Configuring protocol decoders
The FortiGate Intrusion Protection system uses protocol decoders to identify the abnormal traffic patterns that do not meet the protocol requirements and standards. For example, the HTTP decoder monitors traffic to identify any HTTP packets that do not meet the HTTP protocol standards.
To change the ports a decoder examines, you must use the CLI. In this example, the ports examined by the DNS decoder are changed from the default 53 to 100, 200, and 300.
config ips decoder dns_decoder
set port_list "100,200,300"
end
You cannot assign specific ports to decoders that are set to auto by default. These decoders can detect their traffic on any port. Specifying individual ports is not necessary.