Update tech_docs/its_the_new_style_design.md

tech_docs/its_the_new_style_design.md

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+Here is a concise, step-by-step crash course that will get you productive with **dnsmasq** on a minimal Debian 12 server that you only reach via SSH.  
+Everything is copy-paste friendly; run the commands in the order shown.
+
+--------------------------------------------------------------------
+1. Prepare the OS (run once)
+--------------------------------------------------------------------
+```bash
+sudo apt update && sudo apt upgrade -y
+# Prevent Debian’s own stub resolver from clashing
+sudo systemctl disable --now systemd-resolved
+sudo unlink /etc/resolv.conf
+# Give the machine a working upstream DNS while we build our own
+echo -e "nameserver 1.1.1.1\nnameserver 8.8.8.8" | sudo tee /etc/resolv.conf
+```
+
+--------------------------------------------------------------------
+2. Install dnsmasq
+--------------------------------------------------------------------
+```bash
+sudo apt install dnsmasq -y
+sudo systemctl enable --now dnsmasq
+```
+
+--------------------------------------------------------------------
+3. Create a lean config file
+--------------------------------------------------------------------
+Back up the default and drop a new file in `/etc/dnsmasq.d/` so upgrades never overwrite your edits.
+
+```bash
+sudo cp /etc/dnsmasq.conf /etc/dnsmasq.conf.bak
+sudo nano /etc/dnsmasq.d/01-lab.conf
+```
+
+Paste the following (edit interface/addresses to match your box):
+
+```
+# Listen only on the LAN NIC and loopback
+interface=eth0                 # or enp0s3, ens10, etc.
+listen-address=127.0.0.1,192.168.5.20   # <— your server IP
+
+# DNS part
+cache-size=1000
+no-resolv
+server=1.1.1.1
+server=8.8.8.8
+expand-hosts
+domain=lab.local
+
+# DHCP part (remove if you only want DNS)
+dhcp-range=192.168.5.50,192.168.5.150,24h
+dhcp-option=3,192.168.5.1     # default gateway
+dhcp-option=6,192.168.5.20    # dns server (this box)
+dhcp-authoritative
+```
+
+Save, exit, then test and reload:
+
+```bash
+sudo dnsmasq --test && sudo systemctl restart dnsmasq
+```
+
+--------------------------------------------------------------------
+4. Add any static hostnames you like
+--------------------------------------------------------------------
+```bash
+sudo nano /etc/hosts
+# Example lines
+192.168.5.10  git.lab.local   git
+192.168.5.11  db.lab.local    db
+```
+After saving, the names are immediately resolvable by dnsmasq (no restart needed).
+
+--------------------------------------------------------------------
+5. Make the server use its own dnsmasq
+--------------------------------------------------------------------
+```bash
+sudo nano /etc/resolv.conf
+# First nameserver must be localhost
+nameserver 127.0.0.1
+```
+
+--------------------------------------------------------------------
+6. Verify from the server itself
+--------------------------------------------------------------------
+```bash
+dig +short git.lab.local        # → 192.168.5.10
+dig +short debian.org           # → some IP (proves upstream works)
+```
+
+--------------------------------------------------------------------
+7. Open the firewall (if you use ufw)
+--------------------------------------------------------------------
+```bash
+sudo ufw allow from 192.168.5.0/24 to any port 53
+sudo ufw allow from 192.168.5.0/24 to any port 67  # only if you enabled DHCP
+```
+
+--------------------------------------------------------------------
+8. Point a client at it (quick test from your laptop)
+--------------------------------------------------------------------
+Temporarily override your laptop’s DNS:
+
+```bash
+# Linux / macOS
+sudo resolvectl dns eth0 192.168.5.20
+dig git.lab.local
+```
+
+--------------------------------------------------------------------
+9. Watch the logs
+--------------------------------------------------------------------
+```bash
+sudo journalctl -fu dnsmasq
+```
+
+That’s it—you now have a local DNS cache, custom domain names, and (optionally) a DHCP server running on your minimal Debian 12 box.  
+For deeper tweaks, the heavily-commented `/etc/dnsmasq.conf` and any files under `/etc/dnsmasq.d/` are your playground.
+
+---
+
 Below is a single, opinionated, **Debian-only** decade scheme that you can clone into `/etc/linux-decades/` (or keep in Git and symlink).  
 Everything is pure Debian tooling—`apt`, `debconf`, `systemd`, `sysctl.d`, `sudoers.d`, `nftables`, etc.—no network-centric artifacts.