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

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.

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📁 /etc/network/interfaces Configuration

# 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

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🧰 Steps to Apply the Configuration

1. Install vconfig (required for VLANs):

   sudo apt update
   sudo apt install vconfig
   

2. Create VLAN interfaces (if not already created):

   sudo vconfig add eth0 20
   sudo vconfig add eth0 30
   

3. Update /etc/network/interfaces with the above configuration.

4. Restart networking:

   sudo systemctl restart networking
   

5. Verify interfaces:

   ip a
   

   You should see eth0.20 and eth0.30 with static IPs assigned.

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📌 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).

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🧪 Validation

After applying the configuration:

• Check IP addresses:

  ip a
  

• Test connectivity:

  ping -c 4 8.8.8.8
  ping -c 4 2001:4860:4860::8888
  

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📝 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.