CrapTrap Guide

CrabTrap × OpenClaw

Simplified Setup Guide | May 2026

What is CrabTrap?

CrabTrap is an open-source LLM-as-a-judge HTTP/HTTPS proxy built by Brex. It sits between your

OpenClaw agent and every external API call it makes - intercepting, evaluating, and either allowing or

blocking requests based on your security policy. No SDK changes or wrappers needed.

How It Works with OpenClaw

You set HTTP_PROXY and HTTPS_PROXY env vars in OpenClaw's environment to point at CrabTrap. Every outbound call (Slack, Gmail, GitHub, etc.) is intercepted. CrabTrap applies fast static rules first, then uses an LLM judge for anything ambiguous – then forwards or blocks the request in real time.

Prerequisites

• Docker & Docker Compose – Required to run CrabTrap + PostgreSQL
• OpenAI / Anthropic API Key – Used as the LLM judge
• OpenClaw running locally or on server – The agent whose traffic you want to secure
• curl + jq (optional) – Helpful for setup commands

Pull & Start CrabTrap

Run CrabTrap alongside PostgreSQL using Docker Compose

docker compose up -d

• This starts the proxy on port 8080 and the admin UI on port 8081.

Generate CA Certificate

Copy the generated TLS certificate authority from the container

docker compose cp crabtrap:/app/certs/ca.crt ./ca.crt

You'll need this certificate in every agent service that routes traffic through CrabTrap.

Create Admin User

Generate an admin token to access the web UI

admin_token=$(docker compose exec -it crabtrap ./gateway create-admin-user my-admin

\ | tail -n1 | cut -d" " -f2)

Create an Agent User & Get Gateway Token

Create a user for your OpenClaw agent and capture its gateway auth token:

token=$(curl -sX POST http://localhost:8081/admin/users \ -H "Content-Type:

application/json" \ -H "Authorization: Bearer ${admin_token}" \ -d '{"id": "openclaw@example.com", "is_admin": false}' \ | jq -r '.channels[] | select(.channel_type=="gateway_auth") | .gateway_auth_token')

Point OpenClaw at CrabTrap

In your OpenClaw environment config (e.g. .env or Docker environment block), add the following

variables

HTTP_PROXY=http://${token}:@localhost:8080
HTTPS_PROXY=http://${token}:@localhost:8080 SSL_CERT_FILE=/path/to/ca.crt

Replace ${token} with the actual token value from Step 4.

Test the Connection

Verify traffic is routing through CrabTrap

curl -x http://${token}:@localhost:8080 \ --cacert ca.crt https://httpbin.org/get

A successful response means CrabTrap is intercepting traffic correctly.

Set Your Security Policy

Open the admin UI at http://localhost:8081 and log in with your admin token. Use the Policy Builder to

either

• Write a natural-language policy (e.g. "Allow Slack and GitHub, block everything else")
• Click Bootstrap Policy to auto-generate one from observed traffic
• Run evals against past traffic before going live

Optional – Enforce Proxy-Only Traffic

For stronger security, add iptables rules in OpenClaw's container to block any direct outbound connections

that bypass the proxy

iptables -A OUTPUT -m owner --uid-owner agent-user -j DROP # Allow only traffic

going to CrabTrap proxy port iptables -I OUTPUT -m owner –uid-owner agent-user -d

localhost –dport 8080 -j ACCEPT

Architecture Overview

Component Role

Default Port

OpenClaw Agent

Your AI agent making API calls

–

CrabTrap Proxy

Intercepts & judges all traffic 8080

CrabTrap Admin UI

Policy config & traffic review 8081 PostgreSQL Stores audit logs & policies 5432

LLM Judge

Evaluates ambiguous requests

External API

Key Features

Per-IP Rate Limiting

Token bucket algorithm, no agent overload

Circuit Breaker

Trips after 5 consecutive LLM failures

Fallback Mode

Configurable: deny or passthrough when LLM unavailable

Policy Evals

Test policies against real traffic before deploying

No SDK Changes

Works via standard HTTP_PROXY env variables