VPS security: how to block access and protect your server

How to protect your VPS server from attacks

If you're a virtual private server user, it's helpful to know the existing VPS security rules and how they work.

1. Authentication with strong passwords and SSH keys.

Let's start by saying that passwords are the most common way to log into a server, but also the most vulnerable. A short or obvious password can be automatically guessed: hundreds of bots around the world try different combinations around the clock, like hackers trying master keys. If you use something like «admin123», they'll easily get in.

That's why it's important to create a long, complex password that's difficult to guess. But an even better way to protect your data is with SSH keys. These are special files that act like a unique digital key: it's virtually impossible to forge or guess. This means that without your private key, the server simply won't let anyone in. This is even more convenient for the user than a password, but it provides significantly stronger protection.

2. Changing the default SSH port.

Even if your password is strong, the world is overrun with bots that simply «knock» on every available server, trying to log in. They look for standard settings, such as port 22, which is where most servers accept connections. By changing this port, you don't create an impenetrable wall, but you eliminate a huge number of automated attacks. It's very similar to a house with two entrances, but only the residents know one.

3. Setting up a firewall.

A firewall is a system of rules that controls who can access a server. It's best thought of as a virtual shield or gatekeeper that monitors which «doors» (i.e., ports) someone is attempting to access and decides whether to allow them through.

If a firewall is configured correctly, the server is only accessible to those services that are actually needed for operation. For example, it might accept website requests but completely block access to ports used only internally. You can also restrict access to administrative tools to your home IP address. This is a very effective way to reduce the risk of unauthorized access, even if an outsider knows your password or port.

4. Using Fail2Ban.

Imagine someone unsuccessfully tries to open the door to your room: first once, then twice, ten times, a hundred times. A human would try this a few times at most, but bots can continue for hours. The Fail2Ban web server protection program monitors such attempts and, upon noticing suspicious activity, simply blocks the intruder's IP address.

This is highly effective against automated attacks that try to guess passwords or test dozens of weak points on a website. Fail2Ban runs in the background, essentially acting as another security guard who not only observes but also intervenes.

5. Software updates.

Another important part of VPS server security is timely system updates. Any program eventually receives patches that close discovered vulnerabilities. Sometimes hackers discover a flaw faster than users can update. In such cases, an outdated version literally becomes an invitation for attackers.

Updating your system and installed software is the easiest way to avoid attacks due to long-known issues. It's like replacing an old lock whose weak point is known to everyone in the neighborhood.

6. Creating backup copies.

The most underrated, yet critical, aspect of security is backups. Sometimes the problem isn't caused by a hacker, but by a random error: a failed command, a failed update, running out of disk space, or even a natural disaster.

Regular backups ensure your data isn't lost forever. It's important not only to create backups automatically, but also to store them separately from the server itself. If the primary server is damaged, a backup will allow you to quickly restore everything. Essentially, it's your insurance policy, without which serious projects can't exist.

7. Monitoring.

If you don't keep an eye on what's happening on your server, you might miss the moment when things start to go wrong. By enabling monitoring logging, you can see system load, suspicious activity, unusual requests, and other signs that something isn't quite right.

Logs are a detailed «diary» of your server. If something happens, this is where you can find traces of when, where, and what exactly someone tried to do. Simply reviewing the logs, even occasionally, will help you spot potential threats early.

8. Disabling root login and restricting privileges.

Anyone who works with Linux-based operating systems probably knows that user accounts are managed using the root or sudo commands. The main problem with the root account is that it's all-powerful. If someone unauthorized gains access to it, the consequences can be catastrophic. That's why it's best to disable direct root login and create a separate administrative user.

Then all actions will be performed via sudo, which provides additional control and security. It's like having a key to a house, but the safe inside only opens through a separate procedure. Less freedom means less chance of causing harm, either accidentally or intentionally.

9. Two-factor authentication.

Imagine that in addition to your regular key, you have another unique one that changes every time. This is exactly how two-factor authentication (2FA) works. Even if someone gets your password or even your SSH key, they won't be able to access anything without the second code.

2FA adds another layer of security: when you log in, you confirm your identity by entering a one-time code from your phone. It's like having another lock that only you know about. And it always works — even when other layers of security suddenly fail.

10. DDoS protection.

A DDoS attack occurs when thousands or millions of fake visitors simultaneously bombard your server. It simply can't withstand the onslaught and stops working. To prevent this, you need additional protection: a CDN, dedicated anti-DDoS services, or even simple request rate limits at the web server level.

It's like a security guard who only lets in legitimate customers while keeping the crowds of unwanted visitors at the door. Properly configured protection helps your server remain accessible even when someone is trying to flood it with traffic.

11. Flood prevention.

Flooding is the deliberate sending of a huge number of meaningless or repetitive requests to a server in order to overload a specific service: chat, API, form, port, or even the login panel. Unlike a large-scale DDoS attack, flooding can also be local — for example, when one or more IP addresses constantly flood your server with traffic.

To protect against various types of flooding, rate limits are used—a limit on the number of requests per minute, firewall protection (UFW, CSF), and web server rules (Nginx/Apache) that block suspicious activity. This is like installing a turnstile that only allows a certain number of people through during a certain period of time, preventing crowding at the entrance.

12. Preventing malicious shell scripts from running.

Malicious shell scripts are like uninvited tenants that can sneak in via a vulnerable website, a misconfigured user, or a stolen file. Once on the server, such a shell script can execute arbitrary commands: download viruses, create backdoors, mine cryptocurrency, or use your VPS to attack other targets.

To prevent this, it's important to:

• restrict file system permissions — don't give web servers or services unnecessary capabilities;
• use antivirus software or malware scanners (ClamAV, Maldet, etc.);
• enable SELinux or AppArmor — these are like security guards that control what each process can (and cannot) do;
• monitor suspicious files and processes to spot unwanted «guests» early.

Why is it important to rent a VPS from a reliable provider?

Even a perfectly configured VPS will be more vulnerable if it runs on weak hardware or on a network without proper security. A reliable provider is the foundation on which your entire server is built.

That's why it's important to consider not only price but also infrastructure, technical support, and stability. At Maxnet, VPS hosting runs on modern equipment and high-quality communication channels, ensuring stability and a quick response in the event of any issues. This allows users to focus on work or business without worrying about the server.