Network Interface Configuration - static IP

In Debian OS (the appliance is based o it) , network interface settings are primarily managed within the /etc/network/interfaces file and the /etc/network/interfaces.d/ directory, which can contain additional configuration files. Here, you define your network interfaces and specify how they should obtain an IP address, among other settings.

Execute everything under root user or under sudo

• DHCP:
  

  example configures the eth0 interface to use DHCP to obtain an IP address automatically (default in Virtual Appliance).

  vi /etc/network/interfaces
  
  # The primary network interface
  allow-hotplug eth0
  iface eth0 inet dhcp

• Static IP:
  

  For a static IP configuration, you would specify the address, netmask, gateway, and possibly DNS nameservers.

  vi /etc/network/interfaces
  
  # The primary network interface
  allow-hotplug eth0
  iface eth0 inet static
      address 192.168.1.100
      netmask 255.255.255.0
      gateway 192.168.1.1
      dns-nameservers 8.8.8.8 8.8.4.4

Applying Network Configuration Changes

After editing your network configuration files, apply the changes using the ifdown and ifup commands. These commands deactivate and reactivate your network interface, respectively.

ifdown eth0 && ifup eth0

For the new network settings to take effect, you may also restart the networking service entirely.

systemctl restart networking

More info: man interfaces or How To set static IP on a Debian Linux.