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the_information_nexus/tech_docs/linux/debian_networking.md
2024-05-01 12:28:44 -06:00

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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:

    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:

    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:

    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:

    sudo vim /etc/systemd/network/10-eth0.network
    

    Here is what the configuration might look like:

    [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:

    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:

    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:

    nmcli connection up <connection-name>
    

Making Temporary Changes

For temporary routing adjustments:

  • Delete the existing default route:
    sudo ip route del default
    
  • Add a new default route:
    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.