Snort++
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
OVERVIEW
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
- 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
DEPENDENCIES
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 http://www.snort.org for packet IO
- dnet from http://code.google.com/p/libdnet/ for network utility functions
- LuaJIT from http://luajit.org for configuration and scripting
- pcap from http://www.tcpdump.org for tcpdump style logging
- pcre from http://www.pcre.org for regular expression pattern matching
- zlib from http://www.zlib.net for decompression
- pkgconfig from http://www.freedesktop.org to build the example plugins
DOWNLOAD
There are two source tarballs, once for autotools and one for cmake:snort-3.0.0-a1-130-auto.tar.gz snort-3.0.0-a1-130-cmake.tar.gz
BUILD SNORT
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=$my_path
make -j 8 install
- To build with cmake and make, run configure_cmake.sh. It will automatically create and populate a new subdirectory named 'build'.
./configure_cmake.sh --prefix=$my_path
cd build
make -j 8 install
Note:
- If you can do src/snort -V you built successfully.
- If you are familiar with cmake, you can run cmake/ccmake instead of configure_cmake.sh.
- 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.
RUN SNORT
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
DOCUMENTATION
Take a look at the manual, parts of which are generated by the code so it stays up to date: $my_path/share/doc/snort/snort_manual.pdf
$my_path/share/doc/snort/snort_manual.html
$my_path/share/doc/snort/snort_manual/index.html
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.
- 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