
Snort 3.0 is an updated version of the Snort Intrusion Prevention System (IPS) which features a new
design that provides a superset of Snort 2.X functionality with better efficacy, performance,
scalability, usability, and extensibility.  Some of the key features of Snort 3.0 are:

* Support multiple packet processing threads
* Use a shared configuration and attribute table
* Autodetect services for portless configuration
* Modular design
* Plugin framework with over 200 plugins
* More scalable memory profile
* LuaJIT configuration, loggers, and rule options
* Hyperscan support
* Rewritten TCP handling
* New rule parser and syntax
* Service rules like alert http
* Rule "sticky" buffers
* Way better SO rules
* New HTTP inspector
* New performance monitor
* New time and space profiling
* New latency monitoring and enforcement
* Inspection Events
* Autogenerate reference documentation

=== Efficacy

* Detects and blocks all but 10 HTTP Evader tests (see https://noxxi.de/research/http-evader.html).

* Autodetection of services reduces misses due to incorrect or out of date port configurations and
  improves detection on unexpected command and control channels.

=== Performance

* Vastly improved throughput over Snort 2 for deep flow inspection.

* Many more fast pattern buffers means fewer non-fast pattern rules.

* Hyperscan is used for faster fast patterns, content literals and (optionally) compatible PCRE
  during signature evaluation, and various searches done by inspectors.

* sd_pattern rules have normal fast patterns, don't require extra searches.

* The snort3_demo repo has a performance suite that can be used to compare Snort 2 and Snort 3.

* The DAQ 3 interface facilitates leveraging your data plane for maximum throughput including
  checksum offload and acquisition of a vector of packets.

* Snort 3 is not run-to-completion, making it possible to detain packets for lookaside acceleration
  and other new features.

=== Scalability

* Much easier to leverage multiple cores.

* All packet threads share configuration and rule engine which frees up much more memory for packet
  processing.

=== Usability

* Sticky buffers make it easier to write correct rules.

* Autodetection eliminates much port configuration maintenance.

* Service-based detection doesn't preclude port-based detection.

* Builtin defaults and policy tweaks make effective tuning much simpler.

* Command line help and generated reference documentation make it easy to get the correct
  configuration details.

* A trace mechanism is provided to make it easy to see how packets are processed.

* Build a scaled down image and configure for smaller systems such as IoT devices.

* The snort2lua utility (described later) makes it easy to convert your local rules.

* Extensive peg counts capture the important events and actions to provide more detailed insight
  into your deployment.

=== Extensibility

* Several plugin types are defined and over 220 plugins are available.

* Inspection events make collaboration among plugins possible without framework updates.

* All plugins, including SO rules, can be mixed in the same library.

* A command line shell is available for reloads and other operations.

* The snort3_extra repo has examples to each plugin type to help you get started.

* Easy to add SO rules for 0-day attacks.

