Realssh MCP Server

SSH Real MCP Server

A Model Context Protocol (MCP) server that enables SSH remote command execution by delegating entirely to the system ssh binary. This means ssh-agent, ProxyCommand, ~/.ssh/config, jump hosts, and every other OS-level SSH feature work out of the box — no Node.js crypto, no native addons.

How it works

Instead of implementing the SSH protocol in Node.js, this server spawns ssh as a child process and pipes the output back to the MCP client. Authentication, key discovery, and connection routing are handled by your OS, exactly as if you ran ssh yourself in a terminal.

Requirements: ssh must be installed and available in PATH (standard on macOS and Linux).

Features

• Zero auth config — uses your existing ssh-agent, ~/.ssh/config, and key files automatically
• ProxyCommand / jump hosts — works natively, no special parameters needed
• Connectivity test — ssh_test tool to verify reachability before running commands
• Argument injection protection — host and username are validated before being passed to ssh
• Configurable timeout — commands are killed and an error is returned if they exceed the timeout
• Detailed results: stdout, stderr, and exit code

Installation

From npm

npm install -g @danielecr/realssh-mcp

From source

git clone https://github.com/danielecr/realssh-mcp.git
cd realssh-mcp
npm install
npm run build

VS Code / Copilot configuration

After installing the package globally, add the server to your MCP configuration. In VS Code, open the MCP config file via Command Palette → MCP: Open User Configuration and add:

{
  "servers": {
    "realssh": {
      "type": "stdio",
      "command": "realssh-mcp"
    }
  }
}

Then run MCP: List Servers to verify the server is active.

Tools

ssh_execute

Execute a command on a remote server via SSH.

Parameters:

• host (string, required): SSH server hostname or IP address
• command (string, required): Command to execute on the remote server
• username (string, optional): SSH username. Defaults to the current OS user
• port (number, optional): SSH server port (default: 22)
• timeout (number, optional): Command timeout in milliseconds (default: 30000)
• agentForward (boolean, optional): Enable SSH agent forwarding -A (default: false)
• extraArgs (string[], optional): Extra SSH arguments (e.g., ["-o", "StrictHostKeyChecking=no"])

Example:

{
  "host": "prod-web-01",
  "command": "df -h"
}

{
  "host": "192.168.1.100",
  "username": "deploy",
  "command": "systemctl status nginx"
}

ssh_test

Test SSH connectivity to a remote host (runs echo ok and checks the response).

Parameters:

• host (string, required): SSH server hostname or IP address
• username (string, optional): SSH username
• port (number, optional): SSH server port (default: 22)
• extraArgs (string[], optional): Extra SSH arguments

Host configuration

Hosts, aliases, jump hosts, and identity files are configured in ~/.ssh/config — not in the MCP server. This is intentional: the OS ssh binary reads that file natively.

Example ~/.ssh/config:

Host prod
    HostName prod.example.com
    User deploy
    ProxyJump bastion

Host bastion
    HostName bastion.example.com
    User admin
    IdentityFile ~/.ssh/bastion_ed25519

With the above config, "host": "prod" works with no extra parameters.

Security considerations

• Commands are executed on remote systems with the privileges of the SSH user — ensure proper access controls on the remote side.
• BatchMode=yes is set by default, preventing the ssh process from hanging on interactive prompts.
• Host and username inputs are validated to prevent SSH option injection.
• Command output may contain sensitive data; treat it accordingly.

License

MIT