Updating Antivirus for Linux

For full Linux-related documentation, see Avast Business Antivirus for Linux Technical Guide.

VPS Updates

Note that the VPS updates for any legacy Antivirus versions still running on 32-bit operating systems will be discontinued during 2023 (see Antivirus for Linux Legacy Information).

In order to keep your protection up to date, you must regularly update the virus definitions database (VPS). Avast Business Antivirus provides a shell script which checks for, downloads, and installs the latest VPS. The update script is installed by default and executed every three hours as a systemd timer.

Avast uses incremental updates, so the average update data size is less than 0.5 MB.

Local Virus Definitions Mirrors

It is possible to use a local, mirrored, VPS repository. This is useful when you are running several Avast installations on your local network. To set up a local VPS mirror, you need a local HTTP server that can serve a copy of the official public repository. To get your local repository copy, use the following command:

• $ wget --mirror --no-host-directories --cut-dirs=2 \ "http://linux-av.u.avcdn.net/linux-av/avast/x86_64/vps9/"
  • Replace x86_64 with i386 for 32-bit systems

To change the VPS repository URL that Avast uses for VPS updates, edit the /etc/avast/vps.conf configuration file.

Deleting Old Virus Definitions Files

Local Device

If you are not using an update mirror, the deletion of the virus definitions files will be automatic, i.e. requiring no user intervention. If, however, you notice that the virus definitions folder is not being cleared automatically, manually delete all files except the latest version installed, then reboot the device. If the issue reoccurs, please collect the system logs (/var/log/system.log) and send them to the Avast Business Support team for analysis.

Update Mirror

If you are using an update mirror, you will need to periodically clean the mirror's virus definitions folder. One way to do this would be deleting old virus definitions files manually. Alternatively, you can schedule automatic deletions by adding a cron job to the crontab. Using a cron job would allow you to configure the deletion occurrence (e.g. monthly) as well as to specify the files to be deleted (to avoid deleting the latest version).

For example, to create a cron job that would run every first of the month at midnight to detect and delete all virus definitions files older than 15 days, use the following command:

• 0 0 1 * * find <path to vps9 folder > -mtime +15 -delete

Security Considerations

Update files are signed by Avast, and the application verifies the signature before applying an update.