# cygnus-ssh-mcp **Cross-platform SSH MCP server with 46 purpose-built tools for real server management by AI agents** [![PyPI version](https://img.shields.io/pypi/v/cygnus-ssh-mcp.svg)](https://pypi.org/project/cygnus-ssh-mcp/) [![Python](https://img.shields.io/pypi/pyversions/cygnus-ssh-mcp.svg)](https://pypi.org/project/cygnus-ssh-mcp/) [![License: GPL v3](https://img.shields.io/badge/License-GPLv3-blue.svg)](https://www.gnu.org/licenses/gpl-3.0) [![Tests](https://img.shields.io/badge/tests-145%2B%20passing-brightgreen.svg)]() *Give Claude, OpenCode, or any MCP-compatible AI assistant full control of your Linux, macOS, and Windows servers with 46 specialized tools* [Prerequisites](#prerequisites-ssh-on-your-target-servers) · [Installation](#installation) · [Quick Start](#quick-start) · [Features](#features) · [Documentation](https://cygnussystems.github.io/cygnus-ssh-mcp/)

--- > [!TIP] > **A note from the author:** I've been running this daily since April 2025 — over a > year now — to manage a dozen+ machines and devices, plus a Proxmox host running > 30+ containers, across a network tied together with Tailscale. It started as a > tool to solve my own problem, and it's saved me a huge amount of manual work ever > since. After a year of running it against Linux, I've since added support for > Windows, macOS, and other devices with reduced shells like BusyBox. I'm > open-sourcing it now because I think anyone running real infrastructure will find > it just as useful. This is a young *public* repo, but the tool behind it isn't new > or unproven — it's been battle-tested against my own servers for over a year. > > If you find it useful, a ⭐ star or a mention to someone who manages their own > infrastructure goes a long way for a project this new — thank you! --- ## Why cygnus-ssh-mcp? **cygnus-ssh-mcp is an MCP server - usable from Claude Desktop, Claude Code, OpenCode, or any other MCP-compatible client - that connects your AI assistant directly to your remote servers over SSH, exposing 46 purpose-built tools instead of one generic command-runner.** It turns natural-language requests into real systems administration - connecting by alias, editing files, managing background processes, handling sudo - across Linux, macOS, and Windows targets alike. Doing that properly means solving a pile of genuinely hard, per-platform problems that a naive `ssh` wrapper never has to face - and that this project hit and fixed the hard way, including: - Getting a *real* PID back from a Windows target, instead of a meaningless local channel number - Recovering the actual exit code when Win32-OpenSSH silently flattens it to `1` - Reading file contents via SFTP instead of `Get-Content`, because PowerShell's console encodes stdout in its OEM code page and corrupts anything non-ASCII - Killing a `sudo`'d background process without leaving its privileged child orphaned or blindly firing SIGKILL at the wrong PID None of this shows up until you actually run these tools against real Linux, macOS, and Windows targets under real conditions - which is exactly how every one of these was found and fixed here, not guessed at from documentation. | What you get | Basic SSH MCP | cygnus-ssh-mcp | |--------------|:-------------:|:--------------:| | Run commands | ✅ | ✅ | | Pre-configured hosts with aliases | ❌ | ✅ | | Sudo support (Linux/macOS) | Limited | ✅ | | Windows Server support | ❌ | ✅ | | Background task management | ❌ | ✅ | | Line-level file editing | ❌ | ✅ | | Command history with output | ❌ | ✅ | | Recursive directory operations | ❌ | ✅ | | Archive create/extract | ❌ | ✅ | | Full Unicode support | Varies | ✅ | Beyond Linux, macOS, and Windows, cygnus-ssh-mcp can also reach further - routers, NAS boxes, and other non-standard SSH targets connect too, via a `flex` platform type and a capability probe that detects what each device's shell can actually do. See [Connecting to Alternate Platforms](#connecting-to-alternate-platforms) below. > [!WARNING] > **Alternate-platform (`flex`) support is a work in progress.** It's been > verified against several real devices, but the space of routers/NAS/embedded > systems is huge - expect rough edges on hardware that hasn't been tried yet. ### Example agent tasks Ask your MCP-capable agent to: - "Check disk space, memory, uptime, and recent logs on my `web` host." - "Patch this remote config file safely and show me the diff." - "Upload this build artifact, extract it, and restart the service." - "Start this command in the background and fetch the output later." - "Inspect running processes on my Windows SSH host." --- ## Prerequisites: SSH on Your Target Servers cygnus-ssh-mcp connects over standard SSH - it doesn't provide SSH itself, so each server you want to manage needs an SSH server already installed and running. **Linux** - usually pre-installed on server distros; if not: ```bash sudo apt install openssh-server # Debian/Ubuntu sudo systemctl enable --now ssh ``` **macOS** - enable Remote Login in System Preferences → Sharing, or from the terminal: ```bash sudo systemsetup -setremotelogin on ``` **Windows** (Server 2019+, or Windows 10/11) - OpenSSH Server is an optional feature: ```powershell Add-WindowsCapability -Online -Name OpenSSH.Server~~~~0.0.1.0 Start-Service sshd Set-Service -Name sshd -StartupType 'Automatic' ``` See [Windows Support](docs/25-windows-support.md) for Windows Server 2016 and other edge cases. --- ## Installation Pick **one** of the two options below - they're independent tools that don't share storage, so commands from one won't see or affect what the other did. ### Option A: pip (a persistent install) ```bash pip install cygnus-ssh-mcp ``` Uninstalling or upgrading: ```bash pip uninstall cygnus-ssh-mcp pip install --upgrade cygnus-ssh-mcp ``` ### Option B: uvx (no install at all) > [!NOTE] > **What's `uvx`?** It's part of [`uv`](https://docs.astral.sh/uv/) (a fast Python > package manager) - `uvx ` downloads a package into a disposable, > isolated cache and runs it immediately, without installing it into your system > Python, a project, or anywhere `pip` can see. Nothing lingers afterward for you > to manage. It's the easiest option if you just want your MCP client to launch > this server without thinking about Python environments at all. ```bash uvx cygnus-ssh-mcp ``` There's nothing to "uninstall" - `uvx` re-resolves and re-fetches the latest version on every run anyway. To force a fresh fetch or clear its cache instead: ```bash uvx --refresh cygnus-ssh-mcp # force this run to ignore the cache uv cache clean # clear uv's entire package cache ``` If you want a `uvx`-style setup that *does* persist (so it doesn't re-fetch every time) and can be upgraded deliberately, use `uv tool install cygnus-ssh-mcp` instead - manage that with `uv tool uninstall cygnus-ssh-mcp` / `uv tool upgrade cygnus-ssh-mcp`. This is still separate from `pip` (Option A) - don't mix `pip` commands with anything set up via `uv`/`uvx`, they can't see each other. --- ## Quick Start ### 1. Add your hosts You don't need to create anything by hand - the first time the server starts, it automatically creates an empty host config file at `~/.mcp_ssh_hosts.toml` (secure `0o600` permissions) if nothing is there yet. Just open that file (or use `ssh_conn_add_host` from within your AI assistant) and add entries like: ```toml # Minimal (password auth) - only required fields ["user@server.example.com"] password = "your_password" port = 22 # With alias and sudo (most common setup) ["admin@production.example.com"] password = "your_password" port = 22 sudo_password = "sudo_pass" # optional: for use_sudo operations alias = "prod" # optional: connect by alias description = "Production server" # optional: for documentation # SSH key authentication ["deploy@staging.example.com"] keyfile = "~/.ssh/id_ed25519" port = 22 alias = "staging" # Windows Server (requires OpenSSH) ["administrator@winserver.example.com"] password = "your_password" port = 22 alias = "win-prod" ``` **Required fields:** `port` + (`password` OR `keyfile`) **Optional fields:** `alias`, `description`, `sudo_password`, `key_passphrase` `sudo_password` is optional if your account uses password auth - when omitted, the regular `password` is reused for `use_sudo` operations too. It's only required if your sudo password differs from your login password, or if you're using SSH key auth (`keyfile`) with no `password` field at all - in that case, either set `sudo_password` explicitly or configure passwordless sudo on the server. > [!TIP] > **Host file locations:** Default is `~/.mcp_ssh_hosts.toml`. Falls back to `./mcp_ssh_hosts.toml` if not found. > Use `--config /path/to/hosts.toml` for a custom location. If a file already exists > at whichever path is used, it is **never** overwritten or reset - auto-creation > only ever happens when nothing is there yet. > [!WARNING] > **Watch for hidden file extensions.** If you create this file yourself in Notepad > or TextEdit, Windows and macOS both hide known extensions by default - a file you > named `mcp_ssh_hosts.toml` can silently actually be saved as > `mcp_ssh_hosts.toml.txt`, and the server will never find it. Turn on "show file > extensions" in Explorer/Finder, or verify from a terminal: > `ls -la ~/.mcp_ssh_hosts.toml*` (macOS/Linux) or > `dir %USERPROFILE%\.mcp_ssh_hosts.toml*` (Windows) - either should show exactly > one file, with no extra extension after `.toml`. ### 2. Add to your MCP client Most MCP clients (Claude Desktop, Claude Code, OpenCode, Cursor, Cline, Windsurf, and others) use the same `mcpServers` JSON shape shown below - only the config file's name and location differ per client. Claude Desktop is used as the concrete example here; see the Claude Code note further down for one client that differs, or check your own client's docs for its config file's path. > [!WARNING] > **Python must be on `PATH` for `"command": "cygnus-ssh-mcp"` (below) to work at > all.** This is the most common reason an MCP client fails to start the server > (or the tool list never appears) - and with Python often installed in several > different places on one machine, it's easy to hit. Check first with: > ```bash > python --version # Windows/macOS/Linux > python3 --version # macOS/Linux, if the above isn't found > ``` > If that fails with "not recognized"/"command not found", Python isn't on `PATH` - > fix that first (reinstall Python with "Add to PATH" checked on Windows, or add it > to your shell profile), or work around it entirely by finding the full path to > the installed executable instead: `where cygnus-ssh-mcp` (Windows) or > `which cygnus-ssh-mcp` (macOS/Linux), then use that directly as `command`: > ```json > { > "mcpServers": { > "ssh": { > "command": "C:\\Users\\yourname\\AppData\\Local\\Programs\\Python\\Python312\\Scripts\\cygnus-ssh-mcp.exe", > "args": ["--config", "C:\\Users\\yourname\\.mcp_ssh_hosts.toml"] > } > } > } > ``` For Claude Desktop, edit `claude_desktop_config.json`: ```json { "mcpServers": { "ssh": { "command": "cygnus-ssh-mcp" } } } ``` Or with a custom hosts file location: ```json { "mcpServers": { "ssh": { "command": "cygnus-ssh-mcp", "args": ["--config", "/path/to/my_hosts.toml"] } } } ``` On Windows, use an absolute path with **escaped** backslashes (JSON needs `\\`, not a single `\`): ```json { "mcpServers": { "ssh": { "command": "cygnus-ssh-mcp", "args": ["--config", "C:\\Users\\yourname\\.mcp_ssh_hosts.toml"] } } } ``` **Using [Claude Code](https://claude.com/claude-code) instead of Claude Desktop?** It reads its own project-level `.mcp.json` file (in your project root) rather than `claude_desktop_config.json`, and its schema supports a couple of extra fields Desktop doesn't have: ```json { "mcpServers": { "cygnus_ssh": { "command": "cygnus-ssh-mcp", "args": ["--config", "/path/to/.mcp_ssh_hosts.toml"], "working_dir": "/path/to/your/project", "auto_start": true } } } ``` - **`working_dir`** - the directory the server process runs from. Claude Desktop has no equivalent - it doesn't expose a configurable working directory at all, which is exactly why the Desktop examples above always use absolute paths. - **`auto_start`** - whether Claude Code starts this server automatically. Claude Desktop always auto-starts every configured server; there's no toggle for it. Everything else - the `--config` argument, and the PATH/backslash caveats from the warning above - applies the same way to both clients. ### 3. Start managing servers > [!NOTE] > `PROD` in the examples below is just an example **alias** (`alias = "prod"` in the > hosts file from step 1) - it's not a magic name. If a host doesn't have an alias > configured, refer to it by its full `user@host` key instead, e.g. "Connect to > admin@203.0.113.10 and..." or "Connect to deploy@myserver.example.com and...". > > Depending on which LLM/client you're using, it may not automatically realize it > should reach for this MCP server - if it tries to answer without connecting, or > claims it can't access remote servers, explicitly tell it to use the SSH MCP > tools (e.g. "use the ssh MCP to connect to PROD and..."). Just say: > "Connect to PROD and tell me about the machine - hardware, status, everything" > "Connect to the GPU box and tell me how many graphics cards it has and how much > total VRAM" > "Edit /etc/nginx/nginx.conf and change worker_connections to 2048" > "Find all .log files larger than 100MB in /var/log" It handles multi-step jobs just as easily - install packages, edit configs, open firewall ports, and restart services, all in one request: > "Install PostgreSQL, set it to listen on all interfaces, add a pg_hba.conf rule > for remote connections, open port 5432 in the firewall, and create a database > called analytics" > "Set up a full LAMP stack, download the latest WordPress, configure > wp-config.php with a new database, and get the site running at > /var/www/wordpress" > "Get a Let's Encrypt certificate for example.com, configure nginx to serve it > over HTTPS, and redirect all HTTP traffic to it" > "My Node app in /opt/api keeps crashing - check the logs, find out why, and set > it up as a systemd service that restarts automatically" > "Audit PROD's security - check what ports are open, what's actually listening on > them, whether the firewall rules match, and flag anything that looks like it > shouldn't be exposed to the internet" --- ## Platform Support cygnus-ssh-mcp works from **any client** (Windows, Linux, macOS) to **any target server**:

| From (Client) | To (Target) | Status | |---------------|-------------|--------| | Windows | Linux | ✅ Tested | | Windows | Windows | ✅ Tested | | Linux | Linux | ✅ Tested | | Linux | Windows | ✅ Tested | | macOS | Any | ✅ Supported | **Windows targets** require OpenSSH Server installed and running. --- ## Connecting to Alternate Platforms > [!WARNING] > **This is a work in progress.** It's been verified against several real > devices below, but routers/NAS/embedded systems vary enormously - expect to > hit devices that don't work yet, and please open an issue if you do. Beyond Linux, macOS, and Windows, cygnus-ssh-mcp connects to **any SSH target that responds to a basic shell command** - routers, NAS boxes, BSD-kernel appliances, and other embedded Linux devices. These report `os_type: "flex"`. On connect, a one-time capability probe checks the specific shell/coreutils features this project's tools depend on (GNU `find -printf`, `stat -c`, `du -sb`, `tar --strip-components`, `ps -o pgid=`, `xargs -0`, and more) - many embedded/BusyBox-based devices only support a smaller flag set than full GNU coreutils. The results come back from `ssh_conn_connect` as `capabilities` and, for anything missing, `capability_warnings`. A tool that needs a missing capability fails with a clear error naming exactly what's unavailable and, where one exists, a concrete fallback - nothing silently degrades. **Verified against:** | Device | Result | |---|---| | Alpine Linux (BusyBox) | Connects as `linux`; no `bash`/GNU `find`/`ps -o pgid=` - gated tools fail with clear fallback messages, everything else works | | OpenWrt | Connects as `linux`; root-only, most GNU extensions absent | | FreeBSD | Connects as `flex`; no `bash` by default, sudo/task tooling adapted to use `sh` | | Synology DSM (NAS) | Connects as `linux`; full GNU coreutils and working `sudo` - behaves like a normal Linux server | **Known limitation:** some devices reject SSH shell access entirely for an account, even one with admin-level permissions - this shows up as every command (even a bare `echo`) failing immediately after a successful login. No capability probe can fix that; `ssh_conn_connect` explains the situation in that failure rather than a generic error. Full details, capability list, and current gaps: [docs/26-alternate-platforms.md](docs/26-alternate-platforms.md). --- ## Features ### Host Configuration Stop typing credentials. Connect by alias. ```toml ["admin@server.com"] password = "secret" port = 22 alias = "web" ``` Then just: *"Connect to WEB"* Supports **password**, **SSH key**, and **encrypted keys with passphrase**. Update a field on an existing host without losing the rest (`ssh_host_update`), or switch every host tool to an alternate config file for the session (`ssh_host_use_config`) - handy for keeping separate host lists per project or environment. --- ### Line-Level File Editing Edit config files with surgical precision—no download/upload needed. ```python # Replace a single line ssh_file_replace_line( file_path="/etc/nginx/nginx.conf", match_line="worker_connections 1024;", new_line="worker_connections 4096;" ) # Insert lines after a match ssh_file_insert_lines_after_match( file_path="/etc/hosts", match_line="# Custom entries", lines_to_insert=["192.168.1.10 app.local", "192.168.1.11 db.local"] ) ``` **Safety built-in**: Operations fail if the match isn't unique—no accidental mass edits. --- ### Background Task Management Launch long-running processes and check back later. ```python # Start a backup (returns immediately) ssh_task_launch(command="./backup.sh", stdout_log="/var/log/backup.log") # Check status anytime ssh_task_status(pid=12345) # → 'running' or 'exited' # Kill if needed ssh_task_kill(pid=12345, force=True) ``` --- ### Comprehensive Sudo Support Every tool supports `use_sudo`. Password is handled automatically. ```python ssh_file_write(file_path="/etc/app/config.yaml", content="...", use_sudo=True) ssh_dir_mkdir(path="/opt/myapp", use_sudo=True) ssh_archive_extract(archive_path="/backup.tar.gz", destination_path="/", use_sudo=True) ``` --- ### Three-Way Timeout System Never get stuck on a hanging command - and never lose track of a long one either. ```python ssh_cmd_run( command="./long_script.sh", io_timeout=60.0, # Check back in if silent for 60s (does NOT kill it) wait_timeout=20.0, # Or check back in every 20s regardless of activity runtime_timeout=3600.0 # Hard safety cap - the only one that actually kills it ) ``` `io_timeout` and `wait_timeout` never kill the remote command - they hand off to background monitoring so you can check back later (`ssh_cmd_check_status`), read output collected so far (`ssh_cmd_output`), or decide to end it early (`ssh_cmd_kill`). Only `runtime_timeout` ever terminates anything. --- ### Full Unicode Support Write and read files with emojis, international text, and special characters—on **all platforms**. ``` ✅ ❌ 🎉 • → ≥ ∞ │ ┌ ─ 你好 مرحبا Привет café naïve ``` **How it works:** `ssh_file_read` and `ssh_file_write` use SFTP for direct binary transfer, completely bypassing shell encoding issues. This means Unicode works perfectly even on Windows targets where PowerShell's console encoding would normally corrupt special characters. --- ### Windows Server Support Full support for Windows targets with OpenSSH Server: - **PowerShell & CMD** command execution - **Windows path handling** (backslashes, drive letters, UNC paths) - **Administrator detection** — shows if session has elevated privileges - **SFTP-based file operations** — Unicode-safe, no encoding issues Note: `use_sudo` is ignored on Windows (no sudo equivalent). For elevated operations, connect with an Administrator account. --- ### And Much More... - **Command history** with output retention and pattern filtering - **Recursive directory operations**: search, copy, delete with dry-run - **Archive operations**: create and extract tar.gz - **System info**: OS version, memory, disk, CPU, uptime - **Pattern search**: regex and plain text in files - **Alternate host config files**: switch host lists per project/environment without restarting --- ## All 46 Tools ### Connection & Host Management (12 tools) | Tool | Description | |------|-------------| | `ssh_conn_connect` | Connect using pre-configured host (by key or alias) | | `ssh_conn_is_connected` | Check if SSH connection is active | | `ssh_conn_status` | Get connection status (user, host, OS, cwd) | | `ssh_conn_host_info` | Get detailed system information | | `ssh_conn_verify_sudo` | Verify sudo access | | `ssh_conn_add_host` | Add new host to configuration | | `ssh_host_list` | List all configured hosts | | `ssh_host_update` | Update fields on an existing host (rotate password, change port, etc.) in place | | `ssh_host_remove` | Remove host from configuration | | `ssh_host_use_config` | Switch to an alternate host config file for the session | | `ssh_host_disconnect` | Disconnect current session | | `list_tools` | List all available tools | ### Command Execution (6 tools) | Tool | Description | |------|-------------| | `ssh_cmd_run` | Execute command with I/O, wait, and runtime timeouts | | `ssh_cmd_kill` | Terminate running command | | `ssh_cmd_check_status` | Check command status | | `ssh_cmd_output` | Retrieve output from command | | `ssh_cmd_history` | Get command history with filtering | | `ssh_cmd_clear_history` | Clear command history | ### Background Tasks (3 tools) | Tool | Description | |------|-------------| | `ssh_task_launch` | Launch command in background | | `ssh_task_status` | Check if task is running | | `ssh_task_kill` | Send signal to task | ### File Operations (12 tools) | Tool | Description | |------|-------------| | `ssh_file_stat` | Get file metadata | | `ssh_file_read` | Read file contents via SFTP (Unicode-safe) | | `ssh_file_write` | Create/overwrite/append file | | `ssh_file_copy` | Copy file | | `ssh_file_move` | Move or rename file | | `ssh_file_transfer` | Upload or download files | | `ssh_file_find_lines_with_pattern` | Search for pattern in file | | `ssh_file_get_context_around_line` | Get context around match | | `ssh_file_replace_line` | Replace single line | | `ssh_file_replace_line_multi` | Replace with multiple lines | | `ssh_file_insert_lines_after_match` | Insert lines after match | | `ssh_file_delete_line_by_content` | Delete line by content | ### Directory Operations (11 tools) | Tool | Description | |------|-------------| | `ssh_dir_mkdir` | Create directory | | `ssh_dir_remove` | Remove directory | | `ssh_dir_list_files_basic` | Basic directory listing | | `ssh_dir_list_advanced` | Recursive listing with metadata | | `ssh_dir_search_glob` | Search files by pattern | | `ssh_dir_search_files_content` | Search text in files | | `ssh_dir_calc_size` | Calculate directory size | | `ssh_dir_delete` | Delete with dry-run support | | `ssh_dir_batch_delete_files` | Batch delete by pattern | | `ssh_dir_copy` | Copy directory recursively | | `ssh_dir_transfer` | Upload or download whole directories (archive-based) | ### Archive Operations (2 tools) | Tool | Description | |------|-------------| | `ssh_archive_create` | Create tar.gz archive | | `ssh_archive_extract` | Extract archive | --- ## Documentation **Full docs site: [cygnussystems.github.io/cygnus-ssh-mcp](https://cygnussystems.github.io/cygnus-ssh-mcp/)** — searchable, with navigation. Or browse the raw files directly in [docs/](docs/): - [Overview](docs/10-overview.md) - [Installation](docs/15-installation.md) - [Platform Compatibility](docs/20-platform-compatibility.md) - [Windows Support](docs/25-windows-support.md) - [Alternate Platforms (flex)](docs/26-alternate-platforms.md) - [Host Configuration](docs/30-host-configuration.md) - [Tools Reference](docs/40-tools-reference.md) - [Command Execution](docs/50-command-execution.md) - [Process Management](docs/60-process-management.md) - [Logging](docs/70-logging.md) - [Claude Desktop Setup](docs/80-claude-desktop.md) --- ## Use Cases - **DevOps Automation** — Deploy, configure, and manage servers via AI - **Log Analysis** — Search and analyze logs across multiple servers - **Configuration Management** — Edit configs with precision line operations - **Backup & Recovery** — Create archives, transfer files, restore backups - **System Monitoring** — Check status, verify services, monitor processes - **Security Auditing** — Search for sensitive patterns, verify configurations --- ## License [GPL-3.0](LICENSE) — Free and open source. ---

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