was already set)
• openssl-on-win32 — tells libssh2 to use OpenSSL as its crypto backend (was missing)

Without openssl-on-win32, libssh2 always compiles with WinCNG (Windows Cryptography
Next Generation) as its backend, regardless of whether OpenSSL is present. WinCNG's
Diffie-Hellman key exchange implementation has been broken since Windows 10 v1903 (May 2019),
causing the server to close the connection mid-handshake. libssh2 surfaces this as
LIBSSH2_ERROR_SOCKET_NONE = -1 with the message "Unable to exchange encryption keys".

macOS was unaffected because non-Windows targets unconditionally use OpenSSL.

Fix (src-tauri/Cargo.toml):

ssh2 = { version = "0.9", features = ["vendored-openssl", "openssl-on-win32"] }

Adding openssl-on-win32 sets CARGO_FEATURE_OPENSSL_ON_WIN32 during the libssh2-sys build,
which switches the compile-time define from LIBSSH2_WINCNG to LIBSSH2_OPENSSL.

Additional hardening (all 4 handshake sites):

• Removed pre-handshake TCP set_read_timeout/set_write_timeout — once libssh2 owns the
  socket via set_tcp_stream, Winsock-level timeouts conflict with libssh2's internal I/O loop.
• Added sess.set_blocking(true) + sess.set_timeout(30_000) — proper libssh2-level
  30 s timeout that works correctly on both Windows and macOS.

Build requirement (Windows): Strawberry Perl must be in PATH for the vendored-openssl
build step that compiles OpenSSL from source. Install portable Perl to C:\strawberry-perl
and add C:\strawberry-perl\perl\bin and C:\strawberry-perl\c\bin to the system PATH.

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Host Key Policy settings not respected in Vault and Quick Connect

Problems:

1. ZVault quick-connect always showed "accept via Quick Connect first" regardless of the
   host key policy setting in Settings → Security.
2. There was no way to accept an unknown host key from ZVault without switching to Quick Connect.
3. The Advanced panel in Quick Connect hardcoded "Ask (known_hosts)" instead of showing
   the live policy value.

Fix:

• Added vault_accept_host_key_and_connect(credential_id, permanent) Rust command that
  performs a fresh TCP connect + handshake + optional known_hosts write + authentication
  using vault-stored credentials (secrets never leave the backend).
• VaultModal now reads hostKeyPolicy from the settings store on every vault connect:
  • auto-accept → silently calls vaultAcceptHostKeyAndConnect with permanent: false
  • strict → rejects immediately with an error toast
  • ask (default) → shows the same HostKeyModal used by Quick Connect, then calls
    vaultAcceptHostKeyAndConnect with the user's permanent/once choice
• ConnectModal advanced panel now reads and displays the live policy value.

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App icon not rendering in titlebar and lock screen on Windows

Problem: The custom titlebar, app lock screen, and settings panel all load /pylon-icon.png
via a root-relative URL. No public/ directory existed in the project, so Vite had no file
to serve at that path — the <img> broke in both dev and production builds.

Fix: Created public/pylon-icon.png (copied from src-tauri/icons/icon.png). Vite serves
the public/ directory verbatim at the root URL, so the existing /pylon-icon.png references
in TitleBar.tsx, AppLock.tsx, and SettingsPanel.tsx now resolve correctly in both modes.

---

Installer and bundle still named Pylon_0.1.0_* after version bump

Problem: src-tauri/tauri.conf.json still contained "version": "0.1.0". This is the file
the Tauri bundler reads when naming build artifacts (Pylon_0.1.0_x64-setup.exe,
pylon_0.1.0_x64_en-US.msi). Updating only package.json and Cargo.toml had no effect
on the installer names.

Fix: Bumped tauri.conf.json version to 0.2.0. Also updated the hardcoded v0.1 badge
in TitleBar.tsx to v0.2.

---

Rust compiler warning: unused variable mirror_perms in fs_watcher.rs

Problem: push_file_via_sftp in src-tauri/src/fs_watcher.rs:572 accepted a
mirror_perms: bool parameter that was never read (permission mirroring not yet implemented
for that path).

Fix: Renamed to _mirror_perms to explicitly mark the parameter as intentionally unused,
silencing the #[warn(unused_variables)] warning.

Pylon v0.1.0

Pylon

Cross-platform SSH and SFTP desktop client built with Tauri v2, Rust, and React.

License: GPL-3.0 | Version: 0.1.0 (beta) | Platforms: Windows, macOS, Linux

Pylon is in beta. The vault format and configuration schema may change between pre-release versions. Back up your vault before upgrading.

---

Download

→ zsync.eu/pylon

Windows, macOS (Apple Silicon + Intel), and Linux — all builds available on the website. No account required. Free and open source under GPL-3.0.

macOS: Not yet notarized. Right-click the .app → Open → confirm in the security dialog on first launch.

---

Screenshots

Files	Terminal

Sync	Transfers

Settings	ZVault

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Features

File Management

• Dual-pane browser: local filesystem on the left, remote SFTP on the right, resizable
• Multi-select with Shift+Click (range), Ctrl+Click (individual), Ctrl+A (all)
• Drag-and-drop upload and download between panes
• Context menu with full file operations
• Sortable columns (name, size, modified, permissions)
• Editable path bar (Ctrl+L), click-to-navigate breadcrumb, bookmarks
• File permission display (octal and rwx notation)
• Regex and fuzzy filter per pane
• Remote chmod editor

Transfer Engine

• Resume support: interrupted transfers restart from the last verified byte
• Atomic writes: files staged as .pylon_tmp_* and renamed on completion
• SHA-256 checksumming per transfer
• Real-time bytes/sec and ETA in the transfer drawer (Ctrl+T)
• Pause, resume, and retry controls per transfer
• Concurrent transfers (1–16, configurable)
• Optional per-transfer bandwidth limit (kbps)
• Recursive directory upload/download
• Overwrite policy: ask / overwrite all / skip all

SSH Terminal

• xterm.js with full VT100/ANSI, 256-color support
• Multiple terminal tabs per session, with tab rename
• Navigating the remote pane sends a cd command to the active terminal
• Command snippets toolbar (save frequently used commands as quick-launch buttons)
• Clickable URLs via xterm-addon-web-links
• Shell selection (bash, zsh, sh, fish) per connection

ZVault — Credential Manager

• AES-256-GCM encryption for all stored credentials
• Argon2id key derivation from master passphrase (m=64 MB, t=3, p=4)
• Unique random salt and nonce per vault; no pre-computation attacks apply
• Auto-lock after configurable idle timeout
• Decrypted credentials kept in memory only; never written to disk in plaintext
• SSH key path storage alongside passwords
• Full CRUD UI for managing stored profiles

Sync Watchers

• Watch a local directory and sync changes to a remote path over SFTP
• Powered by the notify crate (inotify / kqueue / ReadDirectoryChangesW)
• Only changed files are uploaded; unchanged files are skipped
• 100 ms debounce window to coalesce rapid saves
• Delete propagation: remote files are deleted when local files are removed
• Optional timestamp preservation (mtime mirrored to remote)
• Optional permission mirroring (chmod applied to remote)
• .syncignore file support (gitignore syntax); .gitignore is also respected
• Keep-on-disconnect: watchers can be paused rather than stopped when a session ends
• Configurable overwrite rules: always overwrite / new files only / update existing / confirm on overwrite / confirm all

Metadata Stripping

Strip privacy-sensitive metadata in-flight on upload, or on-demand via context menu.

Format	Stripped
JPEG / PNG / WebP / GIF	EXIF data (GPS, camera, serial, timestamps, thumbnails)
PDF	Author, creator, producer, keywords, XMP metadata

Enable globally in Settings → Security, or trigger per-file from the context menu.

Security

• SSH host key verification against ~/.ssh/known_hosts on every connection
• Changed host keys show a blocking warning dialog (configurable policy: ask / auto-accept / strict)
• SSH keepalive prevents silent session drops
• No telemetry; no outbound connections beyond what you explicitly initiate
• Tauri CSP configured in src-tauri/capabilities/default.json

Other

• Command palette (Ctrl+K)
• Activity log
• Keyboard shortcuts for all major actions
• Bookmarks for local and remote paths

---

Building

Prerequisites

Tool	Required version
Rust	stable ≥ 1.77
Node.js	≥ 20 LTS
pnpm	≥ 9

Linux — install WebKit2GTK and related system libraries:

# Debian / Ubuntu
sudo apt-get install -y libwebkit2gtk-4.1-dev libappindicator3-dev librsvg2-dev patchelf

# Fedora / RHEL
sudo dnf install webkit2gtk4.1-devel libappindicator-gtk3-devel librsvg2-devel

macOS — Xcode Command Line Tools:

xcode-select --install

Dev

pnpm install
pnpm tauri dev

Frontend only (no Rust compilation, faster iteration):

pnpm dev

Verbose Rust logging:

RUST_LOG=debug pnpm tauri dev

Release build

pnpm install
pnpm tauri build

Artifacts are placed in src-tauri/target/release/bundle/.

---

Keyboard Shortcuts

Global

Shortcut	Action
Ctrl+K	Command palette
Ctrl+N	New connection
Ctrl+T	Toggle transfer drawer
Ctrl+D	Disconnect active session

File browser

Shortcut	Action
F5	Refresh pane
Ctrl+A	Select all
Ctrl+L	Edit path bar
Enter	Open folder / download file
Backspace	Navigate up

Terminal

Shortcut	Action
Ctrl+Shift+T	New terminal tab
Ctrl+Shift+C	Copy selection
Ctrl+Shift+V	Paste

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Tech Stack

Frontend: React 18, TypeScript 5, Vite 5, Tailwind CSS 3, Zustand, Framer Motion, xterm.js 5, Lucide React, react-resizable-panels

Backend (Rust): tauri 2, ssh2, tokio, aes-gcm, argon2, notify, image, kamadak-exif, lopdf, sha2, ignore, rayon, flume, serde, anyhow, tracing

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Vault file location

Platform	Path
Linux	~/.config/pylon/vault-default.json
macOS	~/Library/Application Support/pylon/vault-default.json
Windows	%APPDATA%\pylon\vault-default.json

If you forget your master password there is no recovery mechanism. The vault cannot be decrypted without the correct passphrase.

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macOS note

Pylon is not yet notarized by Apple. On first launch, right-click the .app and choose Open, then confirm in the security dialog.

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License

GNU General Public License v3.0. See LICENSE.