agentsec-gateway 0.1.1

Security gateway for MCP (Model Context Protocol) server connections

MCP Security Gateway

Security gateway that proxies MCP (Model Context Protocol) server connections with real-time scanning, audit logging, and policy enforcement.

Part of the AgentSec suite -- open-source security primitives for AI agents.

Install

pip install agentsec-gateway

Premium: Get IP reputation database, advanced data flow analytics, and multi-server policy orchestration at zazmatt.gumroad.com/l/hjpwk

Quick Start

# Patch .mcp.json to route all MCP servers through the gateway
mcp-gateway install

# That's it. All MCP traffic is now scanned and logged.

How It Works

Claude Code                MCP Gateway              MCP Server
    |                          |                         |
    |--- JSON-RPC request ---->|                         |
    |                          |-- scan for secrets ---->|
    |                          |-- scan for injections ->|
    |                          |-- log to audit trail -->|
    |                          |--- forward request ---->|
    |                          |                         |
    |                          |<--- response -----------|
    |                          |-- scan for leakage ---->|
    |                          |-- log to audit trail -->|
    |<--- forward response ----|                         |

The gateway wraps each MCP server command in .mcp.json so all stdio traffic passes through a transparent proxy. It scans for:

• Secret leakage -- API keys, tokens, passwords, PII in tool parameters
• Prompt injection -- attempts to override system instructions via tool arguments
• Path traversal -- ../etc/passwd, ~/.ssh/ style attacks
• Command injection -- shell metacharacters, subshell execution
• Data exfiltration -- secrets in server responses flowing back to Claude

CLI Reference

Command	Description
mcp-gateway install	Patch .mcp.json to route through gateway
mcp-gateway uninstall	Restore original .mcp.json
mcp-gateway proxy --server NAME -- CMD	Run as proxy (internal, called by patched config)
mcp-gateway scan	List configured servers and their status
mcp-gateway audit [-n 20] [--server NAME]	View audit log
mcp-gateway report	Generate security report (reputation + data flow)
mcp-gateway status	Show install status and server list

Configuration

Create .mcp-gateway/policy.yaml to define per-server policies:

servers:
  filesystem:
    allowed_tools: ["read_*", "list_*", "search_*"]
    blocked_tools: ["write_*", "delete_*"]
    max_calls_per_minute: 30
    data_classification: internal

  gmail:
    allowed_tools: ["gmail_search*", "gmail_read*"]
    blocked_tools: ["gmail_create_draft", "gmail_send*"]
    max_calls_per_minute: 10
    data_classification: confidential

Policy Fields

Field	Type	Default	Description
allowed_tools	list[str]	[] (all)	Glob patterns for allowed tools
blocked_tools	list[str]	[]	Glob patterns for blocked tools
max_calls_per_minute	int	60	Rate limit per server
data_classification	str	internal	public, internal, confidential

Security Features

• Secret scanning -- 23 pattern rules covering API keys, tokens, passwords, PII (SSN, credit cards)
• High-entropy detection -- Shannon entropy analysis catches unknown secret formats
• Prompt injection detection -- catches "ignore previous instructions", developer mode, system tag injection
• Path traversal detection -- blocks ../, /etc/passwd, ~/.ssh/ access attempts
• Command injection detection -- catches shell metacharacters, subshells, pipe-to-bash
• Tamper-proof audit log -- SHA-256 hash chain on every log entry
• Server reputation tracking -- trust scores degrade on violations
• Data flow monitoring -- per-server byte counting with anomaly detection

Architecture

Built on agentsec-core for scanning, policy, and audit primitives. Uses synchronous threading for the stdio proxy (no asyncio complexity).

Free vs Premium

Feature	Free (OSS)	Premium
Transparent MCP proxy	Yes	Yes
Secret scanning (23 patterns)	Yes	Yes
Prompt injection detection	Yes	Yes
Tamper-proof audit log	Yes	Yes
IP reputation database	--	Yes
Data flow analytics dashboard	--	Yes
Multi-server policy orchestration	--	Yes
Rate limiting with burst control	--	Yes
Priority support	--	Yes

Get Premium -- $10

Development

pip install -e ".[dev]"
pytest
ruff check .

License

MIT