User Manual Part 2

Using VStream Antivirus
Chapter 15: Using Antivirus and Antispam Filtering 485
In this field… Do this…
Archive File Handling
Maximum Nesting Level Type the maximum number of nested content levels that
VStream Antivirus should scan.
Setting a higher number increases security. Setting a lower
number prevents attackers from overloading the gateway by
sending extremely nested archive files.
The default value is 5 levels.
Maximum Compression
Ratio 1:x
Fill in the field to complete the maximum compression ratio of
files that VStream Antivirus should scan.
For example, to specify a 1:80 maximum compression ratio, type
80.
Setting a higher number allows the scanning of highly
compressed files, but creates a potential for highly compressible
files to create a heavy load on the appliance. Setting a lower
number prevents attackers from overloading the gateway by
sending extremely compressible files.
The default value is 100.
When archived file
exceeds limit or extraction
fails
Specify how VStream Antivirus should handle files that exceed
the Maximum nesting level or the Maximum compression ratio, and
files for which scanning fails. Select one of the following:
• Pass file without scanning. Scan only the number of
levels specified, and skip the scanning of more deeply
nested archives. Furthermore, skip scanning highly
compressible files, and skip scanning archives that
cannot be extracted because they are corrupt. This is
the default.
• Block file. Block the file.