FlowScanA Network Traffic Reporting and
Visualization Tool
Dave Plonka
Presentation Overview
Introduction FlowScan's Functionality Hardware & Software Components
Sample Graphs Short & Long Term Analyses, Events Graphs by Autonomous Systems, Top ASNs SubNetIO graphs
References
FlowScanA Network Traffic Reporting and
Visualization Tool
FlowScan is a software package for open systems that is freely available under the terms of the GNU General Public License.
FlowScan analyzes and reports on flow data exported by Internet Protocol routers.
FlowScan produces graph images which provide a continuous, near real-time view of the network traffic across a network's border.
Development since December 1998. Beta release in September 1999. Released March 2000.
Background on Flows & Cisco NetFlow
The notion of flow profiling was introduced by the research community
Today, for performance and accounting reasons, flow profiling is built into some networking devices
Not yet standards-based
FlowScan utilizes flows defined and exported by Cisco's NetFlow feature. Essentially using the definition introduced by [ClaffyPB].
By this definition, an IP flow is a unidirectional series of IP packets of a given protocol, traveling between a source and destination, within a certain period of time.
Sample Flowsncftp GET session
Background on Flows & Cisco NetFlow
Diagram by Daniel W. McRobb, from the cflowd configuration documentation, 1998-1999.
FlowScan'sFunctionality
FlowScan examines each flow and maintains counters based upon that flow's classification
FlowScan periodically reports what it finds into databases. Each database contains packet, byte, and flow counters
Counters are maintained based on these flow attributes:
IP protocol such as ICMP, TCP, and UDP
well-known service or application such as ftp-data, ftp, smtp, nntp, http, RealMedia, Quake, and Napster
the class A, B, C network, or CIDR block in which a "local" IP address resides
the AS (Autonomous System) pair between which the represented traffic was exchanged
FlowScan's Functionality
FlowScan HardwareComponents
Works with most Cisco routers
Compatibility with Juniper's routers and RiverStone's Switch Router (formerly Cabletron's SSR) is being developed
Most FlowScan systems are Sun SPARC Solaris machines or Intel GNU/Linux or BSD machines
The fastest FlowScan machines appear to be multi-processor Intel PIII machines
GIF or PNG image files suitable for any web server, we use Apache
FlowScan HardwareComponents
FlowScan SoftwareComponents
Perl
Perl modules
Patched cflowd
RRDtool
Unix or GNU/Linux Cron Make
Flowscan script
CampusIO report
SubNetIO report
Software
Short Term Analysis
Graphs over a short, recent time frame are based upon five-minute intervals.
Network abuse, such as flood-based Denial of Service attacks, are easily visible as "stalagmites" and "stalactites". These would be hidden in coarser-grained long-term graphs
This Example:
Flood of outbound 40-byte TCP RST reply packets
Flood of inbound 40-byte TCP ACK packets
Resulted in as much as 10,000 flows per second
Short Term Analysis
Short Term AnalysisBits, Packets, Flows Graphs
48 hours, 4-6 Nov 2000
2000/11/05 ~0200 -> ~1000 Apparently peering w/Abilene was down. (This was due to changes at AADS)
2000/11/05 ~0415 -> ~1100 outbound flood of UDP packets ~10,000 packets per second
2000/11/05 ~0800, ~0830 inbound flood of 1500 byte ICMP ECHO and ECHOREPLY packets destined for a campus dial-up user. This amounted to as much as 25 Mb/s.
2000/11/05 ~1400 -> ? Apparently peering w/Abilene was down again. StarTAP too. (More problems at AADS)
2000/11/06 ~0730 AADS got things back together connectivity to Abilene and StarTAP restored.
CampusIOUniversity of Wisconsin - Parkside
10-11 Nov 2000
Graph by Steven Premeau <[email protected]>, 2000.
Long Term Analysis
Daily average graphs aid capacity planning and traffic shaping efforts.
This example:
Graph produced 2000/09/21 over past 550 days
academic calendar dramatically influences the traffic levels, but only to and from ResNet.
increase in outbound ftp traffic from the Computer Sciences department within the past year.
outbound traffic has consistently exceeded our inbound traffic level, the discrepancy between the two appears to be increasing.
CampusIOLong Term Analysis
550 days prior to 21 Sep 2000
CampusIO NapsterDaily Averages
March Through September 2000
Note that these are daily averages, five minute peak Napster traffic would be higher
Note two "horns" or spikes in late March and Septemember. These represent some of the highest outbound daily averages observed and will be explored in the subsequent slides.
CampusIO NapsterDaily Averages
March Through September 2000
CampusIO EventsRedHat 6.2 Release
C. Wednesday 29 Mar 2000
Spent an hour or two investigating increased CS traffic before coming in that morning
Found traffic to be TCP on ports >1024, host addresses indicated that it was likely to be PASV mode ftp data
Jump was from ~5Mb/s to ~30Mb/s
David Parter of CS informed me that their RedHat mirror was made active about that time
CampusIO EventsRedHat 6.2 Release
c. Wednesday 29 Mar 2000
CampusIO EventsRedHat 7 Release
"Black" Monday, 25 Sep 2000
PASV mode ftp detection built-into CampusIO by this time
Jump from 5-10Mb/s to 50-60Mb/s for CS; another RedHat mirror is in the "blue", Student Information Technology
Notice flat-topping in daily peaks. This is due to the hitting capacity of WiscNet's commodity internet connectivity to Chicago
at capacity of upstream links for nearly entire days
CampusIO EventsRedHat 7 Release
"Black" Monday, 25 Sep 2000
CampusIO Events"All in 2 day's work"Monday & Tuesday, 23-24 Oct 2000
Note arrow of time and events occur left to right:
2000/10/03 0500 peer router upgrade, RSP4 -> RSP8, OC3 -> OC12
2000/10/03 1525 campus to peer cutover from OC3 to OC12
2000/10/03 1915 experimenting with rate-limits
2000/10/04 1100 napster.com outage?
2000/10/04 1615 48-byte TCP inbound DoS flood
2000/10/04 1830 ResNet -> world rate-limit applied
2000/10/04 2100 40-byte TCP SYN outbound DoS flood
CampusIO Events"All in 2 day's work"Monday & Tuesday, 23-24 Oct 2000
CampusIO Events"All in 2 day's work"Monday & Tuesday, 23-24 Oct 2000
A method to visualize "events" and correlate real-world incidents with automated measurement
Working on a generalized approach for instrumenting the Internet to provide this sort of info to sites and researchers
CampusIO Events"All in 2 day's work"Monday & Tuesday, 23-24 Oct 2000
CampusIO ASNsUW-Madison Peers
There is the need in large networks to determine the amount of traffic that each other Autonomous System (AS) sources, sinks, or carries for your institution
These information is used to make informed peering and provisioning decisions
UW-Madison peers with many others, most of our traffic is passed to WiscNet and Abilene
CampusIO ASNsUW-Madison Peers
Wednesday & Thursday, 1-2 Nov 2000
CampusIO ASNsTop Origin ASNs
CampusIO ASNsTop "Path" ASNs
SubNetIO Report
SubNetIO is another "canned" FlowScan report
It is derived from CampusIO; It reports traffic to and from campus done by individual subnets
These examples:
WiscWorld 33.6K and 56K bps dial pool traffic; note inbound DoS attack to at about 3PM
DoIT DSL service rivals the amount of traffic with only a fraction of the number of users; graphs is more erratic because of the smaller population of users
SubNetIOWednesday & Thursday, 1-2 Nov 2000
FlowScanCredits & Thanks
Daniel McRobb and CAIDA for cflowd
Tobi Oetiker and CAIDA for RRDtool
Perl authors and developers for perl and CPAN
Free Software Foundation for GNU
UW-Madison DoIT's Network Operations and Network Engineering Technology groups for mentoring and support
FlowScanA Network Traffic Reporting and
Visualization Tool
http://net.doit.wisc.edu
/~plonka/FlowScan/