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A small library for unified2 parsing in node.js. Unified2 is a common output format for network intrusion detection devices such as Snort + Suricata.

See Sourcefire's documentation for the unified2 protocol:


$ npm install unified2 



var unified2 = require('unified2');
parser = new unified2unified2.Parser('unified2.alert.14560142132', { offset: 0 });
parser.on('data', function(data) {
  // event data... 
parser.on('error', function(error) {
  // error 
parser.on('eof', function() {
  // triggered when an EOF (no data is received).  Useful to save a bookmark 
  // when you are running in tail mode (see below). 
parser.on('rollover', function() {
  // triggered when a rollover is detected (the file shrinks in size) 
parser.on('end', function(data) {
  // triggered when parser ends (e.g., out of data) 

Tailing a file

It is often useful to wait for more data as the file is being written, e.g. by a Snort sensor.

Simply pass tail: true in the options for the parser to wait for more logs, e.g.:

var unified2 = require('unified2');
parser = new unified2.Parser('unified2.alert.14560142132', { offset: 0, tail: true });

To stop the parser, you can do parser.stop() which will trigger an end event.


To read the current bookmark, you can use parser.last_read_position, which is the offset after the last read unified2 event. Useful after a 'eof' event or 'end' event if you wish to resume parsing again later, you can pass this into the offset: <value> parameter in the Parser constructor.

Debug logging

pass in DEBUG=unified2 as an environment variable to turn on debug logging.

Is it fast? This is javascript after all.

In tests, parsing happens at about ~7000k/events per second. Obviously, this slows down as you add processing and IO.

Here's reading ~4.6 MB and writing parsed objects (~34MB) to stdout.

unified2 (master*) $ time node tests/test.js > /tmp/test.js.output                                                                                                                                                                ~/src/unified2
node tests/test.js > /tmp/test  11.67s user 0.38s system 100% cpu 11.977 total


Right now, this is just a bare bones parser. E.g., the pcaps and extra data are not correlated with the ids event messages. This is intentional.

Please refer to Pigsty ( for a more complete unified2 parser and plugin framework for handling the output.

Bug Reporting

Please use Github or email


Copyright (C) 2013 Threat Stack, Inc (

This program 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.

This program 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 this program. If not, see