• ip a to see interfaces + ip addresses.
• ifw disable disables the ubuntu firewall.

To change the network configuration in new Ubuntu versions.

There is an .yml software in /etc/netplan. To apply changes use the next command:

netplan apply

network:
  version: 2
  renderer: networkd
  ethernets:
    enp3s0:
      addresses:
        - 10.10.10.2/24
      gateway4: 10.10.10.1
      nameservers:
          search: [mydomain, otherdomain]
          addresses: [10.10.10.1, 1.1.1.1]

network:
  version: 2
  renderer: networkd
  ethernets:
    enp3s0:
      dhcp4: true

network:
  version: 2
  renderer: NetworkManager