Installing ClamAV on CentOS 7 and Using Freshclam

Install and Configure ClamAV on CentOS 7

Including the usage of Freshclam


To get ClamAV on CentOS installed, we have to use the EPEL repository (Extra Packages for Enterprise Linux). Fortunately, the Fedora project provides this with an easy installation. Unfortunately the default configuration is not properly working. In this post we collect some of the issues and required changes.

Let’s start with installing the EPEL support.

yum install epel-release

Next step is installing all ClamAV components.

yum install clamav-server clamav-data clamav-update clamav-filesystem clamav clamav-scanner-systemd clamav-devel clamav-lib clamav-server-systemd

The output should be similar to:

Screenshot of ClamAV being installed on CentOS 7

Installing ClamAV with help of EPEL repository

Configure SELinux for ClamAV

If you are using ClamAV on CentOS, together with SELinux, we should configure it a little bit. This way ClamAV can access all files on disk, and update its data definition files.

Enable antivirus_can_scan_system:

setsebool -P antivirus_can_scan_system 1

Screenshot to configure SELinux for ClamAV

If you don’t perform this step, Freshclam will log something like:

During database load : LibClamAV Warning: RWX mapping denied: Can't allocate RWX Memory: Permission denied

Configuration of Clam daemon

Copy a the clamd.conf template, in case you don’t have a configuration file yet.

cp /usr/share/clamav/template/clamd.conf /etc/clamd.d/clamd.conf
sed -i ‘/^Example/d’ /etc/clamd.d/clamd.conf

Change /etc/clamd.d/clamd.conf file and define if you want to run the scanner as root, or a specific user. Check your /etc/passwd file for the related Clam user.

Change the following two options:

User clamscan
LocalSocket /var/run/clamd.<SERVICE>/clamd.sock

Enable Freshclam

Freshclam helps with keeping the database of ClamAV up-to-date. First delete the related “Example” line from /etc/freshclam.conf.

cp /etc/freshclam.conf /etc/freshclam.conf.bak
sed -i ‘/^Example/d’ /etc/freshclam.conf

Check the other options in the file, and change it to your preferred settings.

Missing systemd service file

We didn’t get a systemd service file, so creating a quick file here. The process should be forking itself and start freshclam in daemon mode. In this case we configure it to check 4 times a day for new files.

Create a new file /usr/lib/systemd/system/clam-freshclam.service

# Run the freshclam as daemon
Description = freshclam scanner
After =
Type = forking
ExecStart = /usr/bin/freshclam -d -c 4
Restart = on-failure
PrivateTmp = true

Now enable and start the service.

systemctl enable clam-freshclam.service


systemctl start clam-freshclam.service

Check the status.

[root@centos7 system]# systemctl status clam-freshclam.service
clam-freshclam.service - freshclam scanner
Loaded: loaded (/usr/lib/systemd/system/clam-freshclam.service; enabled)
Active: active (running) since Thu 2015-06-11 11:09:24 CEST; 1s ago
Process: 3158 ExecStart=/usr/bin/freshclam -d -c 4 (code=exited, status=0/SUCCESS)
Main PID: 3159 (freshclam)
CGroup: /system.slice/clam-freshclam.service
└─3159 /usr/bin/freshclam -d -c 4

Change service files

By default, the service files seem to be messy and not working.

These are the files bundled:

[root@centos7 system]# ls -l /usr/lib/systemd/system/clam*
-rw-r--r--. 1 root root 136 Apr 29 20:38 /usr/lib/systemd/system/clamd@scan.service
-rw-r--r--. 1 root root 231 Apr 29 20:38 /usr/lib/systemd/system/clamd@.service

When enabling the clamd service, we would see something like this:

[root@centos7 system]# systemctl enable /usr/lib/systemd/system/clamd@.service
 Failed to issue method call: Unit /usr/lib/systemd/system/clamd@.service does not exist.

So let’s fix it. First rename the /usr/lib/systemd/system/clamd@.service file.

Rename the clamd@ file.

mv /usr/lib/systemd/system/clamd@.service /usr/lib/systemd/system/clamd.service

Now we have to change the clamd@scan service as well, as it refers to a non-existing file now. Change this line in /usr/lib/systemd/system/clamd@scan.service and remove the @ sign.

.include /lib/systemd/system/clamd@.service

Next step is changing the clamd service file /usr/lib/systemd/system/clamd.service

Description = clamd scanner daemon
After =
Type = simple
ExecStart = /usr/sbin/clamd -c /etc/clamd.d/clamd.conf --nofork=yes
Restart = on-failure
PrivateTmp = true

Move into the directory.

cd /usr/lib/systemd/system

Start all services.

[root@centos7 system]# systemctl enable clamd.service
[root@centos7 system]# systemctl enable clamd@scan.service
[root@centos7 system]# systemctl start clamd.service
[root@centos7 system]# systemctl start clamd@scan.service

Checking the status

With all these changes, ClamAV on CentOS 7 should be running now. The easiest way to check, is using the ps command and see if freshclam and clamd are running.

Useful resources for debugging are the systemctl status command, followed by the service. Then there is logging in /var/log/messages, which usually will reveal when and why something is (not) running.

More tips? Leave them in the comments!


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Lynis Enterprise screenshot to help with system hardening

This blog post is part of our Linux security series and the mission to get Linux and Unix-based systems more secure.

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Or start today with the open source security scanner Lynis (GitHub)


  • Thx a lot for this article! I searched a lot to get clamd work on CentOS 7!
    Nice greetings from Vienna!

  • AzzinarAzzinar

    Hi Mic,

    thank you very much for your posting. i have do that sequence but i have get error

    “Jul 28 09:13:10 localhost.localdomain freshclam[12408]: During database load : LibClamAV Warning: RWX mapping denied: Can’t allocate RWX Memory: Permission denied”

    the error disappear after type command “setsebool -P clamd_use_jit on”

    Best regards / Azzinar

  • Hi

    Every time I use this line sed -i ‘/^Example/d’ /etc/freshclam.conf the ‘ gets change to . and it fails and if I use the correct character I get the same error

    Any idea?

    • Copy the line manually in a text browser and replace the quotes with single ones. It might be due to WordPress.

    • Emiliano A.Emiliano A.

      You can use vim editor and remove this line with dd command

  • FelipeFelipe

    Hi there!

    Very good tutorial! I’m begginer in linux but I could follow this almost complete…
    My doubts are:
    1. You said to change this to any user I want, but which should be better for security matters, root or clamscan?
    2. sed -i ‘/^Example/d’ /etc/clamd.d/clamd.conf (What should happen after using that command?)
    3. You said to change this: LocalSocket /var/run/clamd./clamd.sock. To point I did not understand is, change what and for what value in there?

    Thank you!

    • Best is using a non-privilged user, to reduce the chance of attacks succeeding and having full permissions. The sed command will remove the “Example” line.
      The socket file should point to the right directory, which is determined by the service name in the related example.

      Did that help?

      • FelipeFelipe

        Hi, thanks for the reply!

        To be honest, no XD

        Let me clarify…
        2. sed -i ‘/^Example/d’ /etc/clamd.d/clamd.conf (What should happen after using that command?)
        This command didn’t delete the Exampe (I think…)

        When I get this point “LocalSocket /var/run/clamd./clamd.sock”, the problem is that I didn’t understood what should be changed there and under /var/run the only folder about clam is clamd.scan which there is nothing inside. It means that those socket file doesn’t exist.

        Until now that are my problems! :/

        As you can see I’m newbie… trying to lean XD

  • Robert NadonRobert Nadon

    As per above, just add this line:
    LocalSocket /var/run/clamd.scan/clamd.sock

    It will create your clamd.sock

  • Amy TebbeAmy Tebbe

    Thanks for the directions. I was able to get it working, however, I end up with 2 clamd processes running:

    # ps -ef|grep clam
    clamupd+ 11639 1 0 Nov23 ? 00:00:10 /usr/bin/freshclam -d -c 4
    clamscan 25171 1 1 09:42 ? 00:00:17 /usr/sbin/clamd -c /etc/clamd.dclamd.conf –nofork=yes
    clamscan 26210 1 99 10:02 ? 00:00:04 /usr/sbin/clamd -c /etc/clamd.dclamd.conf –nofork=yes

    stopping clamd.service will kill one and I can manually kill -9 the other process, but it always restarts another process.

    Any idea why I’m getting 2 clamd processes? Thanks.

  • mailpop3mailpop3

    Hi All,
    Thanks to Michael Boelen for this training

    Reply to friends about the following problem:
    #LocalSocket /var/run/clamd./clamd.sock

    1) Please first run the command:
    # ls ls -la /var/run/

    2) Now find the following folder clamd.???
    drwx–x—. 2 clamscan clamscan 80 Feb 01 10:27 clamd.scan

    3) Open the file /etc/clamd.d/clamd.conf

    4) Finde the line: #LocalSocket /var/run/clamd./clamd.sock
    5) Now change to: LocalSocket /var/run/clamd.scan/clamd.sock


  • Amy TsuiAmy Tsui

    I am not sure why you would need to change the name of /usr/lib/systemd/system/clamd@.service
    I assume this is a subprocess that is called when /usr/lib/systemd/system/clamd@scan.service is started

    You would run into no error if you enable and start /usr/lib/systemd/system/clamd@scan.service without renaming clamd@.service

    Thank you for your article. It was helpful.

  • Amy TsuiAmy Tsui

    if you do:

    systemctl list-unit-files –type=service

    you will see:

    clamd@.service static
    clamd@scan.service enabled

    In particular, “static” means “enabled because something else wants it”. Think by analogy to pacman’s package install reasons:
    enabled :: explicitly installed
    static :: installed as dependency
    disabled :: not installed

    So you should not need to change or enable the clamd@.service

    The dependency will just work if you enable and start clamd@scan.service

  • TheoTheo

    Nice work. Got me up and running. I wouldn’t mind a little more at the end with a few basic commands or to know if we are all set on a reboot to auto-start, how I will know if a virus is detected and such. But I can break out the manual. Their install instructions were all kinds of wrong so glad your post was here.

    • Great to be of help here and good feedback. Let’s help others: can you share the commands you used (after you got things set up)? Then I will add them to the article!

  • Chad VondraChad Vondra

    I am dealing with a constant error when the service starts. I have touched clamd.sock then chown’d the directory and the socket to clamupdate:clamupdate. Immediately after I do that it loads properly. Howewver, upon reboot when it fixes the stale socket it the service fails to start again until I re-touch and chown. Any suggestions would be great!

    Feb 1 14:24:01 mail clamd[4906]: Log file size limited to 1048576 bytes.
    Feb 1 14:24:01 mail clamd[4906]: Reading databases from /var/lib/clamav
    Feb 1 14:24:01 mail clamd[4906]: Not loading PUA signatures.
    Feb 1 14:24:01 mail clamd[4906]: Bytecode: Security mode set to “TrustSigned”.
    Feb 1 14:24:14 mail clamd[4906]: Loaded 4244905 signatures.
    Feb 1 14:24:16 mail clamd[4906]: LOCAL: Socket file /var/run/clamd.scan/clamd.sock could not be bound: Permission denied
    Feb 1 14:24:16 mail clamd: ERROR: LOCAL: Socket file /var/run/clamd.scan/clamd.sock could not be bound: Permission denied
    Feb 1 14:24:16 mail systemd: clamd.service: main process exited, code=exited, status=1/FAILURE
    Feb 1 14:24:16 mail systemd: Unit clamd.service entered failed state.

    • Check if your temporary directory is properly created via a file in /etc/tmpfiles.d/.

      You could try to force it in your service file:
      ExecStartPre=/bin/mkdir -p /var/run/clamd.scan
      ExecStartPre=/bin/chown -R clamuser:clamgroup /var/run/clamd.scan

      • KarbasKarbas

        Have the same problem. Unfortunately forcing directory creation and owner change with ExecStartPre didnt change much. Have noticed, when i manually launch /usr/sbin/clamd -c /etc/clamd.d/clamd.conf –nofork=yes – clamd starts without any errors and socket file is created.

        /etc/clamd.d/clamd.conf has the following options active:
        LogSyslog yes
        LocalSocket /var/run/clamd/clamd.sock
        User clamscan
        AllowSupplementaryGroups yes

        ls -la /var/run/clamd
        total 0
        drwxr-xr-x. 2 clamscan clamscan 40 Apr 13 11:30 .
        drwxr-xr-x. 28 root root 800 Apr 11 16:18 ..

        Any ideas?

        • LauraLaura

          I have the same problem. It is annoying. Did you managed to fix this? Thanks.

  • TemirTemir

    Hi, when i change line #LocalSocket /var/run/clamd./clamd.sock to:
    LocalSocket /var/run/clamd.scan/clamd.sock
    i get this error ” clamd: ERROR: LOCAL: Socket file /var/run/clamd.scan/clamd.sock is in use by another process.”

    can you tell me where i could make mistake?

    • Easiest step to validate this is using the lsof utility and see what process keeps it open. Let us know when you found it, so it might helps others as well.

    • ExtraCheesePlsExtraCheesePls

      If it helps… I just fixed this with killall clamd, then systemctl restart clamd.

  • Hi, thank you so much for this great article! I have the following question:

    How would I configure clamav to automatically kick off a weekly virus scan of the entire hard drive?

    Thanks in advanced!

  • Hello ~ thank you for this great article.

    Now that I have all 3 services up and running, is it possible for me to create an automated weekly scan of the full hard drive (or at least the important areas of the drive)?

    Thank you!

    • Hi Jason. Sure, you could run the clamscan utility to do a full system scan. Add it to your cronjobs (or timers).

  • RobertRobert

    The freshclam works fine, but when I follow the instructions above here for clamd, it won’t start. When I call the status with: systemctl status clamd.service I see the following:

    | > /usr/lib/systemd/system |->systemctl status clamd.service
    ● clamd.service – clamd scanner daemon
    Loaded: loaded (/usr/lib/systemd/system/clamd.service; enabled; vendor preset: disabled)
    Active: failed (Result: start-limit) since Sun 2016-02-14 21:52:10 CET; 6min ago
    Process: 16999 ExecStart=/usr/sbin/clamd -c /etc/clamd.d/clamd.conf –nofork=yes (code=exited, status=1/FAILURE)
    Main PID: 16999 (code=exited, status=1/FAILURE)

    Feb 14 21:52:10 systemd[1]: Unit clamd.service entered failed state.
    Feb 14 21:52:10 systemd[1]: clamd.service failed.
    Feb 14 21:52:10 systemd[1]: clamd.service holdoff time over, scheduling restart.
    Feb 14 21:52:10 systemd[1]: start request repeated too quickly for clamd.service
    Feb 14 21:52:10 systemd[1]: Failed to start clamd scanner daemon.
    Feb 14 21:52:10 systemd[1]: Unit clamd.service entered failed state.
    Feb 14 21:52:10 systemd[1]: clamd.service failed.

    Can someone tell me what is going wrong here? I Get the same error when i want to start clamd@scan

  • James DanielJames Daniel

    Hi Michael. This post includes a big error, the service is not missing and didn’t need to be created. Take a look here, it’s solved my problems:

    • Thanks, that might be helpful for others. Not everyone will do their installation the same way, so keeping things up for readers to consider what option they prefer.

      • DenisDenis

        update your blog post, no need to remove or change clamd@.service is the service template file, it means you can run few different config files. thats why it has “%i” inside. you name config and you start the service. for example 1 – /etc/clam.d/monitor.conf -> service clamd@monitor start
        example 2 – /etc/clam.d/mailscan.conf -> service clamd@mailscan start

        first one will monitor folders with on-access feature, and run as root user, the second will be using together with milter socket to scan incoming e-mails, runnind as clamscan user. and so on…



  • KennyKenny

    Why exactly are creating a freshclam daemon?

    The default clamav package creates a CRON file (namely “/etc/cron.d/clamav-update”) that calls “/usr/share/clamav/freshclam-sleep” every three hours. Creating an additional freshclam daemon by hand seems to be a bit redundant to me.


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