User's Manual Part 4

Page 80 SonicWALL SonicOS Standard Administrator’s Guide
1. Pattern Definition Language Interpreter uses signatures that can be written to detect and prevent
against known and unknown protocols, applications and exploits.
2. TCP packets arriving out-of-order are reassembled by the Deep Packet Inspection framework.
3. Deep Packet Inspection engine preprocessing involves normalization of the packet’s payload. For
example, a HTTP request may be URL encoded and thus the request is URL decoded in order to
perform correct pattern matching on the payload.
4. Deep Packet Inspection engine postprocessors perform actions which may either simply pass the
packet without modification, or could drop a packet or could even reset a TCP connection.
5. SonicWALL’s Deep Packet Inspection framework supports complete signature matching across the
TCP fragments without performing any reassembly (unless the packets are out of order). This results
in more efficient use of processor and memory for greater performance.
SonicWALL IPS Terminology
• Stateful Packet Inspection - looking at the header of the packet to control access based on port,
protocol, and IP address.
• Deep Packet Inspection - looking at the data portion of the packet. Enables the firewall to investigate
farther into the protocol to examine information at the application layer and defend against attacks
targeting application vulnerabilities.
• Intrusion Detection - a process of identifying and flagging malicious activity aimed at information
technology.
• False Positive - a falsely identified attack traffic pattern.
• Intrusion Prevention - finding anomalies and malicious activity in traffic and reacting to it.
• Snort - an open source network intrusion detection system. SonicWALL IPS includes open-source
Snort signatures, as well as signatures from other signature databases, and SonicWALL created
signatures. SonicWALL does not use the Snort engine.
• Signature - code written to detect and prevent intrusions, worms, application exploits, and Peer-to-
Peer and Instant Messaging traffic.