Clam AntiVirus is an open source (GPL) anti-virus toolkit for UNIX. It provides a number of utilities including a flexible and scalable multi-threaded daemon, a command line scanner and advanced tool for automatic database updates. Because ClamAV's main use is on file/mail servers for Windows desktops it primarily detects Windows viruses and malware.
- 1 Installation
- 2 Updating database
- 3 Starting the daemon
- 4 Testing the software
- 5 Adding more databases/signatures repositories
- 6 Scan for viruses
- 7 Using the milter
- 8 Troubleshooting
ClamAV can be installed with package .
Update the virus definitions with:
The database files are saved in:
/var/lib/clamav/daily.cvd /var/lib/clamav/main.cvd /var/lib/clamav/bytecode.cvd
The virus definition updater service is called
freshclamd.service. Consider starting it and enabling it to start at boot so that the virus definitions are kept recent.
Starting the daemon
Consider updating the database before starting the service for the first time or you will run into troubles/errors which will prevent ClamAV to start correctly.
Testing the software
In order to make sure ClamAV and the definitions are installed correctly, scan the EICAR test file (a harmless signature with no virus code) with clamscan.
$ curl http://www.eicar.org/download/eicar.com.txt | clamscan -
The output must include:
stdin: Eicar-Test-Signature FOUND
Otherwise; read the Troubleshooting part or ask for help in the Arch Forums.
Adding more databases/signatures repositories
ClamAV can use databases/signature from other repositories or security vendors.
To add the most important ones in a single step install
This will add signatures/databases from e.g. MalwarePatrol, SecuriteInfo, Yara, Linux Malware Detect,...
Scan for viruses
clamscan can be used to scan certain files, home directory, or an entire system:
$ clamscan myfile $ clamscan --recursive --infected /home # or -r -i $ clamscan --recursive --infected --exclude-dir='^/sys|^/dev' /
If you would like
clamscan to remove the infected file add to the command the
--remove option, or you can use
--move=/dir to quarantine them.
You may also want
clamscan to scan larger files. In this case, append the options
--max-scansize=4000M to the command. '4000M' is the largest possible value, and may be lowered as necessary.
-l /path/to/file option will print the
clamscan logs to a text file for locating reported infections.
Using the milter
/etc/clamav/clamav-milter.conf and adjust it to your needs. For example:
MilterSocket /run/clamav/clamav-milter.sock MilterSocketMode 660 FixStaleSocket yes User clamav PidFile /run/clamav/clamav-milter.pid TemporaryDirectory /tmp ClamdSocket unix:/var/lib/clamav/clamd.sock LogSyslog yes LogInfected Basic
[Unit] Description='ClamAV Milter' After=clamd.service [Service] Type=forking ExecStart=/usr/bin/clamav-milter --config-file /etc/clamav/clamav-milter.conf [Install] WantedBy=multi-user.target
Enable and start the service.
Error: Clamd was NOT notified
If you get the following messages after running freshclam:
WARNING: Clamd was NOT notified: Cannot connect to clamd through /var/lib/clamav/clamd.sock connect(): No such file or directory
Add a sock file for ClamAV:
# touch /var/lib/clamav/clamd.sock # chown clamav:clamav /var/lib/clamav/clamd.sock
/etc/clamav/clamd.conf - uncomment this line:
Save the file and restart the daemon
Error: No supported database files found
If you get the next error when starting the daemon:
LibClamAV Error: cli_loaddb(): No supported database files found in /var/lib/clamav ERROR: Not supported data format
This happens because of mismatch between
/etc/freshclam.conf pointing to
/etc/clamd.conf (default directory) pointing to
/usr/share/clamav, or other directory. Edit in
/etc/clamd.conf and replace with the same DatabaseDirectory like in
/etc/freshclam.conf. After that clamav will start up succesfully.
Error: Can't create temporary directory
If you get the following error, along with a 'HINT' containing a UID and a GID number:
# can't create temporary directory
# chown UID:GID /var/lib/clamav & chmod 755 /var/lib/clamav