You can view the documentation below, or browse our GitHub Repository, where you can contribute to user manual and FAQ.
The following FAQ should help you understand why
freshclam may have failed to fetch the latest updates.
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. 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
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
port 53/tcp. An easy way to find it out is:
$ dig @ns1.clamav.net db.us.big.clamav.net
For some reason, the mirror didn’t fetch the cdiff file. Freshclam can recover from this situation by trying the next mirror.
For some reason, incremental update failed. Freshclam can recover from this situation by downloading the whole daily.cvd.
For some reason, this mirror has not fetched the latest updates yet. If you experience this problem, please report the issue on Bugzilla.
It’s not your lucky day. Freshclam tried every possible way to download the updates but failed. Usually this means that all the mirrors in your local pool are down or not synchronized, or something really nasty happened. Please wait a few minutes and try again. Remember to pass the -v option to freshclam.
It is also possible that you recently had a prolonged network outage and freshclam blacklisted all the mirrors: remove mirrors.dat from the DatabaseDirectory and try again.
If the problem persists, you may need to remove all files in DatabaseDirectory, and then re-run freshclam to pull a new copy of all of them.
Starting from ClamAV 0.9x, whenever your ClamAV engine becomes outdated and the difference between the functionality level required by the CVD and the functionality level supported by your ClamAV engine is more than 3, freshclam will refuse to check for updates more often than 6 times per day.
The reason for this is that there is no use to generate traffic on our mirrors if you cannot take advantage of all the signatures anyway. If you really care about catching as much malware as possible and you want to check for updates more often than 6 times per day, then you should also not run such an old version of ClamAV.
This feature was introduced after our mirror sysadmins complained that really old versions of ClamAV were consuming more than 50% of their bandwidth to download some CVD updates that were almost useless to them (due to lack of support for mdb signatures).
This message does NOT indicate that you are unable to download the latest CVD update! You’ll get this message whenever a new version of ClamAV is released. In order to detect all the latest viruses, it’s not enough to keep your database up to date. You also need to run the latest version of the scanner.
The functionality level of the database determines which scanner engine version is required to use all of its signatures. If you don’t upgrade immediately you will still be able to download the latest CVD updates but the engine won’t be able to use ALL of them.
If you are experiencing this problem, please do the following: Stop the
freshclam daemon if it’s running, delete both
daily.cvd, then restart the
freshclam daemon. Freshclam will then download a new
daily.cvd and will be up-to-date.
Please report all mirror failures or issues on Bugzilla.