Update tech_docs/linux/next_level_debian.md

tech_docs/linux/next_level_debian.md

@@ -1,6 +1,131 @@
-Here's a **`next_level_debian.md`** document that captures all the hardcore optimizations we've discussed, organized for clarity and reuse:
+Your document is already well-organized, but here are some suggestions to make it even better:
 
+### Structural Improvements:
+1. **Split Into Multiple Files**:
+   - Consider separating the "Hardening Guide" and "PCIe Passthrough Guide" into two distinct files
+   - Create a `docs/` directory with:
+     ```
+     docs/
+     ├── hardening/
+     │   ├── services.md
+     │   ├── network.md
+     │   └── kernel.md
+     ├── virtualization/
+     │   ├── pcie-passthrough.md
+     │   └── kvm-optimization.md
+     └── README.md (main index)
+     ```
+
+2. **Enhanced Navigation**:
+   ```markdown
+   ## Quick Links
+   [![Hardening](https://img.shields.io/badge/Go_to-Hardening-blue)](#service-hardening)
+   [![Passthrough](https://img.shields.io/badge/Go_to-PCIe_Passthrough-green)](#pcie-passthrough-guide-for-debian)
+   ```
+
+### Content Improvements:
+1. **Add Risk Indicators**:
+   ```markdown
+   ### :warning: Extreme Measures (Potential Breakage)
+   ```bash
+   sudo apt purge --auto-remove -y snapd lxd  # [!DANGER]
+   ```
+   > **Legend**:  
+   > [!NOTE] - Safe  
+   > [!WARNING] - May affect functionality  
+   > [!DANGER] - High breakage risk  
+   ```
+
+2. **Version Compatibility**:
+   ```markdown
+   ## Compatibility Matrix
+   | Debian Version | Kernel Min | Recommended |
+   |----------------|------------|-------------|
+   | Bookworm (12)  | 6.1.x      | 6.5+        |
+   | Trixie (13)    | 6.6.x      | 6.8+        |
+   ```
+
+### Automation Enhancements:
+1. **Add Verification Scripts**:
+   ```bash
+   #!/bin/bash
+   # verify_hardening.sh
+   echo "=== Service Check ==="
+   systemctl list-units --type=service --state=running --no-pager | head -n 5
+   
+   echo "=== Immutable Files Check ==="
+   lsattr /etc/passwd /etc/shadow | grep "----i"
+   ```
+
+2. **Include Rollback Procedures**:
+   ```markdown
+   ## Rollback Changes
+   ### Revert SSH Hardening
+   ```bash
+   sudo sed -i 's/^PermitRootLogin no/PermitRootLogin prohibit-password/' /etc/ssh/sshd_config
+   ```
+   ```
+
+### Visual Improvements:
+1. **Add ASCII Diagrams**:
+   ```markdown
+   ## Network Flow
+   ```
+   [Internet] -> [nftables] -> (DROP)
+                   └─[tcp dport 2222] -> [SSH]
+   ```
+
+2. **Include Hardware-Specific Notes**:
+   ```markdown
+   ### i7-4790 Specifics
+   ```diff
+   - Avoid assigning all cores to VM
+   + Keep at least 1 physical core for host
+   ```
+   ```
+
+### Documentation Hygiene:
+1. **Add Change Log**:
+   ```markdown
+   ## Revision History
+   | Date       | Version | Changes               |
+   |------------|---------|-----------------------|
+   | 2024-06-01 | 1.1     | Added i350 NIC notes  |
+   ```
+
+2. **Include Contributor Guidelines**:
+   ```markdown
+   ## How to Contribute
+   1. Fork this document
+   2. Test changes on VM first
+   3. Submit PR with verification output
+   ```
+
+### Example Improved Section:
 ```markdown
+## :gear: Kernel Protections [!RECOMMENDED]
+
+### Priority Settings
+```bash
+# /etc/sysctl.d/99-hardening.conf
+#
+# Kernel pointer restrictions (1=hidden, 2=hidden+log)
+kernel.kptr_restrict=2
+
+# Disable unprivileged namespace creation
+kernel.unprivileged_userns_clone=0
+```
+
+> **Performance Impact**: <5% CPU overhead on synthetic benchmarks
+```
+
+Would you like me to:
+1. Generate a complete revised version with these improvements?
+2. Create template files for the suggested directory structure?
+3. Focus on enhancing a specific section (e.g., PCIe passthrough)?
+
+---
+
 # Next-Level Debian Hardening & Minimalism
 
 For power users who want **maximum control, security, and performance** from their Debian system.