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Automated Parser Generation for High-Speed NIDS PowerPoint PPT Presentation


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Hongyu Gao Clint Sbisa. Automated Parser Generation for High-Speed NIDS. Motivation. Processing speed is crucial concern for NIDS/NIPS Limited by rate of parsing packets Inefficient parsing leads to slow speeds and bottlenecks. Current Solutions. Binpac Declarative language and compiler

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Automated Parser Generation for High-Speed NIDS

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Hongyu Gao

Clint Sbisa

Automated Parser Generation for High-Speed NIDS


Motivation

  • Processing speed is crucial concern for NIDS/NIPS

  • Limited by rate of parsing packets

  • Inefficient parsing leads to slow speeds and bottlenecks


Current Solutions

  • Binpac

    • Declarative language and compiler

    • Designed to simplify task of constructing complex protocol parsers

    • Constructs a full parsing tree


Current Solutions

  • Netshield

    • Integrate high-speed protocol parser to provide fast parsing speed

    • Parsers are manually written, which is tedious work and error-prone


Proposed Solution

  • A protocol parser generator

  • Read the protocol specification

  • Output the parser for the specific protocol

  • The parser is aware of matching

  • The parser focuses on the fields needed by matching and skip unnecessary fields


Proposed Solutions


Design Principles

  • The parsing process should avoid recursive calls

    • Parse trees are not used in parsing phase

  • Skip unneeded information

    • After parsing one field, the parser should be able to quickly jump to the next necessary field


Detailed design

  • The parser consists of three parts

  • A pair of buffer pointers

  • A field table ( key data structure)

  • A table pointer


Detailed design on field table


Detailed Design on Parser


Implementation

  • Basic approach:

    • Fixed driver

    • Fixed data structure

    • Protocol-specific table content


Related files


How to realize the system

  • Determine the size of field table

    • Start with one root node in protocol parse tree

    • Iteratively substitute complex field with multiple simpler fields

  • Determine the FieldLength function

    • Retrieve the information from Type class

    • Type::attr_length_expr_,

    • Type::attr_oneline_,

    • etc.


How to realize the system

Determine the GarbageLength function

Before compression, GarbageLength returns “0” for every field

Compress the table

Look forward for consequent fields

Merge the length of unused fields into garbage fields of the field that precedes them


Snapshot for generated code


Snapshot for generated code, cont’d


Snapshot for generated code, cont’d


Demo


Questions? Suggestions?


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