One of the easiest but oft-forgotten Linux security habits is simply staying current. I’ve had people wait weeks to update the kernel, then find later that a widely publicized bug had been exploited. Your package manager is your friend, so if you use apt, dnf, or pacman, don’t ignore those update notifications.
There are also automatic tools like dnf-automatic or unattended-upgrades that can update automatically for you, especially in those servers that you may not be visiting on a daily basis. Having a break after update is better than malware silently compromising your system.
Limit Who Keeps the Keys
Root power is powerful, and potentially catastrophic if wielded by the wrong person. One of the Linux best practices that I consistently reinforce to my students is the principle of least privilege. Grant the user only what he or she really needs. Most users won’t need access to sudo, and in the cases where the user will need it, the /etc/sudoers file can be edited to institute finely graded rules.
When I worked in a group study environment, one improperly set permission one day gave one user the capability to delete other researchers’ projects. We fixed it in a rush, but it was a lesson early on that even a small slip can snowball.
Establish a Proper Firewall and Secure SSH
A firewall is essential. Use ufw, iptables, or firewalld to close all the ports that one doesn’t need and lock down important services. These packages need to be installed immediately after the installation. You will be amazed how many ports are open in a new installation.
And SSH, of course. Disable root-login. Use key authentication. If it’s appropriate for your setup, change the port. And, of course, fail2ban install. It’s far from a silver bullet, but it reduces brute force by a significant amount.
Keep Looking: Even When Your Eyes Aren’t
You cannot fix what you cannot see. One of the frequently neglected Linux security best practices is keeping an eye on logs. Three programs that will keep you informed of login attempts, errors, and mismatches are logwatch, journalctl, and rsyslog.
In one of my previous projects, I had set up AIDE (Advanced Intrusion Detection Environment) to watch for file modifications. It caught the altered.bash_profile that was a backdoor. It would not have caught it if I had not set it to notify me of it.
And a side point for creators hosting their own servers: while keeping unauthorized access is crucial to the well-being of your server, keeping watch hours in mind is similarly crucial to keeping your content in view. Failing to heed either of those is risky.
Encrypt Everything that Matters
Encryption is one of the cornerstones of Linux best practices in terms of security. Use full-disk encryption using LUKS during installation for full protection. Use GPG or encfs to encrypt sensitive directories or single files as needed. And send data using secure methods. SCP, SFTP, or rsync over SSH rather than plain FTP. Web servers? Use SSL/TLS certificates by implementing letsencrypt or other registrars. It doesn’t cost anything and earns you that green padlock, which is a dealbreaker these days.
Turn off what you can live without
Minimalism is underrated in server configurations. Each service you’ve running is a potential vulnerability waiting to happen. Use nmap or netstat to scan your system for what’s open and kill whatever is unecessary using systemctl.
While working on a freelance project, I’ve already come across a client’s staging server hosting an extremely outdated mail daemon that they didn’t even utilize. It was left wide open. It took less than a minute to remove but likely averted a serious data leak.
Always Backup, Always Verify
One of the less-discussed Linux security best practices is backing up your data. It isn’t that you simply need to have a backup, though, even that would be better than nothing. Rather, you need to have a confirmed, restorable one. I use utilities like rsync for fast syncs, and BorgBackup or Restic for encrypted backups.
Regularly testing backups is critical. I’ve had pupils come to me after a ransomware attack, to find their backups were either corrupt or incomplete. Don’t be one of them.
Take Control using AppArmor or SELinux
AppArmor and SELinux, which are mandatory access controls, are quite strong yet greatly underutilized. AppArmor comes pre-installed if you are working on Debian or Ubuntu-based systems. SELinux is the one that rules in a Red Hat environment. Yes, it is correct that there is a steep learning curve. But the investment in writing or adapting policies pays off. These tools give you a level of safeguards that can seal on damage even if you breach a service.
FAQs
Why is Linux considered more secure than other operating systems?
Linux is open-source, which allows for more community-based auditing. It also separates user permissions more strictly by default compared to some other OSs.
Can I use antivirus software on Linux?
You can, especially for mail servers or file servers that interact with Windows systems. Tools like ClamAV are available, but they’re more of a supplement than a necessity.
What’s the first thing I should secure after installing Linux?
Update the system, configure your firewall, and lock down SSH access. These steps form the bedrock of most Linux security best practices.