CBT Nugget: Linux Server Administration - 12.Identifying Debian and Ubuntu Network Configuration Files

12.Identifying Debian and Ubuntu Network Configuration Files

On Debian and Ubuntu systems, network configuration files are primarily located in the /etc directory. Below are the key files and their purposes:

1. /etc/network/interfaces

• Purpose: This file is used to configure network interfaces.
• Content Example:

  plaintext
  auto lo
  iface lo inet loopback
  
  auto eth0
  iface eth0 inet dhcp
  

2. /etc/hostname

• Purpose: This file contains the system's hostname.
• Content Example:

  plaintext
  myhostname
  

3. /etc/hosts

• Purpose: This file maps IP addresses to hostnames for local name resolution.
• Content Example:

  plaintext
  127.0.0.1   localhost
  127.0.1.1   myhostname
  

4. /etc/resolv.conf

• Purpose: This file configures DNS name servers.
• Content Example:

  plaintext
  nameserver 8.8.8.8
  nameserver 8.8.4.4
  

5. /etc/nsswitch.conf

• Purpose: This file specifies the order of sources used to resolve different types of information (e.g., hostnames).
• Content Example:

  plaintext
  hosts:          files dns
  

6. /etc/network/interfaces.d/

• Purpose: This directory contains additional network interface configuration files. Each file in this directory is included in the primary /etc/network/interfaces file.
• Usage: Separate interface configuration files can be placed here for better organization.

Systemd-based Network Configuration

In newer versions of Debian and Ubuntu, network configuration can also be managed by systemd-networkd or netplan.

netplan

• Configuration Directory: /etc/netplan/
• Configuration Files: YAML files that define network settings.
• Example Configuration File (/etc/netplan/01-netcfg.yaml):

  yaml
  network:
    version: 2
    renderer: networkd
    ethernets:
      eth0:
        dhcp4: true
  

systemd-networkd

• Configuration Directory: /etc/systemd/network/
• Configuration Files: .network files defining network settings.
• Example Configuration File (/etc/systemd/network/10-eth0.network):

  ini
  [Match]
  Name=eth0
  
  [Network]
  DHCP=ipv4
  

Managing Network Services

• Restart Networking Service: After modifying network configuration files, restart the networking service to apply changes.

  bash
  sudo systemctl restart networking
  

• Apply Netplan Configuration: If using netplan, apply the configuration with:

  bash
  sudo netplan apply
  

These files and directories are essential for configuring and managing network settings on Debian and Ubuntu systems.