Engine for capturing, parsing and replaying DNS
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README.md

Engine for capturing, parsing and replaying DNS

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dnsjit is a combination of parts taken from dsc, dnscap, drool, and put together around Lua to create a script-based engine for easy capturing, parsing and statistics gathering of DNS messages while also providing facilities for replaying DNS traffic.

One of the core functionality that dnsjit brings is to tie together C and Lua modules through a receiver/producer interface. This allows creation of custom chains of functionality to meet various requirements. Another core functionality is the ability to parse and process DNS messages even if the messages are non-compliant with the DNS standards.

NOTE current implementation is ALPHA which means functionality are not set and may be changed or removed.

The following Lua module categories exists:

  • dnsjit.core: Core modules for handling things like logging, DNS messages and receiver/receive functionality.
  • dnsjit.lib: Various Lua libraries or C library bindings.
  • dnsjit.input: Input modules used to read DNS messages in various ways.
  • dnsjit.filter: Filter modules to process or manipulate DNS messages.
  • dnsjit.output: Output modules used to display DNS message, export to various formats or replay them against other targets.

See each category's man-page for more information.

Packages

https://dev.dns-oarc.net/packages

Packages for Debian, Ubuntu, EPEL, SLE, openSUSE can be found in the PRE-RELEASE channel. Some distributions are limited to certain architectures because of LuaJIT.

Dependencies

Debian/Ubuntu: apt-get install libluajit-5.1-dev libpcap-dev luajit liblmdb-dev libck-dev libgnutls28-dev

CentOS: yum install luajit-devel libpcap-devel lmdb-devel ck-devel gnutls-devel

FreeBSD: pkg install luajit libpcap lmdb gnutls + manual install of libck

OpenBSD: pkg_add luajit gnutls + manual install of libpcap, liblmdb and libck

Build

git clone https://github.com/DNS-OARC/dnsjit
cd dnsjit
sh autogen.sh
./configure
make

Documentation

Most documentation exists in man-pages and you do not have to install to access them, after building you can do:

man src/dnsjit.1
man src/dnsjit.core.3
man src/dnsjit.lib.3
man src/dnsjit.input.3
man src/dnsjit.filter.3
man src/dnsjit.output.3

Usage

Run a Lua script:

dnsjit file.lua ...

Shebang-style:

#!/usr/bin/env dnsjit
...

Example

Following example display the DNS ID found in queries.

require("dnsjit.core.objects")
local input = require("dnsjit.input.pcap").new()
local layer = require("dnsjit.filter.layer").new()
local dns = require("dnsjit.core.object.dns").new()

input:open_offline(arg[2])
layer:producer(input)
local producer, ctx = layer:produce()

while true do
    local object = producer(ctx)
    if object == nil then break end
    if object:type() == "payload" then
        dns.obj_prev = object
        if dns:parse_header() == 0 then
            print(dns.id)
        end
    end
end

See more examples in the examples directory.

Copyright

Copyright (c) 2018, OARC, Inc.

All rights reserved.

This file is part of dnsjit.

dnsjit is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

dnsjit is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with dnsjit.  If not, see <http://www.gnu.org/licenses/>.