ALL Tips to Secure your linux VPS server

Introduction
#

Securing your VPS hosting server is paramount before exposing it to the public. Here’s how you can bolster your server’s defenses.

1. Regularly Update Your System
#

Keeping your Linux system up to date is vital for security. Regularly apply security updates using the following commands:

sudo apt-get update -y
sudo apt-get upgrade -y

2. Add a New User with Sudo Privileges
#

Improving security involves creating a new user with administrative capabilities:

Create a New User: Add a new user to your system, replacing newusername with your preferred username.
```
sudo adduser newusername
```
Grant Sudo Privileges: Enable the new user to use the sudo command by adding them to the sudo group.
```
sudo usermod -aG sudo newusername
```
Test Sudo Access: Verify that the new user can use sudo by switching to their account and running a test command.
```
su - newusername
sudo ls -la /root
```
Exit User Account: Once the test is complete, exit the new user’s account.
```
exit
```
Access sudoers File: To edit the sudoers file, use:
- If you’re currently logged in as root:
```
visudo
```
- If you’re logged in as a non-root user with sudo privileges:
```
sudo visudo
```
Edit with Ease: The visudo command typically uses the nano text editor, making it user-friendly. Navigate with arrow keys and locate the line resembling:
```
root    ALL=(ALL:ALL) ALL
```
Add User to sudoers: Below the mentioned line, add the highlighted line (replace newuser with the actual username):
```
root    ALL=(ALL:ALL) ALL
newusername ALL=(ALL:ALL) ALL
```
Save and Exit: Save your changes and exit the editor.

These steps grant specific users sudo privileges, allowing them to execute administrative commands while maintaining a secure server environment.

3. Avoid Password Login
#

Enhance security by disabling password-based logins and exclusively utilizing SSH key authentication.

PasswordAuthentication no

4. Use SSH Key Authentication
#

For authentication, use SSH key pairs. Generate a key pair on your local machine and add the public key to the server’s ~/.ssh/authorized_keys file.

ssh-keygen -t rsa
ssh-copy-id newusername@your_server_ip

5. Install a Firewall & Change SSH Port Number
#

Fortify your server’s security by configuring a firewall and modifying the SSH port number:

Install UFW (Uncomplicated Firewall): Begin by installing the Uncomplicated Firewall, which simplifies managing firewall rules.
```
sudo apt-get install ufw
```
Enable UFW: Activate UFW and ensure it starts automatically at boot.
```
sudo ufw enable
```
Allow SSH Traffic on Custom Port: Permit SSH traffic on the custom port you’ve chosen (replace your_custom_port_number with your desired port).
```
sudo ufw allow your_custom_port_number/tcp
```
Change SSH Port Number: Modify the default SSH port (22) to your chosen custom port. This adds an extra layer of security by moving SSH away from the default port.
```
sudo nano /etc/ssh/sshd_config
# Change 'Port 22' to 'Port your_custom_port_number'
# Save the file and exit the text editor
sudo service sshd restart
```

By completing these steps, you establish a firewall, modify the SSH port, and enhance your server’s security, reducing potential threats.

6. Restrict User Logins
#

Allow only specific users to log in via SSH. Edit the SSH configuration file (/etc/ssh/sshd_config).

AllowUsers newusername

7. Disable Root Login
#

Prevent direct root login via SSH. Edit the SSH configuration file.

PermitRootLogin no

8. Restrict Ping Responses
#

Disable ICMP ping responses to thwart potential reconnaissance attacks:

Open the UFW (Uncomplicated Firewall) configuration file:
```
sudo nano /etc/ufw/before.rules
```
Add this line at the file’s end to block ICMP echo request (ping) packets:
```
-A ufw-before-input -p icmp --icmp-type echo-request -j DROP
```
Save the file and exit the text editor.
Reload the UFW rules to apply the changes:
```
sudo ufw reload
```
Reboot your server to ensure the changes take effect:
```
sudo reboot
```

By implementing these measures, you effectively prevent your server from responding to ICMP ping requests, reducing its exposure to potential reconnaissance attempts.

Conclusion
#

Security is an ongoing process. Regularly review and update your security measures to adapt to emerging threats. By following these steps and using the provided command lines, you significantly enhance your VPS hosting server’s security, ensuring a safer environment for your applications and data.