# Cilium Host Firewall Policy Audit Mode Testing

## Overview

This guide explains how to test Cilium host firewall policies in audit mode before applying them in enforcement mode. This prevents accidentally locking yourself out of the cluster.

## Prerequisites

- `kubectl` configured and working
- Access to the cluster (via Tailscale or direct connection)
- Cilium installed and running

## Quick Start

Run the automated test script:

```bash
./tools/test-cilium-policy-audit.sh
```

This script will:
1. Find the Cilium pod
2. Locate the host endpoint (identity 1)
3. Enable PolicyAuditMode
4. Start monitoring policy verdicts
5. Test basic connectivity
6. Show audit log entries

## Manual Testing Steps

### 1. Find Cilium Pod

```bash
kubectl -n kube-system get pods -l "k8s-app=cilium"
```

### 2. Find Host Endpoint

The host endpoint has identity `1`. Find its endpoint ID:

```bash
CILIUM_POD=$(kubectl -n kube-system get pods -l "k8s-app=cilium" -o jsonpath='{.items[0].metadata.name}')
kubectl exec -n kube-system ${CILIUM_POD} -- \
  cilium endpoint list -o jsonpath='{[?(@.status.identity.id==1)].id}'
```

### 3. Enable Audit Mode

```bash
kubectl exec -n kube-system ${CILIUM_POD} -- \
  cilium endpoint config <ENDPOINT_ID> PolicyAuditMode=Enabled
```

### 4. Verify Audit Mode

```bash
kubectl exec -n kube-system ${CILIUM_POD} -- \
  cilium endpoint config <ENDPOINT_ID> | grep PolicyAuditMode
```

Should show: `PolicyAuditMode : Enabled`

### 5. Start Monitoring

In a separate terminal, start monitoring policy verdicts:

```bash
kubectl exec -n kube-system ${CILIUM_POD} -- \
  cilium monitor -t policy-verdict --related-to <ENDPOINT_ID>
```

### 6. Test Connectivity

While monitoring, test various connections:

**Kubernetes API:**
```bash
kubectl get nodes
kubectl get pods -A
```

**Talos API (if talosctl available):**
```bash
talosctl -n <NODE_IP> time
talosctl -n <NODE_IP> version
```

**Cluster Internal:**
```bash
kubectl get services -A
```

### 7. Review Audit Log

Look for entries in the monitor output:
- `action allow` - Traffic allowed by policy
- `action audit` - Traffic would be denied but is being audited (not dropped)
- `action deny` - Traffic denied (only in enforcement mode)

### 8. Disable Audit Mode (When Ready)

Once you've verified all necessary traffic is allowed:

```bash
kubectl exec -n kube-system ${CILIUM_POD} -- \
  cilium endpoint config <ENDPOINT_ID> PolicyAuditMode=Disabled
```

## Expected Results

With the current policies, you should see `action allow` for:

1. **Kubernetes API (6443)** from:
   - Tailscale network (100.64.0.0/10)
   - VLAN subnet (10.132.0.0/24)
   - VIP (<VIP_IP>)
   - External IPs (152.53.x.x)
   - Cluster entities

2. **Talos API (50000, 50001)** from:
   - Tailscale network
   - VLAN subnet
   - VIP
   - External IPs
   - Cluster entities

3. **Cluster Internal Traffic** from:
   - Cluster entities
   - Remote nodes
   - Host

## Troubleshooting

### No Policy Verdicts Appearing

- Ensure PolicyAuditMode is enabled
- Check that policies are actually applied: `kubectl get ciliumclusterwidenetworkpolicies`
- Generate more traffic to trigger policy evaluation

### Seeing `action audit` (Would Be Denied)

This means traffic would be blocked in enforcement mode. Review your policies and add appropriate rules.

### Locked Out After Disabling Audit Mode

If you lose access after disabling audit mode:

1. Use the Hetzner Robot firewall escape hatch (if configured)
2. Or access via Tailscale network (should still work)
3. Re-enable audit mode via direct node access if needed

## Policy Verification Checklist

Before disabling audit mode, verify:

- [ ] Kubernetes API accessible from Tailscale
- [ ] Kubernetes API accessible from VLAN
- [ ] Talos API accessible from Tailscale
- [ ] Talos API accessible from VLAN
- [ ] Cluster internal communication working
- [ ] Worker nodes can reach control plane
- [ ] No unexpected `action audit` entries for critical services

## References

- [Cilium Host Firewall Documentation](https://docs.cilium.io/en/stable/policy/language/#host-firewall)
- [Policy Audit Mode Guide](https://datavirke.dk/posts/bare-metal-kubernetes-part-2-cilium-and-firewalls/#policy-audit-mode)
- [Cilium Network Policies](https://docs.cilium.io/en/stable/policy/language/)