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The core problem with this approach is that antivirus scanning is generally based on signature recognition of malicious binaries. Behavior-based antivirus scanning mostly doesn’t work and tends to generate a lot of false positives. No freely available antivirus is going to have a signature library that is kept up to date enough to be worth the effort of running it on Linux - most vulnerabilities are going to be patched long before a free service gets around to creating a signature for malware that exploits those vulnerabilities, at which point the signature would be moot. If you want antivirus that is kept up to date on a weekly or better basis, you’re going to have to pay for a professional service.

That said, there are other, simpler (and probably more effective) options for hardening your systems:

• Firewall - if your servers are dedicated to specific services and you don’t plan on adding many more applications, you should be able to tighten up their firewalls to have only the ports they need open and nothing else. If network security is a priority, you should start with this.
• Application Whitelisting - prevent unrecognized applications from running. There are more options for this on Windows (including the builtin Applocker), but there are some AWL options for Linux. It’s a lot easier to recognize the things that you do want to run than all of the things that you don’t want to run.
• Secure OS - I assume you’re using Debian because it’s familiar, but it is a general-purpose OS with a broad scope. Consider switching to a more stripped-down variant like Alpine Linux (it can be installed on a Pi).

Behavior-based antivirus is extremely difficult, failure-prone, and almost entirely unnecessary because of how secure Linux is, so they don’t exist to my knowledge. Signature-based antivirus is basically useless because any security holes exploited by a virus are patched upstream rather than waiting for an antivirus to block it. ClamAV focuses on Windows viruses, not Linux ones, so it can be a signature-based antivirus, but not many people run an email server accessed by Windows devices or other similar services that require ClamAV, so not many people use it, and nobody made any alternatives.

If you’re worried about security, focus on hardening and updates, not antiviruses.

Okay, I think we can wrap this up: OP started with “I don’t want to be convinced of the predominant oppinion about security” and kept their word.
OP: You got your answer. There is no alternative to ClamAV. ClamAV is open source so it will always be slower than apt update in fixing vulnerabilities.
You can wonder why the whole community that created tons and tons of cool shit for Linux with armies of talented people with way more IT knowledge than all of us combined didn’t dedicate their time to Viruses. You can ask yourself how a virus would even get on your server… or you can not. Your choice. But the answer is: There is no alternative to ClamAV and ClamAV is set up mainly to detect Windows-Viruses that get spread by Mail-Attachments and the like.

I also use ClamAV, but only in specific circumstances, such as when a Linux server will be hosting end-user files. Perhaps a SAMBA server with a file share, or a web server which accepts user uploads.
In those cases, I might want to have it monitor the relevant part of the disk, but I also need to make sure my web application won’t fall over when the file it just accepted is unceremoniously ripped away from it. You can test that out using the EICAR file as your payload.
On a jump box, I might also have it turned on for scanning user home directories, by including /home, and then excluding any home directories for applications and daemons which might not deal well with having their IOPS nuked or delayed.

I would recommend just setting up iptables & crowdsec. Open only the ports your services need, and add the relevant plugins to crowdsec. Nothing should come through.

If you have services that allow people to upload files, that’s a different story.

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I am not a expert in Linux, and I mostly rely on very strong passwords. I also discovered recently basic stuff like changing the default SSH port. Anyone knows of implementation of 2FA on Linux?

Maybe you’d be interested in https://wazuh.com/

There are none. ClamAV is the only one there is, because it has a very specific and narrow purpose. There are no viruses for Linux.

Chrootkit and rkhunter are also built for very specific things (detecting rootkits - or making them) and are not designed to protect, they are designed to analyse.

My writing here also isn’t specifically to OP, but to all others that may find this thread - Anti Virus for Linux is BS and unless you are running SMB and still have lots of Windows in your network, it’s absolutely not needed, especially if you follow the basics (like not doing stuff as root, using sudo and not giving out any system rights).

Honestly, the best antivirus for Linux is Arch.