You can view the documentation below, or browse our GitHub Repository, where you can contribute to user manual and FAQ.
freshclam attempts to detect potential problems with DNS caches and switches to the old mode if something looks suspicious. If this message appears seldomly, you can safely ignore it. If you get the error everytime you run freshclam, check your system clock. If it is set correctly, check your dns settings. If those didn’t help, try putting this at the top of your cronjob:
host -t txt current.cvd.clamav.net; perl -e 'printf "%d\n", time;'
The 4th field of the first line should be less than 3 ∗ 3600 behind the output of the second line. If not, you have a caching DNS server somewhere misbehaving.
The virus database is usually updated many times per week. Sign up for our VirusDB mailing list to see our response times to new threats. The virusdb team tries to keep up with the latest threats in the wild. You can contribute to make the virusdb updating process more efficient by submitting samples of viruses via our “Contact” page on ClamAV.net.
You can check for database update as often as 4 times per hour provided that you have the following options in
Before publishing a CVD update, we verify that it can be correctly loaded by the last two stable release series of ClamAV.
Before publishing a CVD update, we test it for false positives using the latest stable release of ClamAV. If you want to avoid problems with false positives, you must run the latest stable version of ClamAV.
Please run clamscan with the
--detect-broken option. Also check that freshclam and clamscan are using the same path for storing/reading the database.
Our virus database is kept up to date with the help of the community. Whenever you find a new virus which is not detected by ClamAV you should complete this form. The virusdb team will review your submission and update the database if necessary. Before submitting a new sample: - check that the value of
DatabaseDirectory, in both
freshclam.conf, is the same - update your database by running freshclam
ClamAV comes with freshclam, a tool which periodically checks for new database releases and keeps your database up to date.
There is a problem with your DNS server. Please check the entries in /etc/resolv.conf and verify that you can resolve the TXT record manually:
$ host -t txt current.cvd.clamav.net
If you can’t, it means your network is broken. You’ll be still able to download the updates, but you’ll waste a lot of bandwidth checking for updates.
Either your dns servers are not working or you are blocking port 53/tcp. You should manually check that you can resolve hostnames with:
$ host database.clamav.net
If it doesn’t work, check your dns settings in
/etc/resolv.conf. If it works, check that you can receive dns answers longer than 512 bytes, e.g. check that your firewall is not blocking packets which originate from
An easy way to find it out is:
$ dig @ns1.clamav.net db.us.big.clamav.net
Try to download daily.cvd with lynx or wget from the same machine that is running freshclam. Future versions of freshclam will provide a better way to deal with this.
mirrors.dat is used by freshclam to keep track of broken mirrors. It avoids the unnecessary delays caused by trying to download a CVD update from a mirror which failed multiple times during the last 24 hours.
Sure, you can find more details on our Mirror page.
If you want to take advantage of incremental updates, install a proxy server and then configure your freshclam clients to use it (watch for the HTTPProxyServer parameter in man freshclam.conf).
The second possible solution is to:
Configure a local webserver on one of your machines (say
Let freshclam download the
*.cvd files from http://database.clamav.net to the webserver’s DocumentRoot.
freshclam.conf on your clients so that it includes:
First the database will be downloaded to the local webserver and then the other clients on the network will update their copy of the database from it.
Important: For this to work, you have to add
ScriptedUpdates off on all of your machines!
No problem, save your own signatures in a text file with the appropriate extension. Put it in the same dir where the .cvd files are located. ClamAV will load it after the official .cvd files. You need not to sign the .db file .
Yes, the virusdb can be downloaded from the Latest releases section on our home page.
current.cvd.clamav.net has got only a TXT record, not a type A record! Try this command:
$ host -t txt current.cvd.clamav.net
Please note that some not RFC compliant DNS servers (namely the one shipped with the Alcatel (now Thomson) SpeedTouch 510 modem) can’t resolve
TXT record. If that’s the case, please recompile ClamAV with the flag