Installing
Both ClamAV and its updates are made available free of charge. ClamAV is a powerful AntiVirus scanner focused towards integration with mail servers for attachment scanning. It provides a flexible and scalable multi-threaded daemon, a command line scanner, and a tool for automatic updating via the Internet. FOUND$/m , # NOTE: run clamd under the same user as amavisd - or run it under its own # uid such as clamav, add user clamav to the amavis group, and then add # AllowSupplementaryGroups to clamd.conf; # NOTE: match socket name (LocalSocket) in clamav.conf to the socket name in # this entry; when running chrooted one may prefer a socket under. The clamav-daemon package creates a 'clamav' user; in order to allow ClamAV to scan system files, such as your mail spool, you can add clamav to the group that owns the files. Let ClamAV listen for Incoming Scans. There are cases where you may want ClamAV daemon to act as a scanner for other systems, so you don't have to run everything locally. To use it via a REST proxy like @solita made clamav-rest or; to directly connect to clamav via TCP port 3310; ClamAV daemon as a Docker image. It builds with a current virus database and runs freshclam in the background constantly updating the virus signature database. Clamd itself is listening on exposed port 3310. Memorandum: How to build ClamAV® - antivirus scanning engine on Mac OS X 10.4 through macOS 10.13, Compile ClamAV on Mac OS X 10.4, Mac OS X 10.5, Mac OS X 10.6, Mac OS X 10.7, OS X 10.8, OS X 10.9, OS X 10.10, OS X 10.11, macOS 10.12, macOS 10.13, macOS 10.14, macOs 10.15, macOs 11.0, Running clamd and freshclam as 'launch daemon', Running RunFreshclam as 'launch daemon', Running ClamXav.
ClamAV can be found for Ubuntu in the apt repository. Run this command to install ClamAV:
apt-get install clamav
If you need clamd, you may also want to run:
apt-get install clamav-daemon
If you require support for scanning compressed RAR files you first need to enable the non-free archive, and then you can install the RAR-plugin using:
apt-get install libclamunrar6
There are two classes of clamav packages available for Ubuntu users:
Released Set
The released set (release, *-updates, and *-security) are patched for security updates. Following extensive testing of clamav and the packages that use it in the backports repository, they may be updated to a newer version. These are official Ubuntu packages and supported by community developers.
Backports
The Ubuntu backports repository will contain the newest clamav version that has been at least lightly tested to work with that version. These packages can be installed by enabling the backports repository on your system.
Ubuntu packages are maintained by Ubuntu MOTU Developers.
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 with its built-in signatures.
Installation
Install the clamav package.
Updating database
Update the virus definitions with:
If you are behind a proxy, edit /etc/clamav/freshclam.conf
and update HTTPProxyServer, HTTPProxyPort, HTTPProxyUsername and HTTPProxyPassword.
The database files are saved in:
Start/enableclamav-freshclam.service
so that the virus definitions are kept recent.
Starting the daemon
Note:- You will need to run
freshclam
before starting the service for the first time or you will run into trouble/errors which will prevent ClamAV from starting correctly. - The daemon is not needed if you only want to perform stand-alone scans. See Scan for viruses below.
The service is called clamav-daemon.service
. Start it and enable it to start at boot.
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.
The output must include:
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 either clamav-unofficial-sigsAUR (see GitHub description) or python-fangfrischAUR (see online documentation). Both will add signatures/databases from popular providers, e.g. MalwarePatrol, SecuriteInfo, Yara, Linux Malware Detect, etc.
clamav-freshclam.service
started in order to have official signature updates from ClamAV mirrors.Option #1: Set up Fangfrisch
Fangfrisch was designed as a more secure, flexible and convenient replacement for clamav-unofficial-sigs, and requires very little configuration.
Most importantly, Fangfrisch never needs to be run with root permissions, unlike clamav-unofficial-sigs.
Create database structure by running:
Enable the fangfrisch.timer
.
Option #2: Set up clamav-unofficial-sigs
Enable the clamav-unofficial-sigs.timer
.
This will regularly update the unofficial signatures based on the configuration files in the directory /etc/clamav-unofficial-sigs
.
To update signatures manually, run the following:
To change any default settings, refer and modify /etc/clamav-unofficial-sigs/user.conf
.
MalwarePatrol database
If you would like to use the MalwarePatrol database, sign up for an account at https://www.malwarepatrol.net/free-guard-upgrade-option.
In /etc/clamav-unofficial-sigs/user.conf
, change the following to enable this functionality:
Source: https://www.malwarepatrol.net/clamav-configuration-guide/
Scan for viruses
There are two options for on-demand scanning:
using the stand-alone scanner
clamscan
can be used to scan certain files, home directories, or an entire system:
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-filesize=4000M
and --max-scansize=4000M
to the command. '4000M' is the largest possible value, and may be lowered as necessary.
Using the -l /path/to/file
option will print the clamscan
logs to a text file for locating reported infections.
using the daemon
clamdscan
is similar to the above but utilizes the daemon, which must be running for the command to work. Most options are ignored since the daemon reads the the settings specified in /etc/clamav/clamd.conf
.
Clamav For Linux
Using the milter
Milter will scan your sendmail server for email containing virus.Adjust the config /etc/clamav/clamav-milter.conf
to your needs. For example:
Create /etc/systemd/system/clamav-milter.service
:
Enable and startclamav-milter.service
.
For Postfix add the following lines to /etc/postfix/main.cf
:
Check journalctl if the permission to access clamav-milter.socket for postfix is set accordingly, if not, add user postfix to group clamav.
OnAccessScan
This article or section is out of date.
On-access scanning requires the kernel to be compiled with the fanotify kernel module (kernel >= 3.8). Check if fanotify has been enabled before enabling on-access scanning.
On-access scanning will scan the file while reading, writing or executing it.
First, edit the /etc/clamav/clamd.conf
configuration file by adding the following to the end of the file (you can also change the individual options):
Next, create the file /etc/clamav/detected.sh
and add the following. This allows you to change/specify the debug message when a virus has been detected by clamd's on-access scanning service:
If you are using AppArmor, it is also necessary to allow clamd to run as root:
Restart the clamav-daemon.service
.
Source: http://blog.clamav.net/2016/03/configuring-on-access-scanning-in-clamav.html
Troubleshooting
Error: Clamd was NOT notified
If you get the following messages after running freshclam:
Add a sock file for ClamAV:
Then, edit /etc/clamav/clamd.conf
- uncomment this line:
Save the file and restartclamav-daemon.service
.
Error: No supported database files found
If you get the next error when starting the daemon:
This happens because of mismatch between /etc/clamav/freshclam.conf
setting DatabaseDirectory
and /etc/clamav/clamd.conf
setting DatabaseDirectory
. /etc/clamav/freshclam.conf
pointing to /var/lib/clamav
, but /etc/clamav/clamd.conf
(default directory) pointing to /usr/share/clamav
, or other directory. Edit in /etc/clamav/clamd.conf
and replace with the same DatabaseDirectory like in /etc/clamav/freshclam.conf
. After that clamav will start up successfully.
clamav-freshclam.service
started in order to have official signature updates from ClamAV mirrors.Option #1: Set up Fangfrisch
Fangfrisch was designed as a more secure, flexible and convenient replacement for clamav-unofficial-sigs, and requires very little configuration.
Most importantly, Fangfrisch never needs to be run with root permissions, unlike clamav-unofficial-sigs.
Create database structure by running:
Enable the fangfrisch.timer
.
Option #2: Set up clamav-unofficial-sigs
Enable the clamav-unofficial-sigs.timer
.
This will regularly update the unofficial signatures based on the configuration files in the directory /etc/clamav-unofficial-sigs
.
To update signatures manually, run the following:
To change any default settings, refer and modify /etc/clamav-unofficial-sigs/user.conf
.
MalwarePatrol database
If you would like to use the MalwarePatrol database, sign up for an account at https://www.malwarepatrol.net/free-guard-upgrade-option.
In /etc/clamav-unofficial-sigs/user.conf
, change the following to enable this functionality:
Source: https://www.malwarepatrol.net/clamav-configuration-guide/
Scan for viruses
There are two options for on-demand scanning:
using the stand-alone scanner
clamscan
can be used to scan certain files, home directories, or an entire system:
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-filesize=4000M
and --max-scansize=4000M
to the command. '4000M' is the largest possible value, and may be lowered as necessary.
Using the -l /path/to/file
option will print the clamscan
logs to a text file for locating reported infections.
using the daemon
clamdscan
is similar to the above but utilizes the daemon, which must be running for the command to work. Most options are ignored since the daemon reads the the settings specified in /etc/clamav/clamd.conf
.
Clamav For Linux
Using the milter
Milter will scan your sendmail server for email containing virus.Adjust the config /etc/clamav/clamav-milter.conf
to your needs. For example:
Create /etc/systemd/system/clamav-milter.service
:
Enable and startclamav-milter.service
.
For Postfix add the following lines to /etc/postfix/main.cf
:
Check journalctl if the permission to access clamav-milter.socket for postfix is set accordingly, if not, add user postfix to group clamav.
OnAccessScan
This article or section is out of date.
On-access scanning requires the kernel to be compiled with the fanotify kernel module (kernel >= 3.8). Check if fanotify has been enabled before enabling on-access scanning.
On-access scanning will scan the file while reading, writing or executing it.
First, edit the /etc/clamav/clamd.conf
configuration file by adding the following to the end of the file (you can also change the individual options):
Next, create the file /etc/clamav/detected.sh
and add the following. This allows you to change/specify the debug message when a virus has been detected by clamd's on-access scanning service:
If you are using AppArmor, it is also necessary to allow clamd to run as root:
Restart the clamav-daemon.service
.
Source: http://blog.clamav.net/2016/03/configuring-on-access-scanning-in-clamav.html
Troubleshooting
Error: Clamd was NOT notified
If you get the following messages after running freshclam:
Add a sock file for ClamAV:
Then, edit /etc/clamav/clamd.conf
- uncomment this line:
Save the file and restartclamav-daemon.service
.
Error: No supported database files found
If you get the next error when starting the daemon:
This happens because of mismatch between /etc/clamav/freshclam.conf
setting DatabaseDirectory
and /etc/clamav/clamd.conf
setting DatabaseDirectory
. /etc/clamav/freshclam.conf
pointing to /var/lib/clamav
, but /etc/clamav/clamd.conf
(default directory) pointing to /usr/share/clamav
, or other directory. Edit in /etc/clamav/clamd.conf
and replace with the same DatabaseDirectory like in /etc/clamav/freshclam.conf
. After that clamav will start up successfully.
Error: Can't create temporary directory
If you get the following error, along with a 'HINT' containing a UID and a GID number:
Correct permissions:
Tips and tricks
Run in multiple threads
Using clamscan
When scanning a file or directory from command line using clamscan
only single CPU thread is used. This may be ok in cases when timing is not critical or you do not want computer to become sluggish. If there is a need to scan large folder or USB drive quickly you may want to use all available CPUs to speed up the process.
clamscan
is designed to be single-threaded, so xargs
can be used to run the scan in parallel:
In this example the -P
parameter for xargs
runs clamscan
in as many processes as there are CPUs (reported by nproc
at the same time. --max-lines
and --max-args
options will allow even finer control of batching the workload across the threads.
Using clamdscan
If you already have clamd
daemon running clamdscan
can be used instead (see #Starting the daemon):
Clamav For Mac
Here the --multiscan
parameter enables clamd
to scan the contents of the directory in parallel using available threads. --fdpass
parameter is required to pass the file descriptor permissions to clamd
as the daemon is running under clamav
user and group.
The number of available threads for clamdscan
is determined in /etc/clamav/clamd.conf
via MaxThreads
parameter clamd.conf(5). Even though you may see that the number of MaxThreads
specified is more than one (current default is 10), when you start the scan using clamdscan
from command line and do not specify --multiscan
option, only one effective CPU thread will be used for scanning.