Wait, Linux needs antivirus and anti-malware solutions? I thought it was immune to such things. Perhaps a bit of clarification is necessary here.
First and foremost, no operating system is 100 percent immune to attack. Whether a machine is online or offline, it can fall victim to malicious code. Although Linux is less prone to such attacks than, say, Windows, there is no absolute when it comes to security. I have witnessed, first hand, Linux servers hit by rootkits that were so nasty, the only solution was to reinstall and hope the data backup was current. I’ve been a victim of a (very brief) hacker getting onto my desktop, because I accidentally left desktop sharing running (that was certainly an eye opener). The lesson? Even Linux can be vulnerable.
So why does Linux need tools to prevent viruses, malware, and rootkits? It should be obvious why every server needs protection from rootkits — because once you are hit with a rootkit, all bets are off as to whether you can recover without reinstalling the platform. It’s antivirus and anti-malware where admins start getting a bit confused.
Let me put it simply — if your server (or desktop for that matter) makes use of Samba or sshfs (or any other sharing means), those files will be opened by users running operating systems that are vulnerable. Do you really want to take the chance that your Samba share directory could be dishing out files that contain malicious code? If that should happen, your job becomes exponentially more difficult. Similarly, if that Linux machine performs as a mail server, you would be remiss to not include AV scanning (lest your users be forwarding malicious mail).
With all of that said, what are your options? Let’s take a look at a few tools, offered for the Linux platform, that do a good job of protecting you (and your users) from viruses, malware, and rootkits.
Without a doubt, ClamAV is the most popular option for keeping viruses off of your Linux machines and out of your shared directories. There are a few reasons why ClamAV is so popular among the Linux crowd. First, it’s open source, which in and of itself is a big win. Second, it’s very effective in finding trojans, viruses, malware, and other threats. ClamAV features a multi-threaded scanner daemon that is perfectly suited for mail servers and on-demand scanning.
ClamAV can be run from command line or it with the ClamTK GUI. Both tools are easy to use and very dependable. Installing ClamAV is simple.
For Debian-based systems:
sudo apt install clamav
For RHEL/CentOS systems:
sudo yum install epel-release
sudo yum install clamav
For Fedora-based systems:
sudo dnf install clamav
For SUSE-based systems:
sudo zypper in clamav
If you’re running a Debian-based desktop, you can install ClamTK (the GUI) with the command:
sudo apt install clamtk
There are also third-party tools that can be added (to include support for the likes of MTA, POP3, Web & FTP, Filesys, MUA, Bindings, and more).
Upon installation, the first thing you’ll want to do is update the signatures with the command sudo freshclam. Once that completes, you can scan a directory with the command:
clamscan -r -i DIRECTORY
where DIRECTORY is the location to scan. The -r option means to recursively scan and the -i options means to only print out infected files. If you work with the GUI, it’s even easier. From the GUI you can run a scan and, should ClamAV find anything, act on it (Figure 1).