ARGUS Sensor

Sensor History

Argus was started by Carter Bullard as a part of his research at Georgia Tech in the early 80's.  GaTech was a network center of excellence.  It maintained possibly the largest X-25 research lab, it built the largest campus ethernet network in the world (at the a time), it was one of the top 5 Usenet nodes in the world (a big deal), and it was a key part of the emerging NSFnet and SURAnet networks.  We were developing / testing TCP/IP stacks for a number of computer vendors and the research group was early in developing Voice over ethernet and Voice over IP technology which ran over the CS ethernet networks, and so simple awareness of what was on the wire was important.

At the time there were only two approaches for network analysis and awareness, interface counters accessed through consoles and then later through SNMP, and wireline awareness through packet capture.  In order to 'understand' how large university networks were being used, SNMP interface statistics didn't provide enough information, and large scale packet capture at 1Mbps was impossible, since disk space was very, very, very expensive.  

Argus was at first developed as an independent network monitor, that could provide near realtime summarized network activity for network debugging.  It was the first technology to use the 5-tuple IP flow spec to classify packet data and to visualize network flow activity.  This quickly moved out of the lab and into the operational network to provide operational support for uptime and network faults, and then into the NSF networks infrastructure, giving the network operators unprecedented views into how GaTech's networks were being used.  It was key to detecting that GaTech was a launch point for attacks on Equifax by the Legion of Doom, and it was operational during the Morris Worm, the most devastating Cyber attack in network history.

When Carter moved to CMU's Software Engineering Institute, as the networking guy at the Computer Emergency Response Team, work started on Argus as a cyber security technology.  We continued to develop Argus as a real-time operational sensor at the SEI, but we also integrated Argus data into the cyber security workflow.  We started to evangelize the idea that network accountability was critically important to network forensics and incident response in the early 1990's, at the IETF, NANOG and to vendors, such as Cisco in 1993.  In 1995 Argus was placed as an open source project by CMU and Carter Bullard, under the GNU Public License, and it has been maintained by Carter since.


Sensor Development

The sensor part of Argus is all about generating bi-directional network flow data.  Within the open source sensor project, we focus on many parts of the sensor development problem; design, implementation, deployment, testing, configuration, maintenance and testing.  But when we talk about sensor development, we try to focus on the technical issues of high performance packet processing; packet header parsing, bi-directional classification, sessionization, feature capture, data formats, and data transport.

The Argus sensor is both an operational real-time software sensor, capable of running at 100Gbps on commercially available commodity platforms, and a  network traffic analytic, that processes packets for analysis and investigation, providing packet classification, sessionization, packet dynamic measurement, aggregation and periodic reporting.  Ported to over 25 platforms, Argus can generate network flow data just about anywhere, providing the same dense network data, no matter where it's deployed.

Design Goals

 Argus is designed based on a few principal goals.

  1. Argus must account for every packet observed in its output, i.e. non-statistical.
  2. Support operations, performance and security analytics.
  3. Extendable through metadata enhancement.

In order to provide comprehensive network flow data, Argus cannot be statistical. When utilities need to know what is going on in a network, it can't get a statistical look. This complete accounting of all the packets observed is an primary goal of Argus and its data, and differentiates it from other flow systems.

Supporting operations, performance and security management analytics means that Argus data need to have the attributes that are needed for these tasks. Reachability indicators for operations management, loss detection for performance measurements, and content for security analytics, are just a few examples.

The world of network security has really advanced in the last 10 years, and Argus has kept pace, providing the richest general network flow data available today.  Its comprehensive (non-statistical) transaction model is designed to support the complete NIST Cyber Security Framework, Identify, Protect, Detect, Respond and Recover.  Advanced comprehensive network flow data, with metadata enhancements, embedded protocol verifications + payload capture provides the information needed to find network evidence of the bad thing, intrusion, exploitation, exfiltration, shadow IT.  Whether the network activity reflects malware attempting to discover nodes in the local network, attempts to break into adjacent systems, stepping stone behavior, Argus data is rich enough to provide the basic information needed to identify and detect bad actor behavior in the network.

Flow Sensor Tech

The argus sensor is a multi-threaded packet processor that relies on native operating system support to process live network packet streams, or to read packets from named pipes or files.  It parses all network headers, until it finds the end-to-end Layer 3 Transport header, and then tracks the transport state until it times out due to an idle state.

Keeping up with new modern encapsulations, such as those in NVO3, GUE, VXLAN are important to keeping argus relevant.  If you're interested in theoretical models of network communications, get involved.

Argus is best used in large distributed deployments.  Helping argus to be free of complex configuration issues, and to support massive scale deployment, is a real challenge.  If you like this type of development, get involved.

100 Gbps


Non-IP Traffic

Endpoint Sensing

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