Thursday, December 11, 2014

Project Snort++, a.k.a. Snort 3.0


The Snort++ project has been hard at work for a while now and we are finally ready to release the first alpha of the next generation Snort IPS (Intrusion Prevention System). This post will show you what Snort++ has to offer and guide you through the steps from download to demo. If you are unfamiliar with Snort you should take a look at the Snort documentation first. We will cover the following topics:
  • Overview
  • Dependencies
  • Download
  • Build Snort
  • Run Snort
  • Documentation
  • Squeal


This first alpha release is based on early Snort 2.9.6 and excludes all but one of Snort's dynamic preprocessors (ftp_telnet). Work is underway to port that functionality and sync with 2.9.7; those updates will be rolled out as they become available.

    Project = Snort++
    Binary = snort
    Version = 3.0.0-a1

Here are some key features in this alpha release:
  • Support multiple packet processing threads
  • Use a shared configuration and attribute table
  • Use a simple, scriptable configuration
  • Make key components pluggable
  • Autodetect services for portless configuration
  • Support sticky buffers in rules
  • Autogenerate reference documentation
  • Provide better cross platform support
Additional features on the roadmap include:
  • Use a shared network map
  • Support pipelining of packet processing
  • Support hardware offload and data plane integration
  • Rewrite critical modules like TCP reassembly and HTTP inspection
  • Support proxy mode
  • Facilitate component testing
  • Simplify memory management
  • Provide all of Snort's functionality


If you already build Snort, you may have everything you need. If not, grab the latest:
  • autotools or cmake to build from source
  • g++ >= 4.8 or other C++11 compiler
  • daq from for packet IO
  • dnet from for network utility functions
  • LuaJIT from for configuration and scripting
  • pcap from for tcpdump style logging
  • pcre from for regular expression pattern matching
  • zlib from for decompression
  • pkgconfig from to build the example plugins


There are two source tarballs, once for autotools and one for cmake:


First do these setup steps:

    export my_path=/path/to/snorty
    tar zxf snort-tarball
    cd snort-3.0.0*

Then do one of the following:
  • To build with autotools, simply do the usual from the top level directory:
    ./configure --prefix=$my_path
    make -j 8 install
  • To build with cmake and make, run It will automatically create and populate a new subdirectory named 'build'.
    ./ --prefix=$my_path
    cd build
    make -j 8 install

  • If you can do src/snort -V you built successfully.
  • If you are familiar with cmake, you can run cmake/ccmake instead of
  • cmake --help will list any available generators, such as Xcode. Feel free to use one, however help with those will be provided in a later post.


First set up the environment:

    export LUA_PATH=$my_path/include/snort/lua/\?.lua\;\;
    export SNORT_LUA_PATH=$my_path/etc/snort

Then give it a go:
  • Snort++ provides lots of help from the command line. Here are some examples:
    $my_path/bin/snort --help
    $my_path/bin/snort --help-module suppress
    $my_path/bin/snort --help-config | grep thread
  • Examine and dump a pcap:
    $my_path/bin/snort -r pcap
    $my_path/bin/snort -K text -d -e -q -r pcap
  • Verify a config, with or w/o rules:
    $my_path/bin/snort -c $my_path/etc/snort/snort.lua
    $my_path/bin/snort -c $my_path/etc/snort/snort.lua -R $my_path/etc/snort/sample.rules
  • Run IDS mode. In the following, replace a.pcap with your favorite. pcaps/ is a directory with one or more *.pcap files:
    $my_path/bin/snort -c $my_path/etc/snort/snort.lua -R $my_path/etc/snort/sample.rules \
        -r a.pcap -A alert_test -n 100000
  • Let's suppress 1:2123. We could edit the conf or just do this:
    $my_path/bin/snort -c $my_path/etc/snort/snort.lua -R $my_path/etc/snort/sample.rules \
        -r a.pcap -A alert_test -n 100000 --lua "suppress = { { gid = 1, sid = 2123 } }"
  • Go whole hog on a directory with multiple packet threads:
    $my_path/bin/snort -c $my_path/etc/snort/snort.lua -R $my_path/etc/snort/sample.rules \
        --pcap-filter \*.pcap --pcap-dir pcaps/ -A alert_fast --max-packet-threads 8


Take a look at the manual, parts of which are generated by the code so it stays up to date:


It does not yet have much on the how and why, but it does have all the currently available configuration, etc. Some key changes to rules:
  • you must use comma separated content sub options like this: content:"foo", nocase;
  • buffer selectors must appear before the content and remain in effect until changed
  • pcre buffer selectors were deleted
  • check the manual for more on Snort++ vs Snort
  • check the manual reference section to understand how parameters are defined, etc.
It also covers new features not demonstrated here:
  • snort2lua, a tool to convert Snort 2.X conf and rules to the new form
  • a new HTTP inspector, new_http_inspect - incomplete but off to a good start
  • a binder, for mapping configuration to traffic
  • a wizard for port-independent configuration
  • improved rule parsing - arbitrary whitespace, C style comments, #begin/#end comments
  • local and remote command line shell


We hope you are as excited about Snort++ as we are. Although a lot of work remains, we wanted to give you a chance to try it out and let us know what you think on the snort-users list. In the meantime, we'll keep our snout to the grindstone.


  1. After ( make -j 8 install ) I get this error can you tell me plz how to solve it : here's the error :

    make[2]: *** [src/network_inspectors/normalize/CMakeFiles/normalize.dir/] Error 1
    make[1]: *** [src/network_inspectors/normalize/CMakeFiles/normalize.dir/all] Error 2
    make[1]: *** Waiting for unfinished jobs....
    Preprocessed source stored into /tmp/ccmkbWp4.out file, please attach this to your bugreport.
    make[2]: *** [src/stream/tcp/CMakeFiles/stream_tcp.dir/] Error 1
    make[1]: *** [src/stream/tcp/CMakeFiles/stream_tcp.dir/all] Error 2
    make: *** [all] Error 2

    1. I suggest that you address your question to the appropriate Snort mailing list found here:

      While I try, I can't get to everyone's email personally and this allows us to leverage everyone on the team as well as the whole open source community.

      Thank you.

  2. easy install using custom vmware image here: