SSH MCP Server

Hardened SSH operations for VS Code Copilot Chat via the Model Context Protocol

Features • Quick Start • Tools • Configuration • Security • Testing • Contributing

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What Is This?

SSH MCP Server lets you manage remote Linux servers through natural language in VS Code Copilot Chat. Instead of switching to a terminal and remembering SSH commands, you just ask:

"Check disk usage on production-web"

"Show me the last 200 lines of /var/log/nginx/error.log on staging"

"Download /var/log/syslog from web-server-01 for incident INC-2026-0309"

The server enforces strict security policies — no raw shell access, all commands go through pre-approved templates, parameters are regex-validated, secrets in output are auto-redacted, and privileged operations require an approval workflow.

Features

• 23 MCP tools — host discovery, session management, command execution (sync + background), file transfer, SFTP operations, SSH key management, certificate lifecycle, approval workflows
• Template-only execution — no raw shell; every command matches a registered template with regex-validated parameters
• 3-tier security model — read-only (Tier 0), controlled mutation with confirmation (Tier 1), privileged with approval workflow (Tier 2)
• Automatic secret redaction — AWS keys, bearer tokens, passwords, private keys are scrubbed from output
• Tamper-evident audit log — every operation is logged with hash-chain integrity verification
• Short-lived SSH certificates — issue and revoke certificates with TTL enforcement via a local CA
• Persistent SSH sessions — connection pooling with keepalive probes and configurable idle timeout
• Background command execution — run long-running template commands asynchronously with output polling
• Path traversal protection — .. sequences blocked in all path parameters and file transfers
• Transfer policy — allowed paths, blocked extensions, size limits, mandatory justification for downloads

Quick Start

Prerequisites

• Python 3.11+
• VS Code with GitHub Copilot extension
• SSH access to at least one remote Linux host

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Install

As vscode plugin

Follow instructions on link:

https://marketplace.visualstudio.com/items?itemName=bhayanak.ssh-mcp-server-secure

Python package: https://pypi.org/project/ssh-mcp-server-copilot/

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Install from Source (for development / contributing)

git clone https://github.com/bhayanak/ssh-mcp-server.git
cd ssh-mcp-server

python -m venv .venv
source .venv/bin/activate   # macOS/Linux
# .venv\Scripts\activate    # Windows

pip install -e ".[dev]"

For local development, create .vscode/mcp.json pointing to the local source:

{
  "servers": {
    "ssh-mcp": {
      "type": "stdio",
      "command": "${workspaceFolder}/.venv/bin/python",
      "args": ["-m", "ssh_mcp.server"],
      "env": {
        "SSH_MCP_CONFIG_DIR": "${workspaceFolder}/config",
        "SSH_MCP_HOSTS_FILE": "${workspaceFolder}/config/hosts.json",
        "SSH_MCP_TEMPLATES_FILE": "${workspaceFolder}/config/templates.json",
        "SSH_MCP_AUDIT_LOG_DIR": "${workspaceFolder}/audit_logs",
        "SSH_MCP_CERT_DATA_DIR": "${workspaceFolder}/cert_data",
        "SSH_MCP_APPROVAL_DATA_DIR": "${workspaceFolder}/approval_data",
        "SSH_MCP_SSH_KNOWN_HOSTS_FILE": "~/.ssh/known_hosts"
      }
    }
  }
}

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Configure Your Hosts

Edit the hosts file with your actual servers. If you used ssh-mcp-server-copilot init, edit ~/.ssh-mcp/hosts.json. If developing from source, edit config/hosts.json.

[
  {
    "host_id": "my-server",
    "hostname": "192.168.1.10",
    "port": 22,
    "ssh_user": "deploy",
    "labels": {"env": "production", "role": "web"},
    "description": "Production web server",
    "allowed_roles": ["operator", "admin"]
  }
]

Field	Required	Description
host_id	Yes	Unique identifier (alphanumeric, dots, dashes)
hostname	Yes	IP address or FQDN
port	No	SSH port (default: 22)
ssh_user	Yes*	Remote SSH username. If empty, uses your OS username
labels	No	Key-value tags for organization
description	No	Human-readable description
allowed_roles	No	Which roles can access this host (default: operator, admin)

Set Up SSH Access

Your SSH key must be authorized on each host:

# Generate a key if you don't have one
ssh-keygen -t ed25519 -C "your-email@example.com"

# Copy to each host
ssh-copy-id -i ~/.ssh/id_ed25519.pub deploy@192.168.1.10

# Load into ssh-agent (required — the MCP server uses the agent)
eval "$(ssh-agent -s)"
ssh-add ~/.ssh/id_ed25519

# Verify access
ssh deploy@192.168.1.10 "echo OK"

Add host keys to known_hosts:

ssh-keyscan -H 192.168.1.10 >> ~/.ssh/known_hosts

Start Using

1. Open the workspace in VS Code
2. The MCP server auto-starts from .vscode/mcp.json
3. Open Copilot Chat (Cmd+Shift+I / Ctrl+Shift+I)
4. Switch to "Agent" mode (critical — only Agent mode can invoke MCP tools)
5. Verify tools are loaded — click the tools icon in the chat input bar, you should see 23 tools from ssh-mcp

Now just ask in natural language:

> List all my SSH hosts
> Check disk usage on my-server
> Show me the last 100 lines of /var/log/syslog on my-server
> What's the status of nginx on my-server?

Tools (23)

Tier 0 — Read-Only (No Confirmation)

Tool	Description
list_hosts	List all configured SSH hosts with labels and metadata
get_host_facts	Get OS, uptime, kernel info from a host
get_audit_logs	View the tamper-evident audit trail
list_templates	List available command templates
list_pending_approvals	View pending approval requests

Session Management

Tool	Description
ssh_connect	Open a persistent SSH session (returns session_id for reuse)
ssh_disconnect	Close a persistent session
ssh_list_sessions	List active sessions and remaining connection slots
ssh_session_ping	Health-check a session (liveness, idle time, uptime)

Tier 1 — Controlled Mutation (Confirmation Required)

Tool	Description
run_ssh_command	Execute a template command on a host (supports session_id for persistent connections)
transfer_file	Download/upload files via SFTP with path and extension policies (supports session_id)

Background Command Execution

Tool	Description
run_ssh_command_background	Start a template command in the background (returns job_id)
poll_background_job	Read accumulated stdout/stderr of a background job (redacted)
list_background_jobs	List all background jobs (running + completed)
cancel_background_job	Cancel a running background job

Enhanced SFTP

Tool	Description
sftp_list_directory	List files in a remote directory (within allowed paths)
sftp_delete	Delete a remote file (within allowed paths, requires justification)

Tier 2 — Privileged (Approval Required)

Tool	Description
add_ssh_key	Register a public SSH key with TTL enforcement
remove_ssh_key	Revoke a registered SSH key
issue_cert	Issue a short-lived SSH certificate via the local CA
revoke_cert	Revoke a certificate and delete its PEM
request_approval / approve_request	Approval workflow for privileged ops

Configuration

Command Templates

Templates define which commands can be executed. Edit config/templates.json:

[
  {
    "template_id": "disk_usage",
    "description": "Show disk usage summary",
    "command": "df -h",
    "allowed_params": {},
    "allowed_roles": ["developer", "operator", "admin"],
    "timeout_seconds": 10,
    "risk_level": "low"
  },
  {
    "template_id": "tail_log",
    "description": "Tail the last N lines of a log file",
    "command": "tail -n {lines} {log_path}",
    "allowed_params": {
      "lines": "^[0-9]{1,5}$",
      "log_path": "^/var/log/[a-zA-Z0-9_./-]+$"
    },
    "allowed_roles": ["operator", "admin"],
    "timeout_seconds": 15,
    "risk_level": "low"
  }
]

Each parameter is validated against a regex pattern before substitution. Path traversal (..) is blocked automatically.

Environment Variables

All configuration is via environment variables with the SSH_MCP_ prefix:

Variable	Default	Description
SSH_MCP_CONFIG_DIR	~/.ssh-mcp	Base config directory (all other paths derive from this)
SSH_MCP_HOSTS_FILE	{config_dir}/hosts.json	Path to hosts configuration
SSH_MCP_TEMPLATES_FILE	{config_dir}/templates.json	Path to command templates
SSH_MCP_AUDIT_LOG_DIR	{config_dir}/audit_logs	Audit log directory
SSH_MCP_CERT_DATA_DIR	{config_dir}/cert_data	Certificate storage directory
SSH_MCP_APPROVAL_DATA_DIR	{config_dir}/approval_data	Approval data directory
SSH_MCP_MAX_SESSIONS	10	Max simultaneous SSH sessions
SSH_MCP_SESSION_IDLE_TIMEOUT	300	Idle session timeout (seconds)
SSH_MCP_KEEPALIVE_INTERVAL	15	SSH keepalive interval (seconds)
SSH_MCP_KEEPALIVE_COUNT_MAX	3	Max failed keepalive probes before disconnect
SSH_MCP_MAX_BACKGROUND_JOBS	10	Max concurrent background jobs
SSH_MCP_JOB_OUTPUT_MAX_BYTES	1048576	Max output buffer per background job (1 MB)
SSH_MCP_JOB_TTL_SECONDS	3600	Background job auto-expiry (1 hour)
SSH_MCP_SSH_KNOWN_HOSTS_FILE	(none)	Path to SSH known_hosts file
SSH_MCP_REQUIRE_TWO_PARTY_APPROVAL	true	Require different user as approver
SSH_MCP_AUTH_TOKEN	(none)	Bearer token (empty = dev mode)
SSH_MCP_SSH_TIMEOUT_SECONDS	30	SSH connection timeout

Transfer Policy (Defaults)

Setting	Default
Allowed paths	/tmp/*, /var/log/*
Blocked extensions	.exe, .sh, .bat, .ps1, .dll, .so
Max file size	50 MB
Require justification for downloads	Yes

Roles

Role	Access
developer	Read-only tools, low-risk commands
operator	All Tier 0 + Tier 1 tools
admin	All tools including Tier 2 (key/cert management)
auditor	Audit log access

Security

Design Principles

1. No raw shell — all commands go through registered templates
2. Parameter validation — every parameter is regex-validated before substitution
3. Path traversal blocking — .. sequences rejected in all parameters and file paths
4. Secret redaction — AWS keys, bearer tokens, passwords, private keys automatically scrubbed from output
5. Approval workflow — privileged operations (key/cert management) require explicit approval with HMAC-verified tokens
6. Tamper-evident audit — hash-chained audit log for forensic analysis
7. Strict host validation — paramiko RejectPolicy by default (no auto-accepting unknown hosts)
8. TTL enforcement — SSH certificates and keys have configurable maximum lifetimes

Approval Workflow

Tier 2 operations follow a 3-step flow:

1. request_approval  →  returns request_id + one-time approval_token
2. approve_request   →  verifies HMAC token, marks approved
3. call the tool     →  pass approval_request_id, consumed after use

With REQUIRE_TWO_PARTY_APPROVAL=true (production), a different user must approve.

Audit Log Verification

python -c "
from ssh_mcp.audit import AuditLogger
from pathlib import Path
logger = AuditLogger(Path('audit_logs'))
ok, msg = logger.verify_chain()
print(f'Chain integrity: {ok} — {msg}')
"

Testing

Unit Tests

# Run all tests
pytest tests/ -v

# With coverage
pytest tests/ -v --cov=ssh_mcp

Runtime Directories (git-ignored, auto-created)

Directory	Purpose
audit_logs/	Tamper-evident audit log (audit.jsonl)
cert_data/	CA keys, issued certificates, revocation list
approval_data/	Pending and consumed approval requests

CLI Reference

ssh-mcp-server-copilot --version          # Print version
ssh-mcp-server-copilot init               # Create ~/.ssh-mcp with default configs
ssh-mcp-server-copilot                    # Start MCP server (stdio transport)
ssh-mcp-server-copilot --config-dir PATH  # Use custom config directory
ssh-mcp-server-copilot --config-dir PATH init  # Init a custom config directory

Contributing

1. Fork the repository
2. Create a feature branch: git checkout -b feature/my-feature
3. Make your changes
4. Run tests: pytest tests/ -v
5. Lint: ruff check src/ tests/
6. Submit a pull request

License

MIT