TL;DR in plain English
- What this is: GateKeep402 is an open-source, deterministic socket-layer pre-payment audit proxy that aims to stop wallet-draining prompt injections and ghost paywalls. The project is described in the repo: https://github.com/al1-nasir/gatekeep402.
- What it does: it sits between an autonomous agent and payment endpoints to inspect low-level socket calls and make a reproducible decision to allow, block, or escalate before funds move. See the repo for the claim and examples: https://github.com/al1-nasir/gatekeep402.
- Quick proof step (concrete): clone the repo, run a local proxy bound to 127.0.0.1:8080, then exercise one allowed request and one blocked request to confirm deterministic decisions and an audit entry.
Methodology note: steps and numbers below are grounded in the repository description and typical PoC practice from the snapshot: https://github.com/al1-nasir/gatekeep402.
What you will build and why it helps
Concrete deliverable: a local PoC composed of one proxy process, one minimal policy file, and one audit log that records one allow and one block. Use https://github.com/al1-nasir/gatekeep402 as the implementation reference.
Why this matters:
- Single decision point reduces attack surface for payment flows (one place to enforce rules).
- Deterministic evaluation yields reproducible decisions for the same input + policy, aiding audits and tests.
- Typically low code impact: redirecting network traffic to the proxy is often enough.
Minimum concrete outputs (all tracked in git):
- 1 cloned repo: https://github.com/al1-nasir/gatekeep402
- 1 running proxy (example listen port: 8080)
- 1 policy file under version control (example tag v0.1)
- 1 audit log file with UTC timestamps and rule ids
Decision frame (comparison table):
| Decision | Typical latency impact | Use case | Example threshold | |---|---:|---|---:| | allow | +<50 ms median | sandbox/known wallet | 1% canary traffic start | block | 0–5 ms (reject fast) | unknown/unexpected charges | alert if >5 blocks/hour | escalate | +100–200 ms | require human review | pause if >24 hours persistent blocks
Reference: https://github.com/al1-nasir/gatekeep402
Before you start (time, cost, prerequisites)
Estimated time and cost:
- PoC time: ~90 minutes (range: 30–120 minutes depending on familiarity).
- Local cost: $0–$10 (run on laptop or small VM). Production costs vary by hosting and wallet sandboxing.
Machine and environment prerequisites:
- git access to clone https://github.com/al1-nasir/gatekeep402
- A machine (developer laptop or VM) with 1 CPU and ~1 GB free RAM for a local PoC
- Ability to open a local TCP port (example: 8080) and change an agent endpoint or apply DNS/firewall redirect
Pre-start checklist:
- [ ] Clone the repo: git clone https://github.com/al1-nasir/gatekeep402
- [ ] Reserve a test port (e.g., 8080) and ensure it is free
- [ ] Prepare or mock a payment endpoint (sandbox)
- [ ] Ensure you can redirect an agent to http://127.0.0.1:8080 or enforce egress controls
Reference: https://github.com/al1-nasir/gatekeep402
Step-by-step setup and implementation
Follow these condensed steps. Adapt commands to the repository binaries or containers: https://github.com/al1-nasir/gatekeep402.
- Clone and inspect
git clone https://github.com/al1-nasir/gatekeep402.git
cd gatekeep402
ls -la
# open README and example configs in the repository
- Run the proxy (example run)
If the repo provides a binary or script, use that. Examples below assume a binary named gatekeep402 and bind to port 8080.
# example: run a local proxy bound to 127.0.0.1:8080
./gatekeep402 --config ./config/example-policy.yaml --listen 127.0.0.1:8080
Or build and run a container if a Dockerfile exists:
docker build -t gatekeep402:local .
docker run -p 8080:8080 --name gatekeep402 gatekeep402:local
- Create a minimal policy file (illustrative)
Keep the policy narrow at first and store it in git so changes are auditable. Adapt the schema to the repo’s policy format. This example is illustrative and should be aligned to the repo's policy syntax: https://github.com/al1-nasir/gatekeep402.
# example-policy.yaml (illustrative template)
version: 1
rules:
- id: allow-sandbox-charge
match: "host == 'sandbox-pay.example' && path startsWith '/charge'"
action: allow
- id: block-all-others
match: "true"
action: block
audit:
enabled: true
log_level: info
- Point an agent or client at the proxy
- Change the agent’s payment endpoint to http://127.0.0.1:8080 or apply a DNS/firewall redirect.
- Test with one benign request and one crafted request that should be blocked.
- Test with curl
# benign test (small amount)
curl -v http://127.0.0.1:8080/charge -d '{"amount":1,"currency":"USD"}'
# crafted test that should be blocked (example amount: 1000)
curl -v http://127.0.0.1:8080/charge -d '{"command":"buy now","amount":1000}'
- Iterate
- Keep policy files in git and tag test runs (example tag: v0.1-poc).
- Send audit logs to a local file (example: ./logs/audit.log) or a logging service. Search by rule id and UTC timestamp.
See: https://github.com/al1-nasir/gatekeep402
Common problems and quick fixes
Problem: proxy won't start or port conflict (e.g., 8080 already used).
- Fix: pick a different port (e.g., 8081), or stop the conflicting service. Check with ss or lsof.
Problem: agent still calls the real endpoint.
- Fix: verify agent config. If needed, apply DNS override or egress firewall rules to prevent bypass.
Problem: too many false positives (legitimate payments blocked).
- Fix: widen the allow rule temporarily, add a targeted allow for the specific host/path, and run regression tests.
- Suggested rollout thresholds: start with a canary at 1% traffic; investigate if you see >5 blocked attempts/hour; pause if issues persist for 24 hours.
Problem: visibility is too low.
- Fix: increase log level to debug, add structured fields (rule id, decision, request hash), and index logs.
Quick troubleshooting checklist:
- [ ] Confirm proxy process is running and listening on chosen port
- [ ] Reproduce with curl and capture audit logs
- [ ] If needed, enable debug logs and re-run failing cases
Reference and issues: https://github.com/al1-nasir/gatekeep402
First use case for a small team
This section gives three time-boxed, safe steps for solo founders or teams of 1–3 people. Each step runs on a laptop or small VM. See the repo: https://github.com/al1-nasir/gatekeep402.
Actionable step 1 — Quick PoC (30–90 minutes)
- Clone the repo and run the proxy locally on port 8080.
- Execute one benign curl and one blocked curl. Commit the policy and tag the run (example: v0.1).
- Measure added latency. Target: median added latency <50 ms; alarm if median >100 ms.
Actionable step 2 — Minimal staging with mock wallet (1–3 hours)
- Start a mocked payment endpoint on a small VM or laptop on a non-standard port.
- Redirect agent traffic to the proxy and run a 10-request smoke test. Expect valid requests allowed and crafted attack vectors blocked.
- Retain audit logs for at least 7 days during initial staging.
Actionable step 3 — Safety gates and rescue plan (under 10 minutes to execute)
- Implement a manual kill-switch: a single command to stop the proxy or flip policy to safe mode (block-all or allow-only).
- Create an incident channel and a one-page playbook any team member can follow in under 10 minutes.
- Set alert thresholds: alert if >5 blocked attempts/hour or if the blocked ratio exceeds 5% over 60 minutes.
Artifacts to maintain:
- policy file — e.g., ./config/example-policy.yaml
- audit logs — e.g., ./logs/audit.log (UTC timestamps, rule id)
- test harness — e.g., ./tests/integration
Operational numbers to start with: canary at 1% → monitor for 72 hours; investigate if >5 blocks/hour; pause if suspicious for 24 hours.
Source: https://github.com/al1-nasir/gatekeep402
Technical notes (optional)
- The repo describes GateKeep402 as a deterministic socket-layer pre-payment audit proxy. Deterministic evaluation simplifies reproducible tests: identical inputs + policy → identical decision. See: https://github.com/al1-nasir/gatekeep402.
- Performance targets: median added latency <50 ms; if latency exceeds 100 ms under load, measure and scale horizontally (add nodes or place proxy closer to agents).
- Testing: unit-test the policy evaluator and run integration tests that assert identical inputs yield identical decisions. Version policy files and review changes on a cadence (example: every 30 days).
Reference: https://github.com/al1-nasir/gatekeep402
What to do next (production checklist)
Assumptions / Hypotheses
- Assumption: the repository https://github.com/al1-nasir/gatekeep402 contains the code and examples needed to run a local PoC and the description of a deterministic socket-layer pre-payment audit proxy.
- Hypothesis: deterministic socket-layer interception will block a majority of wallet-draining prompt-injection flows for typical autonomous agents; validate with staged threat-model tests (run a 100-request attack simulation and measure block rate).
- Numerical thresholds to tune during rollout: PoC = 90 minutes, test port = 8080, canary = 1% traffic, alert if >5 blocked attempts/hour, emergency pause if persistent blocks for 24 hours, policy review every 30 days, canary monitor = 72 hours, latency target <50 ms.
Risks / Mitigations
- Risk: false positives block legitimate payments. Mitigation: start in staging, use narrow allow lists, whitelist specific hosts/paths, and maintain an emergency rollback that takes <10 seconds to trigger.
- Risk: agents bypass proxy via hard-coded endpoints. Mitigation: enforce egress controls, DNS overrides, or firewall rules and audit outbound connections (use tools to detect >1 unexpected host per agent).
- Risk: added latency or throughput limits. Mitigation: measure added latency (target <50 ms median), scale horizontally if median latency >100 ms, and maintain capacity for peak QPS (define target QPS, e.g., 100–1,000 depending on load).
Next steps
- Store policy files in version control and require code review for policy changes; tag PoC runs (example tag: v0.1).
- Implement a canary rollout: start at 1% traffic, evaluate for 72 hours, then progress (10% → 50% → 100%) if metrics meet targets.
- Wire audit logs and alerts to an incident channel; set alert thresholds (example: >5 blocked attempts/hour or blocked ratio >5% over 60 minutes).
- Schedule policy reviews every 30 days and pull upstream updates from https://github.com/al1-nasir/gatekeep402.
Final quick-install checklist:
- [ ] Clone repo and run local PoC (goal: ~90 minutes)
- [ ] Create staged environment with a mocked wallet
- [ ] Implement feature flag + canary (1% → 100%)
- [ ] Add alerts for >5 blocks/hour and enable an emergency kill-switch
Canonical source and implementation details: https://github.com/al1-nasir/gatekeep402