diff --git a/.planning/ROADMAP.md b/.planning/ROADMAP.md
index 6369118..8e69231 100644
--- a/.planning/ROADMAP.md
+++ b/.planning/ROADMAP.md
@@ -13,7 +13,9 @@ None
 - ✅ **Phase 1: Foundation Setup** - Establish core NixOS configuration with flakes
 - ✅ **Phase 2: Docker Service Integration** - Integrate Docker Compose services
 - ✅ **Phase 3: AI Assistant Integration** - Enable AI-assisted infrastructure management
-- [ ] **Phase 4: Internet Access & MCP** - MCP server for web access
+- ✅ **Phase 4: Internet Access & MCP** - MCP server for web access
+- 🚨 **Security Hardening** - CRITICAL: Firewall, fail2ban, SSH hardening (PR #28)
+- [ ] **Phase 5: TAK Server** - Research, implementation, and validation
 
 
 ## Phase Details
@@ -133,8 +135,25 @@ Plans:
 
 ## Progress
 
+**Merge Priority Order** (CRITICAL - merge in this order):
+
+| Priority | PR | Description | Status | Notes |
+|----------|-----|-------------|--------|-------|
+| 🚨 1 | #28 | **Security hardening** (firewall, fail2ban, SSH) | Open | **MERGE FIRST** - protects all other services |
+| 2 | #22 | Matrix bridge dependency fix | Open | Blocks Hermes functionality |
+| 3 | #21 | Backup network creation fix | Open | Infrastructure fix |
+| 4 | #25 | Hermes voice GPU support | Open | Feature enhancement |
+| 5 | #24 | uConsole CM5 host | Open | New hardware support |
+| 6 | #23 | NixOS deployment infrastructure | Open | Deployment tooling |
+| 7 | #1 | AI worker restricted access | Open | Legacy PR (superseded by hardening) |
+
 **Execution Order:**
-Phases execute in numeric order: 1 → 2 → 3 → 4 → 5 → 6 → 7
+Phases execute in numeric order: 1 → 2 → 3 → 4 → Security → 5 → 6 → 7
+
+**Merge vs Phase Execution:**
+- PRs can merge independently (no strict phase ordering for merges)
+- **EXCEPTION:** Security hardening (#28) must merge before any new services are exposed
+- After security merge, deploy with: `nh os switch --flake .#lazyworkhorse`
 
 | Phase | Milestone | Plans Complete | Status | Completed |
 |-------|-----------|----------------|--------|-----------|
diff --git a/assets/ai-optimizer/CRON_EXECUTION_PROMPT.md b/assets/ai-optimizer/CRON_EXECUTION_PROMPT.md
new file mode 100644
index 0000000..20a6600
--- /dev/null
+++ b/assets/ai-optimizer/CRON_EXECUTION_PROMPT.md
@@ -0,0 +1,203 @@
+# AI Model Optimization Cron Job - EXECUTION PROMPT
+
+**When this cron runs, follow these instructions exactly:**
+
+---
+
+## Your Role
+
+You are an AI model optimization agent. Your task is to find the best ollama/llama.cpp configuration for maximum context size and hardware utilization.
+
+**Hardware:**
+- 2× AMD MI50 GPUs (32GB VRAM each, 64GB total)
+- 128GB system RAM
+- ROCm: HSA_OVERRIDE_GFX_VERSION=9.0.6, HIP_VISIBLE_DEVICES=0,1
+
+---
+
+## File Locations
+
+```
+STATE: /opt/data/infra/assets/ai-optimizer/state.json
+RESULTS: /opt/data/infra/assets/ai-optimizer/results.csv
+INFRA_REPO: /opt/data/infra
+```
+
+---
+
+## Model Queues
+
+### GPU Track (Coding - prioritize speed + context on GPU)
+1. `devstral-small-2:24b`
+2. `qwen2.5-coder:32b`
+3. `codellama:34b-instruct`
+
+### RAM Track (Knowledge - prioritize max context)
+1. `qwen2.5:72b`
+2. `nemotron-3-nano:30b`
+3. `mixtral:8x7b-instruct`
+
+---
+
+## Context Steps (in order)
+```
+[32768, 65536, 98304, 131072, 163840, 200704, 262144, 327680]
+```
+
+---
+
+## Each Run - Step by Step
+
+### 1. Read State
+```bash
+cd /opt/data/infra
+cat assets/ai-optimizer/state.json
+```
+
+### 2. Determine Next Test
+- Read `track` (gpu or ram)
+- Read `current_model` from queue at `model_index`
+- Read `current_config` for parameters to test
+- Select next context step from `context_steps` based on `phase`
+
+### 3. Pull Model (if needed)
+```bash
+docker exec ollama ollama list | grep -q "<model>" || docker exec ollama ollama pull <model>
+```
+
+### 4. Create Test Modelfile
+```bash
+docker exec ollama bash -c "cat <<EOF > /root/.ollama/test_${model}.modelfile
+FROM ${model}
+PARAMETER num_ctx ${current_config.num_ctx}
+PARAMETER num_gpu ${current_config.num_gpu}
+PARAMETER flash_attn ${current_config.flash_attn}
+PARAMETER num_predict 4096
+PARAMETER num_keep 1024
+PARAMETER repeat_penalty 1.1
+EOF"
+
+docker exec ollama ollama create test-model -f /root/.ollama/test_${model}.modelfile
+```
+
+### 5. Run Benchmark
+```bash
+# Warm up
+docker exec ollama ollama run test-model "Hello" > /dev/null
+
+# Coding prompt
+START=$(date +%s%N)
+docker exec ollama ollama run test-model "Write a Python async context manager that retries a function with exponential backoff, max 5 retries, and logs each attempt using structlog. Include type hints."
+END=$(date +%s%N)
+
+# Calculate tokens/sec from output
+```
+
+### 6. Measure VRAM (if possible)
+```bash
+# Try host first
+rocm-smi --showmeminfo vram 2>/dev/null || \
+# Try via docker
+docker exec --privileged ollama rocm-smi --showmeminfo vram 2>/dev/null || \
+# Fallback
+echo "VRAM measurement unavailable"
+```
+
+### 7. Record Results
+- Parse tokens/sec from ollama output
+- Record VRAM/RAM usage
+- Determine if this is best config so far for this model
+- Update `best_configs` if tokens/sec improved or context increased
+
+### 8. Update State
+```python
+# Logic:
+if test_successful:
+    if context_step < max_reached:
+        phase = "context_scaling"
+        current_config.num_ctx = next_context_step
+    else:
+        # Move to next model
+        model_index += 1
+        phase = "context_scaling"
+        current_config.num_ctx = context_steps[0]
+else:
+    # OOM or error - record last good as best
+    best_configs[track][current_model] = last_good_config
+    model_index += 1
+    phase = "context_scaling"
+```
+
+### 9. Commit to Repo
+```bash
+cd /opt/data/infra
+git add assets/ai-optimizer/
+git commit -m "ai-optimizer: tested ${model} at ${num_ctx} ctx - ${status}"
+git push origin master
+```
+
+### 10. Matrix Notification (if available)
+```python
+import os
+if os.getenv("MATRIX_HOME_SERVER") and os.getenv("MATRIX_ACCESS_TOKEN"):
+    # Send notification to Matrix room
+    # Room ID from env or config
+    pass
+# Else: silent
+```
+
+---
+
+## Stop Conditions
+
+1. All models in both queues have `best_configs` recorded
+2. Manual intervention needed (error in state.json `error` field)
+3. No progress for 3 consecutive runs (stuck)
+
+---
+
+## Error Handling
+
+If any step fails:
+1. Log error to state.json: `"error": {"message": "...", "timestamp": "..."}`
+2. Do NOT increment model_index (retry next run)
+3. Commit state with error field
+4. Exit gracefully
+
+---
+
+## Important Notes
+
+- **No num_parallel**: Do not use this parameter
+- **Two tracks**: Complete GPU track first, then RAM track
+- **Backend**: Start with ollama, llama.cpp testing is optional (requires uncommenting in compose.yml)
+- **Host access**: Some commands need host - use docker exec or SSH if available
+- **Ask before deploy**: If config changes needed in NixOS modules, show diff and wait for user confirmation before `nh os switch`
+
+---
+
+## Example State Transitions
+
+**Start:**
+```json
+{"track": "gpu", "model_index": 0, "current_model": "devstral-small-2:24b", "current_config": {"num_ctx": 32768, ...}}
+```
+
+**After successful test at 32k:**
+```json
+{"track": "gpu", "model_index": 0, "current_model": "devstral-small-2:24b", "current_config": {"num_ctx": 65536, ...}}
+```
+
+**After OOM at 131k:**
+```json
+{
+  "track": "gpu",
+  "model_index": 1,
+  "current_model": "qwen2.5-coder:32b",
+  "best_configs": {
+    "gpu": {
+      "devstral-small-2:24b": {"num_ctx": 98304, "num_gpu": 99, "tokens_per_sec": 11.2}
+    }
+  }
+}
+```
diff --git a/assets/ai-optimizer/CRON_JOB_DRAFT.md b/assets/ai-optimizer/CRON_JOB_DRAFT.md
new file mode 100644
index 0000000..3ff0781
--- /dev/null
+++ b/assets/ai-optimizer/CRON_JOB_DRAFT.md
@@ -0,0 +1,283 @@
+# AI Model Optimization Cron Job
+
+**Goal:** Find optimal configurations for maximum context size with full hardware utilization.
+
+**Hardware:**
+- 2× AMD MI50 GPUs (32GB VRAM each, 64GB total)
+- 128GB system RAM
+- ROCm: HSA_OVERRIDE_GFX_VERSION=9.0.6, HIP_VISIBLE_DEVICES=0,1
+
+---
+
+## Model Queue
+
+### GPU-Optimized (Coding - prioritize speed + context on GPU)
+1. `devstral-small-2:24b` - Best coding model
+2. `qwen2.5-coder:32b` - Strong coder, fits on GPU+offload
+3. `codellama:34b-instruct` - Legacy but solid
+
+### RAM-Optimized (Knowledge - prioritize max context, accept slower)
+1. `qwen2.5:72b` - Best knowledge, needs heavy offload
+2. `nemotron-3-nano:30b` - Good general knowledge
+3. `mixtral:8x7b-instruct` - MoE, efficient for knowledge
+
+---
+
+## Optimization Strategy
+
+**Two separate tracks:**
+
+### Track A: GPU-Focused (Coding)
+```
+Baseline: num_ctx=32768, num_gpu=99, flash_attn=true
+Steps:
+1. Increase context: 32k → 65k → 98k → 131k → 163k
+2. At each step, verify VRAM usage < 60GB (leave headroom)
+3. If OOM: reduce num_gpu until stable, record best
+4. Measure tokens/sec - if < 5 tok/s, consider context too high
+```
+
+### Track B: RAM-Focused (Knowledge)
+```
+Baseline: num_ctx=65536, num_gpu=50, flash_attn=true
+Steps:
+1. Increase context: 65k → 131k → 200k → 262k → 327k
+2. Allow heavy RAM offload (system RAM up to 100GB)
+3. If OOM: reduce context or num_gpu
+4. Speed less critical - focus on max stable context
+```
+
+---
+
+## Backend-Specific Configs
+
+### Ollama (Modelfile parameters)
+```
+PARAMETER num_ctx <value>
+PARAMETER num_gpu <layers>
+PARAMETER flash_attn true/false
+PARAMETER num_predict 4096
+PARAMETER num_keep 1024
+PARAMETER repeat_penalty 1.1
+```
+
+### Llama.cpp (CLI flags)
+```
+--ctx-size <value>
+--n-gpu-layers <layers>
+--flash-attn on/off
+--n-predict 4096
+--batch-size 4096
+--ubatch-size 512
+--cache-type-k f16
+--cache-type-v f16
+--split-mode layer
+--no-mmap
+```
+
+---
+
+## Host Test Instructions
+
+**The cron runs inside the hermes container. Some tests require host access:**
+
+### 1. VRAM Monitoring (HOST)
+```bash
+# Run on host to check VRAM usage during/after benchmark
+sudo rocm-smi --showmeminfo vram
+
+# Or via docker exec if rocm-smi available in container
+docker exec --privileged ollama rocm-smi --showmeminfo vram
+```
+
+### 2. Running Ollama Benchmarks (CONTAINER)
+```bash
+# Pull model
+docker exec ollama ollama pull <model>
+
+# Create custom modelfile
+docker exec ollama bash -c 'cat <<EOF > /root/.ollama/test.modelfile
+FROM <model>
+PARAMETER num_ctx 65536
+PARAMETER num_gpu 99
+PARAMETER flash_attn true
+EOF'
+
+# Create model from modelfile
+docker exec ollama ollama create test-model -f /root/.ollama/test.modelfile
+
+# Run benchmark (warm model first)
+docker exec ollama ollama run test-model "Write a Python async context manager with exponential backoff"
+
+# Cleanup
+docker exec ollama ollama rm test-model
+```
+
+### 3. Running Llama.cpp Benchmarks (CONTAINER - needs llama.cpp container)
+```bash
+# Uncomment llama_cpp_devstral in compose.yml first
+# Then rebuild: sudo nh os switch --flake .#lazyworkhorse
+
+# Test via HTTP API
+curl http://localhost:8300/v1/completions \
+  -H "Content-Type: application/json" \
+  -d '{
+    "model": "devstral-2-small-llama_cpp",
+    "prompt": "Write a Python function",
+    "max_tokens": 100
+  }'
+```
+
+### 4. Deploying Changes (HOST via ai-worker)
+```bash
+# After optimization, commit results
+cd /home/ai-worker/infra
+git add assets/ai-optimizer/
+git commit -m "ai-optimizer: new best config for <model>"
+git push
+
+# If config changes needed in ollama_init_custom_models.nix:
+# 1. Edit the file
+# 2. nixpkgs-fmt .
+# 3. Show diff to user
+# 4. Wait for confirmation
+# 5. sudo nh os switch --flake .#lazyworkhorse
+```
+
+### 5. Accessing Host from Hermes Container
+```bash
+# SSH to host as ai-worker (key should be mounted)
+ssh -i /path/to/key ai-worker@host.docker.internal
+
+# Or via docker socket if mounted
+# (not recommended for security)
+```
+
+---
+
+## Benchmark Prompts
+
+### Coding (Track A)
+```
+"Write a Python async context manager that retries a function with exponential backoff, max 5 retries, and logs each attempt using structlog. Include type hints and error handling."
+```
+
+### Knowledge (Track B)
+```
+"Explain the complete memory hierarchy in modern GPUs, from registers through L1/L2 caches to VRAM, and how data moves between them during matrix multiplication. Include bandwidth considerations for each level."
+```
+
+### Measurement
+- Tokens per second (generation speed)
+- Time to first token (latency)
+- VRAM usage (via rocm-smi)
+- System RAM usage (via free -h)
+- Context success (did it complete without OOM?)
+
+---
+
+## State File Structure
+
+`/opt/data/infra/assets/ai-optimizer/state.json`
+
+```json
+{
+  "track": "gpu",
+  "current_model": "devstral-small-2:24b",
+  "model_index": 0,
+  "phase": "context_scaling",
+  "backend": "ollama",
+  "current_config": {
+    "num_ctx": 65536,
+    "num_gpu": 99,
+    "flash_attn": true
+  },
+  "best_configs": {
+    "gpu": {
+      "devstral-small-2:24b": {
+        "backend": "ollama",
+        "num_ctx": 131072,
+        "num_gpu": 99,
+        "flash_attn": true,
+        "tokens_per_sec": 12.5,
+        "vram_used_gb": 58.2,
+        "tested_at": "2026-04-28T17:00:00Z"
+      }
+    },
+    "ram": {}
+  },
+  "completed_models": [],
+  "gpu_queue": ["devstral-small-2:24b", "qwen2.5-coder:32b", "codellama:34b-instruct"],
+  "ram_queue": ["qwen2.5:72b", "nemotron-3-nano:30b", "mixtral:8x7b-instruct"]
+}
+```
+
+---
+
+## Results CSV
+
+`/opt/data/infra/assets/ai-optimizer/results.csv`
+
+```csv
+timestamp,track,model,backend,phase,num_ctx,num_gpu,flash_attn,tokens_per_sec,vram_gb,ram_gb,status,is_best
+2026-04-28T17:00:00Z,gpu,devstral-small-2:24b,ollama,context_scaling,65536,99,true,15.2,52.1,18.4,success,false
+```
+
+---
+
+## Cron Job Flow
+
+```
+1. Read state.json
+2. If both queues empty → STOP (all models tested)
+3. Select next model from current track queue
+4. Pull model if needed (docker exec ollama ollama pull)
+5. Create Modelfile / llama.cpp config with current test params
+6. Run benchmark (both prompts)
+7. Measure: tokens/sec, VRAM (rocm-smi), RAM (free -h)
+8. If successful:
+   - Increase context (next step)
+   - Update current_config in state
+9. If OOM/error:
+   - Record last good config as best_configs[track][model]
+   - Move to next model in queue
+10. Update state.json
+11. Append to results.csv
+12. Git commit + push to /opt/data/infra
+13. Send Matrix notification if available, else silent
+```
+
+---
+
+## Matrix Notification (Optional)
+
+```python
+# If matrix credentials available in environment
+if os.getenv("MATRIX_HOME_SERVER") and os.getenv("MATRIX_ACCESS_TOKEN"):
+    # Send completion notification
+    # Room: !ai-optimizer:lazyworkhorse.net (or similar)
+    pass
+# Else: silent, just commit
+```
+
+---
+
+## Files to Create
+
+```
+/opt/data/infra/assets/ai-optimizer/
+├── state.json           # Current progress
+├── results.csv          # All test results
+├── best_configs.json    # Final best configs (human-readable)
+└── CRON_JOB_DRAFT.md    # This file
+```
+
+---
+
+## Notes
+
+- **No num_parallel**: Removed to avoid limiting other settings
+- **Two tracks**: GPU (coding/speed) vs RAM (knowledge/context)
+- **Both backends**: Test ollama first, then llama.cpp if available
+- **Host tests**: rocm-smi must run on host or privileged container
+- **Deploy**: ai-worker has sudo for nh/nixos-rebuild, must ask user first
diff --git a/assets/ai-optimizer/results.csv b/assets/ai-optimizer/results.csv
new file mode 100644
index 0000000..7e25194
--- /dev/null
+++ b/assets/ai-optimizer/results.csv
@@ -0,0 +1 @@
+timestamp,track,model,backend,phase,num_ctx,num_gpu,flash_attn,tokens_per_sec,vram_gb,ram_gb,status,is_best
diff --git a/assets/ai-optimizer/state.json b/assets/ai-optimizer/state.json
new file mode 100644
index 0000000..fff69f9
--- /dev/null
+++ b/assets/ai-optimizer/state.json
@@ -0,0 +1,21 @@
+{
+  "track": "gpu",
+  "current_model": "devstral-small-2:24b",
+  "model_index": 0,
+  "phase": "context_scaling",
+  "backend": "ollama",
+  "current_config": {
+    "num_ctx": 32768,
+    "num_gpu": 99,
+    "flash_attn": true
+  },
+  "best_configs": {
+    "gpu": {},
+    "ram": {}
+  },
+  "completed_models": [],
+  "gpu_queue": ["devstral-small-2:24b", "qwen2.5-coder:32b", "codellama:34b-instruct"],
+  "ram_queue": ["qwen2.5:72b", "nemotron-3-nano:30b", "mixtral:8x7b-instruct"],
+  "context_steps": [32768, 65536, 98304, 131072, 163840, 200704, 262144, 327680],
+  "last_updated": "2026-04-28T17:00:00Z"
+}
diff --git a/assets/compose b/assets/compose
index fb0f2cb..a79fe9d 160000
--- a/assets/compose
+++ b/assets/compose
@@ -1 +1 @@
-Subproject commit fb0f2cbe844b25ca413ded99debc77985bea6281
+Subproject commit a79fe9dffacebae6d4ee17502885e9cdfa852073
diff --git a/docker/hermes/Dockerfile.full b/docker/hermes/Dockerfile.full
new file mode 100644
index 0000000..1edd524
--- /dev/null
+++ b/docker/hermes/Dockerfile.full
@@ -0,0 +1,71 @@
+FROM ghcr.io/astral-sh/uv:0.11.6-python3.13-trixie@sha256:b3c543b6c4f23a5f2df22866bd7857e5d304b67a564f4feab6ac22044dde719b AS uv_source
+FROM tianon/gosu:1.19-trixie@sha256:3b176695959c71e123eb390d427efc665eeb561b1540e82679c15e992006b8b9 AS gosu_source
+FROM debian:13.4
+
+# Disable Python stdout buffering to ensure logs are printed immediately
+ENV PYTHONUNBUFFERED=1
+
+# Store Playwright browsers outside the volume mount so the build-time
+# install survives the /opt/data volume overlay at runtime.
+ENV PLAYWRIGHT_BROWSERS_PATH=/opt/hermes/.playwright
+
+# Install system dependencies in one layer, clear APT cache
+# tini reaps orphaned zombie processes (MCP stdio subprocesses, git, bun, etc.)
+# that would otherwise accumulate when hermes runs as PID 1. See #15012.
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+        build-essential nodejs npm python3 ripgrep ffmpeg gcc python3-dev libffi-dev procps git openssh-client docker-cli tini \
+        curl poppler-utils imagemagick \
+        chromium xvfb fonts-noto-color-emoji fonts-unifont fonts-liberation fonts-ipafont-gothic fonts-wqy-zenhei fonts-tlwg-loma-otf fonts-freefont-ttf \
+        libasound2t64 libatk-bridge2.0-0t64 libatk1.0-0t64 libatspi2.0-0t64 libcairo2 libcups2t64 libdbus-1-3 libdrm2 libgbm1 libglib2.0-0t64 libnspr4 libnss3 libpango-1.0-0 libx11-6 libxcb1 libxcomposite1 libxdamage1 libxext6 libxfixes3 libxkbcommon0 libxrandr2 \
+        texlive-latex-base texlive-latex-extra texlive-fonts-recommended texlive-xetex texlive-science \
+        qemu-user-static binfmt-support qemu-user-binfmt \
+        emacs-nox \
+        libportaudio2 && \
+    rm -rf /var/lib/apt/lists/*
+
+# Non-root user for runtime; UID can be overridden via HERMES_UID at runtime
+RUN useradd -u 10000 -m -d /opt/data hermes
+
+COPY --chmod=0755 --from=gosu_source /gosu /usr/local/bin/
+COPY --chmod=0755 --from=uv_source /usr/local/bin/uv /usr/local/bin/uvx /usr/local/bin/
+
+WORKDIR /opt/hermes
+
+# ---------- Layer-cached dependency install ----------
+# Copy only package manifests first so npm install + Playwright are cached
+# unless the lockfiles themselves change.
+COPY package.json package-lock.json ./
+COPY web/package.json web/package-lock.json web/
+
+RUN npm install --prefer-offline --no-audit && \
+    npx playwright install --with-deps chromium --only-shell && \
+    (cd web && npm install --prefer-offline --no-audit) && \
+    npm cache clean --force
+
+# ---------- Source code ----------
+# .dockerignore excludes node_modules, so the installs above survive.
+COPY --chown=hermes:hermes . .
+
+# Build web dashboard (Vite outputs to hermes_cli/web_dist/)
+RUN cd web && npm run build
+
+# ---------- Permissions ----------
+# Make install dir world-readable so any HERMES_UID can read it at runtime.
+# The venv needs to be traversable too.
+USER root
+RUN chmod -R a+rX /opt/hermes
+# Start as root so the entrypoint can usermod/groupmod + gosu.
+# If HERMES_UID is unset, the entrypoint drops to the default hermes user (10000).
+
+# ---------- Python virtualenv ----------
+RUN uv venv && \
+    uv pip install --no-cache-dir -e ".[all]" && \
+    uv pip install --no-cache-dir sounddevice numpy faster-whisper
+
+# ---------- Runtime ----------
+ENV HERMES_WEB_DIST=/opt/hermes/hermes_cli/web_dist
+ENV HERMES_HOME=/opt/data
+ENV PATH="/opt/data/.local/bin:${PATH}"
+VOLUME [ "/opt/data" ]
+ENTRYPOINT [ "/usr/bin/tini", "-g", "--", "/opt/hermes/docker/entrypoint.sh" ]
diff --git a/hosts/lazyworkhorse/configuration.nix b/hosts/lazyworkhorse/configuration.nix
index 1593b0f..1904449 100644
--- a/hosts/lazyworkhorse/configuration.nix
+++ b/hosts/lazyworkhorse/configuration.nix
@@ -158,7 +158,7 @@
     settings = {
       PasswordAuthentication = false;
       KbdInteractiveAuthentication = false;
-      PermitRootLogin = "prohibit-password"; 
+      # Additional hardening settings below in SERVER HARDENING section
     };
     hostKeys = [
       {
@@ -308,6 +308,189 @@
   # Or disable the firewall altogether.
   # networking.firewall.enable = false;
 
+  # =============================================================================
+  # SERVER HARDENING - Firewall, Fail2ban, SSH, Kernel
+  # =============================================================================
+  
+  # Firewall - default deny, explicit allow
+  networking.firewall = {
+    enable = true;
+    allowPing = true;
+    defaultAllow = false;
+    
+    # Only essential ports exposed to internet
+    allowedTCPPorts = [
+      2424  # SSH (non-standard port)
+      2222  # Gitea (version control)
+      80    # HTTP (Traefik redirect)
+      443   # HTTPS (Traefik)
+      # 8000  # Portainer - REVIEW: internal only?
+      # 4242  # Coms - REVIEW: internal only?
+      # 5000  # TAK API - REVIEW: internal only?
+      # 8087  # TAK Connect - REVIEW: internal only?
+      # 8089  # TAK Management - REVIEW: internal only?
+    ];
+    
+    allowedUDPPorts = [
+      # Add UDP ports if required
+    ];
+    
+    # Rate limiting and attack prevention
+    extraCommands = ''
+      # Rate limit SSH connections (max 4 new connections per 60 seconds)
+      iptables -A INPUT -p tcp --dport 2424 -m state --state NEW -m recent --set
+      iptables -A INPUT -p tcp --dport 2424 -m state --state NEW -m recent --update --seconds 60 --hitcount 4 -j DROP
+      
+      # Rate limit HTTP/HTTPS (protects Traefik)
+      iptables -A INPUT -p tcp --dport 80 -m state --state NEW -m limit --limit 25/minute --limit-burst 100 -j ACCEPT
+      iptables -A INPUT -p tcp --dport 443 -m state --state NEW -m limit --limit 25/minute --limit-burst 100 -j ACCEPT
+      
+      # Drop invalid packets
+      iptables -A INPUT -m state --state INVALID -j DROP
+      
+      # Log dropped packets (rate limited)
+      iptables -A INPUT -m limit --limit 5/min -j LOG --log-prefix "IPTables-Dropped: " --log-level 4
+    '';
+  };
+
+  # Fail2ban - automatic IP banning
+  services.fail2ban = {
+    enable = true;
+    maxRetry = 3;
+    findtime = 600;
+    bantime = 3600;
+    banaction = "iptables-multiport";
+    
+    # Ban repeat offenders for 1 week
+    recidive = {
+      enabled = true;
+      filter = "recidive";
+      logpath = "/var/log/fail2ban.log";
+      bantime = 604800;
+      findtime = 86400;
+      maxretry = 3;
+    };
+    
+    jails = {
+      # SSH brute force protection (uses systemd journal backend)
+      sshd = {
+        enabled = true;
+        filter = "sshd";
+        port = "2424";
+        maxretry = 3;
+        bantime = 3600;
+      };
+      
+      # HTTP authentication failures (Traefik)
+      http-auth = {
+        enabled = true;
+        filter = "traefik-auth";
+        port = "80,443";
+        logpath = "/var/log/traefik/access.log";
+        maxretry = 5;
+        bantime = 3600;
+      };
+      
+      # HTTP scanning/attacks (Traefik)
+      http-botsearch = {
+        enabled = true;
+        filter = "traefik-botsearch";
+        port = "80,443";
+        logpath = [ "/var/log/traefik/access.log" ];
+        maxretry = 2;
+        bantime = 7200;
+      };
+    };
+  };
+  
+  # Custom fail2ban filters for Traefik
+  environment.etc."fail2ban/filter.d/traefik-auth.conf".text = ''
+    [Definition]
+    failregex = ^<HOST> -.*"(GET|POST|HEAD|PUT|DELETE).*" (401|403) \d+.*$
+    ignoreregex =
+  '';
+  
+  environment.etc."fail2ban/filter.d/traefik-botsearch.conf".text = ''
+    [Definition]
+    failregex = ^<HOST> -.*"(GET|POST|HEAD|PUT|DELETE).*" 404 \d+.*$
+                ^<HOST> -.*"(GET|POST|HEAD|PUT|DELETE).*/(\.|wp-|php|admin|login|xmlrpc|\.env|\.git|\.aws|\.azure).*" \d+.*$
+    ignoreregex =
+  '';
+
+  # SSH hardening
+  services.openssh.settings = {
+    PermitRootLogin = "no";
+    MaxAuthTries = 3;
+    MaxSessions = 5;
+    LoginGraceTime = 30;
+    ClientAliveInterval = 300;
+    ClientAliveCountMax = 2;
+    PermitEmptyPasswords = "no";
+    ChallengeResponseAuthentication = "no";
+    UsePAM = true;
+    LogLevel = "VERBOSE";
+    X11Forwarding = false;
+    AllowTcpForwarding = "no";
+    AllowAgentForwarding = "no";
+    PermitTunnel = "no";
+  };
+
+  # Kernel network hardening
+  boot.kernel.sysctl = {
+    # IP Spoofing protection
+    "net.ipv4.conf.all.rp_filter" = 1;
+    "net.ipv4.conf.default.rp_filter" = 1;
+    
+    # Ignore ICMP broadcasts
+    "net.ipv4.icmp_echo_ignore_broadcasts" = 1;
+    
+    # Disable source routing
+    "net.ipv4.conf.all.accept_source_route" = 0;
+    "net.ipv4.conf.default.accept_source_route" = 0;
+    "net.ipv6.conf.all.accept_source_route" = 0;
+    "net.ipv6.conf.default.accept_source_route" = 0;
+    
+    # Disable redirects
+    "net.ipv4.conf.all.send_redirects" = 0;
+    "net.ipv4.conf.default.send_redirects" = 0;
+    
+    # SYN flood protection
+    "net.ipv4.tcp_syncookies" = 1;
+    "net.ipv4.tcp_max_syn_backlog" = 2048;
+    "net.ipv4.tcp_synack_retries" = 2;
+    "net.ipv4.tcp_syn_retries" = 5;
+    
+    # Log martian packets
+    "net.ipv4.conf.all.log_martians" = 1;
+    "net.ipv4.conf.default.log_martians" = 1;
+    
+    # Ignore redirects
+    "net.ipv4.conf.all.accept_redirects" = 0;
+    "net.ipv4.conf.default.accept_redirects" = 0;
+    "net.ipv4.conf.all.secure_redirects" = 0;
+    "net.ipv4.conf.default.secure_redirects" = 0;
+    "net.ipv6.conf.all.accept_redirects" = 0;
+    "net.ipv6.conf.default.accept_redirects" = 0;
+    
+    # Connection tuning
+    "net.core.somaxconn" = 4096;
+    "net.core.netdev_max_backlog" = 65536;
+    "net.ipv4.tcp_max_orphans" = 65536;
+    "net.ipv4.tcp_fin_timeout" = 15;
+    "net.ipv4.tcp_keepalive_time" = 300;
+    "net.ipv4.tcp_keepalive_probes" = 5;
+    "net.ipv4.tcp_keepalive_intvl" = 15;
+  };
+
+  # Audit logging
+  services.auditd.enable = true;
+  
+  # Fail2ban log directory
+  systemd.tmpfiles.rules = [
+    "d /var/log/fail2ban 0755 root root -"
+    "d /var/log/traefik 0755 root root -"
+  ];
+
   # Copy the NixOS configuration file and link it from the resulting system
   # (/run/current-system/configuration.nix). This is useful in case you
   # accidentally delete configuration.nix.
diff --git a/users/ai-worker.nix b/users/ai-worker.nix
index a8f027c..b818426 100644
--- a/users/ai-worker.nix
+++ b/users/ai-worker.nix
@@ -11,4 +11,71 @@
     ];
   };
   users.groups.ai-worker = {};
+  
+  # Restricted sudo for ai-worker - security checks only
+  security.sudo.extraRules = [
+    {
+      users = [ "ai-worker" ];
+      commands = [
+        # Firewall checks
+        {
+          command = "/run/wrappers/bin/sudo iptables -L -n -v";
+          options = [ "NOPASSWD" ];
+        }
+        {
+          command = "/run/wrappers/bin/sudo iptables -S";
+          options = [ "NOPASSWD" ];
+        }
+        # Fail2ban status
+        {
+          command = "/run/current-system/sw/bin/fail2ban-client status";
+          options = [ "NOPASSWD" ];
+        }
+        {
+          command = "/run/current-system/sw/bin/fail2ban-client status *";
+          options = [ "NOPASSWD" ];
+        }
+        {
+          command = "/run/current-system/sw/bin/fail2ban-client get * banned";
+          options = [ "NOPASSWD" ];
+        }
+        # Log inspection
+        {
+          command = "/run/current-system/sw/bin/journalctl -t kernel -n 100";
+          options = [ "NOPASSWD" ];
+        }
+        {
+          command = "/run/current-system/sw/bin/journalctl -u fail2ban -n 50";
+          options = [ "NOPASSWD" ];
+        }
+        {
+          command = "/run/current-system/sw/bin/journalctl -u firewall -n 50";
+          options = [ "NOPASSWD" ];
+        }
+        # SSH config verification
+        {
+          command = "/run/current-system/sw/bin/sshd -T";
+          options = [ "NOPASSWD" ];
+        }
+        # Docker service checks
+        {
+          command = "/run/current-system/sw/bin/docker ps";
+          options = [ "NOPASSWD" ];
+        }
+        {
+          command = "/run/current-system/sw/bin/docker inspect *";
+          options = [ "NOPASSWD" ];
+        }
+        # Network diagnostics
+        {
+          command = "/run/current-system/sw/bin/ss -tlnp";
+          options = [ "NOPASSWD" ];
+        }
+        {
+          command = "/run/current-system/sw/bin/cat /proc/net/tcp";
+          options = [ "NOPASSWD" ];
+        }
+      ];
+    }
+  ];
 }