The up-to-date virus signature files for the ClamAV antivirus, which can be downloaded in case the Freshclam updater cannot connect to the Internet
Using an antivirus to protect your computer against threats is useless if you don't keep the virus definitions up-to-date. The signature database contains information about the latest threats and allows the security tool to identify potentially suspicious files correctly.
All antivirus solutions deploy integrated updaters to download the latest virus signatures and ClamAV (Clam Antivirus) makes no exception. The only twist is that, this time, the updater runs as a console application named "freshclam", just like the ClamAV engine. The ClamAV manual contains instructions on how to set up this application. Needless to say, an active Internet connection in mandatory for the updater to be able to contact the ClamAV servers.
However, if you find yourself in a situation when you need to update ClamAV's signatures and no Internet connection is available, then the offline virus databases will surely serve you well. The ClamAV Virus Databases contain a package of updated virus definitions that you can use in case your computer goes offline.
There are three different virus databases, namely the daily signatures, the main and the bytecode signatures. The last two are, obviously, updated more rarely than the first.
To use them, all you have to do is create a "database" folder inside the installation directory of ClamAV and place them inside. It is advisable you take the time to configure the Freshclam app beforehand, as otherwise you might get a warning stating that the updater and the configuration files of the antivirus do not point to the same virus database.
ClamAV Virus Databases is part of these download collections: Virus Definitions