Static IP configuration can be found in file /etc/network/interfaces. This applies to Debian or any derivatives such as Ubuntu.

Edit the file /etc/network/interfaces using sudo command

sudo pico /etc/network/interfaces

Change the file content to be similar like below. Please ensure to look closely on iface eth0 section. You can change the IP address based on your preferred address.

[code language=”bash”]# The loopback interface
auto lo
iface lo inet loopback

# Configuration for eth0 and aliases

# This line ensures that the interface will be brought up during boot.
auto eth0

# eth0 – This is the main IP address that will be used for most outbound connections.
# The address, netmask and gateway are all necessary.
iface eth0 inet static
address 192.168.1.10
netmask 255.255.255.0
gateway 192.168.1.1[/code]

In case if you want to configure static IP in any virtual machine such as VirtualBox, you may need to adjust dns-nameservers manually
[code language=”bash”]iface eth0 inet static
address 192.168.1.10
netmask 255.255.255.0
dns-nameservers 192.168.1.1
gateway 192.168.1.1
[/code]

It is better to disable root user login since allowing root user login is a major security concern in Linux system. You can use root login after logging in as another user.

1. Edit sshd_config file.

sudo pico /etc/ssh/sshd_config

2. Search PermitRootLogin directive in that file and change PermitRootLogin to no. Example:

# Authentication:
LoginGraceTime 120
PermitRootLogin no
StrictModes yes

You should install all available security updates in order to protect against unauthorised access to your Linux/Ubuntu box. The commands can be found in the following.

sudo apt-get update
sudo apt-get upgrade --show-upgraded

Please ensure to enter your root password since you are using sudo command that gains super access to your Linux system.