User guide

Using VStream Antivirus
Chapter 15: Using Antivirus and Antispam Filtering 511
Configuring the VStream Antivirus Policy
VStream Antivirus includes a flexible mechanism that allows the user to define exactly
which traffic should be scanned, by specifying the protocol, ports, and source and
destination IP addresses.
VStream Antivirus processes policy rules in the order they appear in the Antivirus Policy
table, so that rule 1 is applied before rule 2, and so on. This enables you to define
exceptions to rules, by placing the exceptions higher up in the Rules table.
For example, if you want to scan all outgoing SMTP traffic, except traffic from a specific
IP address, you can create a rule scanning all outgoing SMTP traffic and move the rule
down in the Antivirus Policy table. Then create a rule passing SMTP traffic from the
desired IP address and move this rule to a higher location in the Antivirus Policy table than
the first rule. In the figure below, the general rule is rule number 2, and the exception is
rule number 1.