mcpwall
iptables for MCP. Blocks dangerous tool calls, scans for secret leakage, logs everything. No AI, no cloud, pure rules.
Sits between your AI coding tool (Claude Code, Cursor, Windsurf) and MCP servers, intercepting every JSON-RPC message and enforcing YAML-defined policies.
Why
MCP servers have full access to your filesystem, shell, databases, and APIs. When an AI agent calls tools/call, the server executes whatever the agent asks — reading SSH keys, running rm -rf, exfiltrating secrets. There's no built-in policy layer.
mcpwall adds one. It's a transparent stdio proxy that:
- Blocks sensitive file access —
.ssh/,.env, credentials, browser data - Blocks dangerous commands —
rm -rf, pipe-to-shell, reverse shells - Scans for secret leakage — API keys, tokens, private keys (regex + entropy)
- Scans server responses — redacts leaked secrets, blocks prompt injection patterns, flags suspicious content
- Logs everything — JSON Lines audit trail of every tool call and response
- Uses zero AI — deterministic rules, no LLM decisions, no cloud calls
- Test rules without running the proxy —
mcpwall checkgives instant pass/fail on any tool call
