How to Scan for Malware with `ClamAV` on Arch Linux

Malware threats are not exclusive to Windows systems. While Linux is known for its strong security model, it’s not immune to malicious software, especially on servers, shared environments, or systems that interact with Windows users. Whether you’re an Arch Linux enthusiast running a personal desktop or managing a file server, knowing how to scan for malware can be an essential part of your security strategy.

One of the most trusted open-source antivirus tools for Linux is ClamAV. In this article, we’ll explore how to install, configure, and use ClamAV to scan your Arch Linux system for malware effectively.

What is ClamAV?

ClamAV (Clam AntiVirus) is an open-source antivirus engine designed for detecting trojans, viruses, malware, and other malicious threats. It is widely used on mail servers and Linux-based systems for file scanning and integration into custom applications.

ClamAV includes:

• A command-line scanner (clamscan)
• A daemon for faster scanning (clamd)
• A database updater tool (freshclam)
• Support for various archive formats (ZIP, RAR, GZIP, etc.)
• A robust signature-based malware detection engine

Why Use ClamAV on Arch Linux?

Arch Linux, being a rolling-release distribution, is known for its bleeding-edge packages and configurability. While it is primarily used by power users, securing your system with malware detection is just as important as any other distro.

Common scenarios where ClamAV is useful on Arch Linux:

• Running a mail or file server
• Sharing files with Windows or macOS systems
• Using Arch as a penetration testing system
• Scanning USB drives or downloaded files

Step 1: Installing ClamAV on Arch Linux

ClamAV is available in the official Arch Linux repositories.

Open a terminal and install it using pacman:

sudo pacman -S clamav

This installs the core ClamAV components:

• clamscan: On-demand scanner
• freshclam: Virus database updater
• clamd: Optional scanning daemon (for higher performance and integration)

Step 2: Configuring ClamAV

After installation, you need to configure ClamAV before using it.

1. Configure freshclam for Database Updates

freshclam keeps ClamAV’s virus database up to date. First, edit its configuration file:

sudo nano /etc/freshclam.conf

Look for this line:

Example

Comment it out by adding a # at the beginning:

#Example

Save and exit (Ctrl+O, Enter, then Ctrl+X).

2. Update the Virus Database

Before scanning, update the virus definitions:

sudo freshclam

If everything is set up correctly, it will download the latest virus database. This step is crucial because ClamAV relies on its signature database to detect malware.

Step 3: Scanning with ClamAV

You can use clamscan for on-demand scanning. It has a rich set of options that allow flexibility.

1. Scan a Specific File

clamscan filename

Example:

clamscan ~/Downloads/suspicious-file.tar.gz

2. Scan a Directory

clamscan -r /path/to/directory

The -r option means recursive scanning.

Example:

clamscan -r ~/Documents

3. Display Only Infected Files

To reduce clutter and only show infected files:

clamscan -r --infected /path/to/directory

4. Move or Remove Infected Files

ClamAV can take action on infected files:

• Move infected files to a quarantine directory:

clamscan -r --move=/home/user/quarantine /path/to/scan

• Remove infected files (use with caution):

clamscan -r --remove /path/to/scan

⚠️ Warning: Be very careful when using --remove, as it will delete infected files permanently.

Step 4: Using the ClamAV Daemon (clamd) (Optional)

For faster and repeated scans, you can use the ClamAV daemon (clamd). It’s especially useful for system integration or real-time scanning (though real-time support is limited on Linux without third-party tools).

1. Configure clamd

Edit the daemon configuration file:

sudo nano /etc/clamav/clamd.conf

Again, comment out the line:

Example

Change or verify:

• LocalSocket path (used by clamdscan)
• LogFile location
• PidFile location

Make sure the paths are writable by the ClamAV user.

Save and exit.

2. Start and Enable the ClamAV Daemon

sudo systemctl enable clamav-daemon --now

Verify it’s running:

systemctl status clamav-daemon

3. Scan Using clamdscan

With clamd running, you can now use clamdscan for faster scanning:

clamdscan /path/to/scan

It uses the daemon’s preloaded database and runs faster than clamscan.

Step 5: Automating Regular Scans

It’s good practice to schedule periodic scans and database updates.

1. Automate Database Updates with systemd Timer

Enable and start the freshclam systemd timer:

sudo systemctl enable clamav-freshclam.timer --now

This ensures virus definitions are updated automatically.

2. Schedule Scans with cron or systemd

Example cron job (run daily at 2 AM):

crontab -e

Add:

0 2 * * * clamscan -r --infected /home/user > /home/user/clamav-scan.log

Or use a systemd timer for better integration with modern systems.

Step 6: Interpreting Scan Results

ClamAV reports infected files like this:

/home/user/Downloads/malware.exe: Win.Trojan.Generic FOUND

The format:

• File path
• Malware name
• Status: FOUND

A summary is shown at the end:

----------- SCAN SUMMARY -----------
Known viruses: 8700000
Engine version: 1.2.0
Scanned directories: 12
Scanned files: 110
Infected files: 1
Data scanned: 30.45 MB
Time: 0.871 sec (0 m 0 s)

Tips and Best Practices

• Regularly update signatures: New threats are added to the ClamAV database frequently.
• Scan new downloads or USB drives: Especially files from untrusted sources.
• Use with email/file servers: ClamAV is highly efficient at scanning mail attachments and file uploads.
• Consider multi-engine scanners: If security is critical, use ClamAV alongside tools like chkrootkit, rkhunter, or commercial antivirus engines.

Limitations of ClamAV

ClamAV is a great open-source option, but it has limitations:

• No real-time protection out of the box
• Heuristic and behavior-based detection is limited
• Not as comprehensive as commercial antivirus tools

Despite these, it remains a powerful utility for on-demand scanning, especially on Linux systems.

Conclusion

Using ClamAV on Arch Linux provides an effective way to detect and handle malware on your system. Whether you’re using Arch for daily work, as a server, or part of a security toolkit, incorporating ClamAV can help reduce your exposure to threats.

By installing, configuring, and scheduling regular scans, you can ensure that your system is monitored for malicious files — and remain a step ahead of potential vulnerabilities.

For advanced users, combining ClamAV with other tools or integrating it into scripts and monitoring solutions can take your security posture even further.