20250907

projects/gg/avahi_mdns-reflector/prep/20250714-linux-interface-conf.md

@@ -0,0 +1,102 @@
+
+To configure VLANs with **static IP addresses** on Debian using the native `/etc/network/interfaces` file, follow this setup. This replicates your current configuration using VLANs on `eth0` and assigns static IPs to `eth0.20` and `eth0.30`.
+
+---
+
+### 📁 **/etc/network/interfaces Configuration**
+
+```bash
+# Define VLAN interfaces with static IPs
+auto eth0
+iface eth0 inet static
+    address 10.56.0.243/24
+    gateway 10.56.0.1
+    dns-nameservers 8.8.8.8 8.8.4.4
+
+auto eth0.20
+iface eth0.20 inet static
+    address 10.56.2.103/24
+    gateway 10.56.2.1
+    dns-nameservers 8.8.8.8 8.8.4.4
+    inet6 address 2001:db8::1/64
+    inet6 gateway 2001:db8::1
+    inet6 dns-nameservers 2001:4860:4860::8888 2001:4860:4860::8844
+
+auto eth0.30
+iface eth0.30 inet static
+    address 10.56.3.108/24
+    gateway 10.56.3.1
+    dns-nameservers 8.8.8.8 8.8.4.4
+    inet6 address 2001:db8::2/64
+    inet6 gateway 2001:db8::2
+    inet6 dns-nameservers 2001:4860:4860::8888 2001:4860:4860::8844
+```
+
+---
+
+### 🧰 **Steps to Apply the Configuration**
+
+1. **Install `vconfig`** (required for VLANs):
+   ```bash
+   sudo apt update
+   sudo apt install vconfig
+   ```
+
+2. **Create VLAN interfaces** (if not already created):
+   ```bash
+   sudo vconfig add eth0 20
+   sudo vconfig add eth0 30
+   ```
+
+3. **Update `/etc/network/interfaces`** with the above configuration.
+
+4. **Restart networking**:
+   ```bash
+   sudo systemctl restart networking
+   ```
+
+5. **Verify interfaces**:
+   ```bash
+   ip a
+   ```
+   You should see `eth0.20` and `eth0.30` with static IPs assigned.
+
+---
+
+### 📌 **Key Notes**
+
+1. **VLAN Interface Creation**:
+   - The `vconfig` tool creates the VLAN interfaces (`eth0.20`, `eth0.30`).
+   - Ensure `vconfig` is installed to manage VLANs.
+
+2. **Static IPs**:
+   - Use `address` for IPv4 and `inet6 address` for IPv6.
+   - Set `gateway` and `dns-nameservers` for routing and DNS.
+
+3. **IPv6 Support**:
+   - IPv6 addresses are configured using `inet6 address` and `inet6 gateway`.
+   - Ensure your network supports IPv6 or adjust accordingly.
+
+4. **Parent Interface (`eth0`)**:
+   - `eth0` is configured with a static IP (`10.56.0.243/24`) and a default gateway (`10.56.0.1`).
+
+---
+
+### 🧪 **Validation**
+
+After applying the configuration:
+- Check IP addresses:
+  ```bash
+  ip a
+  ```
+- Test connectivity:
+  ```bash
+  ping -c 4 8.8.8.8
+  ping -c 4 2001:4860:4860::8888
+  ```
+
+---
+
+### 📝 Summary
+
+This `/etc/network/interfaces` configuration sets up VLANs (`eth0.20`, `eth0.30`) with **static IPv4 and IPv6 addresses**, matching your original setup. It avoids manual `ip link` commands and ensures consistent networking behavior.