Kerio Tech Firewall6 User Manual
Page 180
Chapter 13
Antivirus control
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Use the Options button to set advanced parameters for the selected antivirus. Dialogs for in-
dividual antiviruses differ (some antivirus programs may not require any additional settings).
For detailed information about installation and configuration of individual antivirus programs,
refer to
.
Click Apply to test the selected antivirus. If the test is passed successfully, the antivirus will
be used from the moment on. If not, an error is reported and no antivirus will be set. Detailed
information about the failure will be reported in the Error log (see chapter
).
Antivirus settings
Check items in the Settings section of the Antivirus tab to enable antivirus check for individual
application protocols. By default, antivirus check is enabled for all supported modules.
In Settings, maximum size of files to be scanned for viruses at the firewall can be set. Scanning
of large files are demanding for time, the processor and free disk space, which might affect
the firewall’s functionality dramatically. It might happen that the connection over which the
file is transferred is interrupted when the time limit is exceeded.
The optimal value of the file size depends on particular conditions (the server’s performance,
load on the network, type of the data transmitted, antivirus type, etc.). Caution! We strongly
discourage administrators from changing the default value for file size limit. In any case, do
not set the value to more than 4 MB.
Figure 13.5
Selecting application protocols to be scanned and setting file size limits
Parameters for HTTP and FTP scanning can be set in the HTTP and FTP scanning (refer to
chapter
), while SMTP and POP3 scanning can be configured in the Email scanning tab (see
chapter
Warning
1.
In case of SMTP protocol, only incoming traffic is checked (i.e. traffic from the Internet to
the local network — incoming email at the local SMTP server). Checks of outgoing SMTP
traffic (from the local network to the Internet) might cause problems with temporarily
undeliverable email — for example in cases where the destination SMTP server uses so
called greylisting.
To perform smooth checks of outgoing traffic, define a corresponding traffic rule using
the SMTP protocol inspector. Such rule may be useful for example if clients in the local