Freshclam and HTTP Proxy#
Similarly to the scenario described in Section Carbonio CE and HTTP Proxy,
freshclam can not download the antivirus signatures if
Carbonio CE is placed behind a proxy. The solution is to put the proxy
information in the freshclam configuration template,
which is /opt/zextras/conf/freshclam.conf.in.
Log in to the Node where the MTA AV/AS Role is installed and edit the file, by adding at the bottom the lines:
HTTPProxyServer proxy.example.com
HTTPProxyPort 8080
As the zextras user, execute
zextras$ zmclamdctl restart
To verify that the new configuration is correct and the HTTP proxy is being used, check the log file
zextras$ tail -f /opt/zextras/log/freshclam.log
In the output you should find some lines similar to the following:
ClamAV update process started at Thu Mar 13 14:01:58 2025
Trying to retrieve CVD header from https://database.clamav.net/daily.cvd
OK
main database available for download (remote version: xx)
Testing database: '/opt/zextras/data/clamav/db/tmp.03d9f579e4/clamav-f220b006e75bbf945b40dd0f5b8a2f29.tmp-main.cvd' ...
Database test passed.
main.cvd updated (version: 62, sigs: 6647427, f-level: 90, builder: sigmgr)
Trying to retrieve CVD header from https://database.clamav.net/bytecode.cvd
OK
If you have modified freshclam's configuration template
/opt/zextras/conf/freshclam.conf.in , you will likely need
to edit it again after an upgrade, because upgrades often overwrite
configuration templates. Since Carbonio CE regenerates
freshclam.conf from the template file, when Carbonio CE or
ClamAV updates, the template may be reset to default or overwritten
with a new version, losing any changes you made to it. In this
case, any custom modifications would be lost.
To make sure changes are preserved after an upgrade, create a backup of the template file
zextras$ cp /opt/zextras/conf/freshclam.conf.in /opt/zextras/conf/freshclam.conf.in.backup
After the upgrade, compare and restore changes
zextras$ diff /opt/zextras/conf/freshclam.conf.in.backup /opt/zextras/conf/freshclam.conf.in
If the output is empty, there is no difference between the new template and the backup, so freshclam will keep on working without issues. If you see any difference, you might want to restore the proxy settings, by following this procedure from the beginning or copying your backup file on the new template.
zextras$ cp /opt/zextras/conf/freshclam.conf.in.backup /opt/zextras/conf/freshclam.conf.in