You know the daily.cvd file is now larger than the main.cvd file, so you are burning up a lot of bandwidth if your world-facing ClamAV mirror is ignoring cdiff files. If it is using freshclam then it is using cdiffs and merging them as part of the process of mirroring. In that case your clients won't see the cdiff files which is perfectly acceptable. I used to use a proxy when many systems were co-located and it was very effective and was also being used for other purposes. Life is much simpler now that I'm retired.


On 12/11/18 11:45 AM, Paul Kosinski wrote:
Ever since we set up a local mirror on our LAN, we have not been using
cdiffs. The reason for this is that I followed the procedure outlined
on the ClamAV website (about 2/3 down the page) at:

where it says:

[Q] I’m running ClamAV on a lot of clients on my local network.  Can I serve 
the cvd files from a local server
     so that each client doesn’t have to download them from your servers?
[A] 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 machine1.mylan) Let freshclam download the *.cvd files from to the webserver’s DocumentRoot. Finally, change freshclam.conf on your clients so that it includes: DatabaseMirror machine1.mylan ScriptedUpdates off 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!

Since I didn't want to set up a proxy server for this purpose, I used
the 2nd solution (and a very trivial web server). Thus, cvd files only.

P.S. I am now thinking about trying the BOS vs IAD test for cdiff
files. But, even if cdiff files always work without any delays, doesn't
"scripted update" on occasion have to back off to downloading full cvds?

P.P.S. Thanks for the curl help!

On Mon, 10 Dec 2018 20:34:45 -0800
Dennis Peterson <> wrote:

You were using curl (I did remember that after I posted as I'd helped
you sort out curl options to do what you wanted) to explore what was
available on the servers compared to what was on the DNS TXT record,
and that was outside process. It also ignored cdiff files that may
have been available in a version that matched the TXT record. The
purpose of the cdiff files is to cut down on bandwidth.


On 12/10/18 6:34 PM, Paul Kosinski wrote:
We ARE using freshclam to perform the actual update. And always have

We've only been using curl (not wget, if that matters) to pull the
first few bytes of the cvd to see if its version number matches
what the DNS TXT query said.

We do this because, after the conversion to Cloudflare, we were
getting lots of FAILURES where *freshclam* said things were out of
sync (and eventually disabled all the mirrors).

And we have recently seen that our Web server sometimes can get the
new updates (from IAD) *hours* before our main LAN does (from BOS).

P.S. It's been quite frustrating getting some replies seemingly
based on assumptions that we are doing things we shouldn't, when we
aren't in fact doing those things. (Like not using freshclam.)

On Mon, 10 Dec 2018 16:46:42 -0800
Dennis Peterson <> wrote:

Exactly right. We can't be blaming the ClamAV process when we don't
use the ClamAV process. People that don't use freshclam should have
no expectation of high reliability. In fact any expectations are
baseless when the wrong tools are employed.


On 12/9/18 5:44 AM, Joel Esler (jesler) wrote:
As it should be.  No one should be downloading the daily and main,
(although thousands are), cdiffs were created for a reason.

Sent from my  iPhone

On Dec 9, 2018, at 06:58, Eric Tykwinski <>

   From back in archives, I think he’s using wget to just pull the
files, but freshclam would just pull the cdiffs and keep you up
to date on the next check.
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