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tech_docs/linux/debian_networking.md

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+Certainly! Here's a more detailed guide on how to manage network configurations on a Debian 12 server using different methods, with additional context and instructions tailored to your preference for using VIM as a text editor.
+
+### Network Configuration on Debian 12
+
+Debian 12 can manage network configurations through traditional Debian methods like the `/etc/network/interfaces` file, or modern methods such as `systemd-networkd` and NetworkManager. Below is a comprehensive guide on how to adjust the default route using these methods, and how to use VIM for editing configuration files.
+
+### 1. Using `/etc/network/interfaces`
+
+For servers not using NetworkManager or `systemd-networkd`, the network settings are traditionally managed via the `/etc/network/interfaces` file.
+
+**Steps to modify the default route:**
+
+- **Open the configuration file with VIM**:
+  ```bash
+  sudo vim /etc/network/interfaces
+  ```
+
+- **Configure your network interface**: Here's an example of what your configuration might look like if you're setting a static IP and want to define which gateway the server should use:
+
+  ```plaintext
+  auto eth0
+  iface eth0 inet static
+      address 192.168.1.100
+      netmask 255.255.255.0
+      gateway 192.168.1.1
+  ```
+
+  Make sure to replace `eth0` with the correct interface name, and update the `address`, `netmask`, and `gateway` with appropriate values for your network. Only set the `gateway` for the interface that should be the default route.
+
+- **Restart networking to apply changes**:
+  ```bash
+  sudo systemctl restart networking
+  ```
+
+### 2. Using `systemd-networkd`
+
+If your server uses `systemd-networkd` for managing network interfaces, you'll configure them via `.network` files located in `/etc/systemd/network/`.
+
+- **Create or edit a network file for your interface**:
+  ```bash
+  sudo vim /etc/systemd/network/10-eth0.network
+  ```
+
+  Here is what the configuration might look like:
+  ```plaintext
+  [Match]
+  Name=eth0
+  
+  [Network]
+  DHCP=no
+  Address=192.168.1.100/24
+  Gateway=192.168.1.1
+  DNS=8.8.8.8
+  ```
+
+  Adjust the interface name and network settings as necessary.
+
+- **Restart `systemd-networkd` to apply changes**:
+  ```bash
+  sudo systemctl restart systemd-networkd
+  ```
+
+### 3. Using NetworkManager
+
+For servers with a graphical interface or for those preferring NetworkManager:
+
+- **Edit connections using NMTUI**, or for command line changes:
+  ```bash
+  nmcli connection modify <connection-name> ipv4.addresses "192.168.1.100/24" ipv4.gateway "192.168.1.1" ipv4.dns "8.8.8.8" ipv4.method manual
+  ```
+  Replace `<connection-name>` with the name of your connection.
+
+- **Apply changes**:
+  ```bash
+  nmcli connection up <connection-name>
+  ```
+
+### Making Temporary Changes
+
+For temporary routing adjustments:
+
+- **Delete the existing default route**:
+  ```bash
+  sudo ip route del default
+  ```
+- **Add a new default route**:
+  ```bash
+  sudo ip route add default via 192.168.1.1 dev eth0
+  ```
+
+These commands will modify the routing table until the next reboot or restart of the network service.
+
+This comprehensive guide should help you manage your Debian server's network settings effectively. Whether you're making temporary changes or configuring settings for long-term use, these steps will ensure your network is set up according to your needs.