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rfc:fyi:fyi33

Network Working Group S. Parker Request for Comments: 2398 C. Schmechel FYI: 33 Sun Microsystems, Inc. Category: Informational August 1998

              Some Testing Tools for TCP Implementors

Status of this Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

Copyright Notice

 Copyright (C) The Internet Society (1998).  All Rights Reserved.

1. Introduction

 Available tools for testing TCP implementations are catalogued by
 this memo.  Hopefully disseminating this information will encourage
 those responsible for building and maintaining TCP to make the best
 use of available tests.  The type of testing the tool provides, the
 type of tests it is capable of doing, and its availability is
 enumerated.  This document lists only tools which can evaluate one or
 more TCP implementations, or which can privde some specific results
 which describe or evaluate the TCP being tested. A number of these
 tools produce time-sequence plots, see
 Tim Shepard's thesis [She91] for a general discussion of these plots.
 Each tools is defined as follows:

Name

 The name associated with the testing tool.

Category

 One or more categories of tests which the tools are capable of
 providing.  Categories used are: functional correctness, performance,
 stress.  Functional correctness tests how stringent a TCP
 implementation is to the RFC specifications.  Performance tests how

Parker & Schmechel Informational [Page 1] RFC 2398 Some Testing Tools for TCP Implementors August 1998

 quickly a TCP implementation can send and receive data, etc.  Stress
 tests how a TCP implementation is effected under high load
 conditions.

Description

 A description of the tools construction, and the implementation
 methodology of the tests.

Automation

 What steps are required to complete the test?  What human
 intervention is required?

Availability

 How do you retrieve this tool and get more information about it?

Required Environment

 Compilers, OS version, etc. required to build and/or run the
 associated tool.

References

 A list of publications relating to the tool, if any.

2. Tools

2.1. Dbs

Author

 Yukio Murayama

Category

 Performance / Stress

Description

 Dbs is a tool which allows multiple data transfers to be coordinated,
 and the resulting TCP behavior to be reviewed.  Results are presented
 as ASCII log files.

Automation

 Command of execution is driven by a script file.

Parker & Schmechel Informational [Page 2] RFC 2398 Some Testing Tools for TCP Implementors August 1998

Availability

 See http://www.ai3.net/products/dbs for details of precise OS
 versions supported, and for download of the source code.  Current
 implementation supports BSDI BSD/OS, Linux, mkLinux, SunOS, IRIX,
 Ultrix, NEWS OS, HP-UX. Other environments are likely easy to add.

Required Environment

 C language compiler, UNIX-style socket API support.

2.2. Dummynet

Author

 Luigi Rizzo

Category

 Functional Correctness / Performance

Description

 Dummynet is a tool which simulates the presence of finite size
 queues, bandwidth limitations, and communication delays.  Dummynet
 inserts between two layers of the protocol stack (in the current
 implementation between TCP and IP), simulating the above effects in
 an operational system.  This way experiments can be done using real
 protocol implementations and real applications, even running on the
 same host (dummynet also intercepts communications on the loopback
 interface).  Reconfiguration of dummynet parameters (delay, queue
 size, bandwidth) can be done on the fly by using a sysctl call. The
 overhead of dummynet is extremely low.

Automation

 Requires merging diff files with kernel source code.  Command-line
 driven through the sysctl command to modify kernel variables.

Availability

 See http://www.iet.unipi.it/~luigi/research.html or e-mail Luigi
 Rizzo (l.rizzo@iet.unipi.it).  Source code is available for FreeBSD
 2.1 and FreeBSD 2.2 (easily adaptable to other BSD-derived systems).

Required Environment

 C language compiler, BSD-derived system, kernel source code.

References

 [Riz97]

Parker & Schmechel Informational [Page 3] RFC 2398 Some Testing Tools for TCP Implementors August 1998

2.3. Netperf

Author

 Rick Jones

Category

 Performance

Description

 Single connection bandwidth or latency tests for TCP, UDP, and DLPI.
 Includes provisions for CPU utilization measurement.

Automation

 Requires compilation (K&R C sufficient for all but-DHISTOGRAM, may
 require ANSI C in the future) if starting from source. Execution as
 child of inetd requires editing of /etc/services and /etc/inetd.conf.
 Scripts are provided for a quick look (snapshot_script), bulk
 throughput of TCP and UDP, and latency for TCP and UDP.  It is
 command-line driven.

Availability

 See http://www.cup.hp.com/netperf/NetperfPage.html or e-mail Rick
 Jones (raj@cup.hp.com). Binaries are available here for HP/UX Irix,
 Solaris, and Win32.

Required Environment

 C language compiler, POSIX.1, sockets.

2.4. NIST Net

Author

 Mark Carson

Category

 Functional Correctness / Performance

Description

 NIST Net is a network emulator. The tool is packaged as a Linux
 kernel patch, a kernel module, a set of programming APIs, and
 command-line and X-based user interfaces.
 NIST Net works by turning the system into a "selectively bad" router
 - incoming packets may be delayed, dropped, duplicated, bandwidth-
 constrained, etc.  Packet delays may be fixed or randomly
 distributed, with loadable probability distributions.  Packet loss
 may be uniformly distributed (constant loss probability) or
 congestion-dependent (probability of loss increases with packet queue
 lengths).  Explicit congestion notifications may optionally be sent

Parker & Schmechel Informational [Page 4] RFC 2398 Some Testing Tools for TCP Implementors August 1998

 in place of congestion-dependent loss.

Automation

 To control the operation of the emulator, there is an interactive
 user interface, a non-interactive command-line interface, and a set
 of APIs.  Any or all of these may be used in concert.  The
 interactive interface is suitable for simple, spur-of-the-moment
 testing, while the command-line or APIs may be used to create
 scripted, non-interactive tests.

Availability

 NIST Net is available for public download from the NIST Net web site,
 http://www.antd.nist.gov/itg/nistnet/.  The web site also has
 installation instructions and documentation.

Required Environment

 NIST Net requires a Linux installtion, with kernel version 2.0.27 -
 2.0.33.  A kernel source tree and build tools are required to build
 and install the NIST Net components.  Building the X interface
 requires a version of XFree86 (Current Version is 3.3.2).  An
 Athena-replacement widget set such as neXtaw
 (http://www.inf.ufrgs.br/~kojima/nextaw/) is also desirable for an
 improved user interface.
 NIST Net should run on any i386-compatible machine capable of running
 Linux, with one or more interfaces.

2.5. Orchestra

Author

 Scott Dawson, Farnam Jahanian, and Todd Mitton

Category

 Functional Correctness / Performance

Description

 This tool is a library which provides the user with an ability to
 build a protocol layer capable of performing fault injection on
 protocols.  Several fault injection layers have been built using this
 library, one of which has been used to test different vendor
 implementations of TCP. This is accomplished by probing the vendor
 implementation from one machine containing a protocol stack that has
 been instrumented with Orchestra.  A connection is opened from the
 vendor TCP implementation to the machine which has been instrumented.
 Faults may then be injected at the Orchestra side of the connection
 and the vendor TCP's response may be monitored.  The most recent
 version of Orchestra runs inside the X-kernel protocol stack on the
 OSF MK operating system.

Parker & Schmechel Informational [Page 5] RFC 2398 Some Testing Tools for TCP Implementors August 1998

 When using Orchestra to test a protocol, the fault injection layer is
 placed below the target protocol in the protocol stack.  This can
 either be done on one machine on the network, if protocol stacks on
 the other machines cannot be modified (as in the case of testing
 TCP), or can be done on all machines on the network (as in the case
 of testing a protocol under development).  Once the fault injection
 layer is in the protocol stack, all messages sent by and destined for
 the target protocol pass through it on their way to/from the network.
 The Orchestra fault injection layer can manipulate these messages.
 In particular, it can drop, delay, re-order, duplicate, or modify
 messages.  It can also introduce new messages into the system if
 desired.
 The actions of the Orchestra fault injection layer on each message
 are determined by a script, written in Tcl.  This script is
 interpreted by the fault injection layer when the message enters the
 layer.  The script has access to the header information about the
 message, and can make decisions based on header values.  It can also
 keep information about previous messages, counters, or any other data
 which the script writer deems useful.  Users of Orchestra may also
 define their own actions to be taken on messages, written in C, that
 may be called from the fault injection scripts.

Automation

 Scripts can be specified either using a graphical user interface
 which generates Tcl, or by writing Tcl directly.  At this time,
 post-analysis of the results of the test must also be performed by
 the user.  Essentially this consists of looking at a packet trace
 that Orchestra generates for (in)correct behavior.  Must compile and
 link fault generated layer with the protocol stack.

Availability

 See http://www.eecs.umich.edu/RTCL/projects/orchestra/ or e-mail
 Scott Dawson (sdawson@eecs.umich.edu).

Required Environment OSF MK operating system, or X-kernel like network

 architecture, or adapted to network stack.

References

 [DJ94], [DJM96a], [DJM96b]

Parker & Schmechel Informational [Page 6] RFC 2398 Some Testing Tools for TCP Implementors August 1998

2.6. Packet Shell

Author

 Steve Parker and Chris Schmechel

Category

 Functional Correctness / Performance

Description

 An extensible Tcl/Tk based software toolset for protocol development
 and testing. Tcl (Tool Command Language) is an embeddable scripting
 language and Tk is a graphical user interface toolkit based on Tcl.
 The Packet Shell creates Tcl commands that allow you to create,
 modify, send, and receive packets on networks.  The operations for
 each protocol are supplied by a dynamic linked library called a
 protocol library.  These libraries are silently linked in from a
 special directory when the Packet Shell begins execution. The current
 protocol libraries are: IP, IPv6, IPv6 extensions, ICMP, ICMPv6,
 Ethernet layer, data layer, file layer (snoop and tcpdump support),
 socket layer, TCP, TLI.
 It includes harness, which is a Tk based graphical user interface for
 creating test scripts within the Packet Shell.  It includes tests for
 no initial slow start, and retain out of sequence data as TCP test
 cases mentioned in [PADHV98].
 It includes tcpgraph, which is used with a snoop or tcpdump capture
 file to produce a TCP time-sequence plot using xplot.

Automation

 Command-line driven through Tcl commands, or graphical user interface
 models are available through the harness format.

Availability

 See http://playground.sun.com/psh/ or e-mail owner-packet-
 shell@sunroof.eng.sun.com.

Required Environment

 Solaris 2.4 or higher.  Porting required for other operating systems.

Parker & Schmechel Informational [Page 7] RFC 2398 Some Testing Tools for TCP Implementors August 1998

2.7. Tcpanaly

Author

 Vern Paxson

Category

 Functional Correctness / Performance

Description

 This is a tool for automatically analyzing a TCP implementation's
 behavior by inspecting packet traces of the TCP's activity. It does
 so through packet filter traces produced by tcpdump.  It has coded
 within it knowledge of a large number of TCP implementations.  Using
 this, it can determine whether a given trace appears consistent with
 a given implementation, and, if so, exactly why the TCP chose to
 transmit each packet at the time it did.  If a trace is found
 inconsistent with a TCP, tcpanaly either diagnoses a likely
 measurement error present in the trace, or indicates exactly whether
 the activity in the trace deviates from that of the TCP, which can
 greatly aid in determining how the traced implementation behaves.
 Tcpanaly's category is somewhat difficult to classify, since it
 attempts to profile the behavior of an implementation, rather than to
 explicitly test specific correctness or performance issues. However,
 this profile identifies correctness and performance problems.
 Adding new implementations of TCP behavior is possible with tcpanaly
 through the use of C++ classes.

Automation

 Command-line driven and only the traces of the TCP sending and
 receiving bulk data transfers are needed as input.

Availability

 Contact Vern Paxson (vern@ee.lbl.gov).

Required Environment

 C++ compiler.

References

 [Pax97a]

Parker & Schmechel Informational [Page 8] RFC 2398 Some Testing Tools for TCP Implementors August 1998

2.8. Tcptrace

Author

 Shawn Ostermann

Category

 Functional Correctness / Performance

Description

 This is a TCP trace file analysis tool. It reads output trace files
 in the formats of : tcpdump, snoop, etherpeek, and netm.
 For each connection, it keeps track of elapsed time, bytes/segments
 sent and received, retransmissions, round trip times, window
 advertisements, throughput, etc from simple to very detailed output.
 It can also produce three different types of graphs:
 Time Sequence Graph (shows the segments sent and ACKs returned as a
 function of time)
 Instantaneous Throughput (shows the instantaneous, averaged over a
 few segments, throughput of the connection as a function of time).
 Round Trip Times (shows the round trip times for the ACKs as a
 function of time)

Automation

 Command-line driven, and uses the xplot program to view the graphs.

Availability

 Source code is available, and Solaris binary along with sample
 traces. See http://jarok.cs.ohiou.edu/software/tcptrace/tcptrace.html
 or e-mail Shawn Ostermann (ostermann@cs.ohiou.edu).

Required Environment

 C compiler, Solaris, FreeBSD, NetBSD, HPUX, Linux.

Parker & Schmechel Informational [Page 9] RFC 2398 Some Testing Tools for TCP Implementors August 1998

2.9. Tracelook

Author

 Greg Minshall

Category

 Functional Correctness / Performance

Description

 This is a Tcl/Tk program for graphically viewing the contents of
 tcpdump trace files.  When plotting a connection, a user can select
 various variables to be plotted. In each direction of the connection,
 the user can plot the advertised window in each packet, the highest
 sequence number in each packet, the lowest sequence number in each
 packet, and the acknowledgement number in each packet.

Automation

 Command-line driven with a graphical user interface for the graph.

Availability

 See http://www.ipsilon.com/~minshall/sw/tracelook/tracelook.html or
 e-mail Greg Minshall (minshall@ipsilon.com).

Required Environment

 A modern version of awk, and Tcl/Tk (Tk version 3.6 or higher).  The
 program xgraph is required to view the graphs under X11.

2.10. TReno

Author

 Matt Mathis and Jamshid Mahdavi

Category

 Performance

Description

 This is a TCP throughput measurement tool based on sending UDP or
 ICMP packets in patterns that are controlled at the user-level so
 that their timing reflects what would be sent by a TCP that observes
 proper congestion control (and implements SACK).  This allows it to
 measure throughput independent of the TCP implementation of end hosts
 and serve as a useful platform for prototyping TCP changes.

Automation

 Command-line driven.  No "server" is required, and it only requires a
 single argument of the machine to run the test to.

Parker & Schmechel Informational [Page 10] RFC 2398 Some Testing Tools for TCP Implementors August 1998

Availability

 See http://www.psc.edu/networking/treno_info.html or e-mail Matt
 Mathis (mathis@psc.edu) or Jamshid Mahdavi (mahdavi@psc.edu).

Required Environment

 C compiler, POSIX.1, raw sockets.

2.11. Ttcp

Author

 Unknown

Category

 Performance

Description

 Originally written to move files around, ttcp became the classic
 throughput benchmark or load generator, with the addition of support
 for sourcing to/from memory. It can also be used as a traffic
 absorber. It has spawned many variants, recent ones include support
 for UDP, data pattern generation, page alignment, and even alignment
 offset control.

Automation

 Command-line driven.

Availability

 See ftp://ftp.arl.mil/pub/ttcp/ or e-mail ARL (ftp@arl.mil) which
 includes the most common variants available.

Required Environment

 C compiler, BSD sockets.

2.12. Xplot

Author

 Tim Shepard

Category

 Functional Correctness / Performance

Description

 This is a fairly conventional graphing/plotting tool (xplot itself),
 a script to turn tcpdump output into xplot input, and some sample
 code to generate xplot commands to plot the TCP time-sequence graph).

Automation

 Command-line driven with a graphical user interface for the plot.

Parker & Schmechel Informational [Page 11] RFC 2398 Some Testing Tools for TCP Implementors August 1998

Availability

 See ftp://mercury.lcs.mit.edu/pub/shep/xplot.tar.gz or e-mail Tim
 Shepard (shep@lcs.mit.edu).

Required Environment

 C compiler, X11.

References

 [She91]

3. Summary

 This memo lists all TCP tests and testing tools reported to the
 authors as part of TCP Implementer's working group and is not
 exhaustive.  These tools have been verified as available by the
 authors.

4. Security Considerations

 Network analysis tools are improving at a steady pace.  The
 continuing improvement in these tools such as the ones described make
 security concerns significant.
 Some of the tools could be used to create rogue packets or denial-
 of-service attacks against other hosts.  Also, some of the tools
 require changes to the kernel (foreign code) and might require root
 privileges to execute.  So you are trusting code that you have
 fetched from some perhaps untrustworthy remote site.  This code could
 contain malicious code that could present any kind of attack.
 None of the listed tools evaluate security in any way or form.
 There are privacy concerns when grabbing packets from the network in
 that you are now able to read other people's mail, files, etc.  This
 impacts more than just the host running the tool but all traffic
 crossing the host's physical network.

5. References

 [DJ94]    Scott Dawson and Farnam Jahanian, "Probing and Fault
           Injection of Distributed Protocol Implementations",
           University of Michigan Technical Report CSE-TR-217-94, EECS
           Department.
 [DJM96a]  Scott Dawson, Farnam Jahanian, and Todd Mitton, "ORCHESTRA:
           A Fault Injection Environment for Distributed Systems",
           University of Michigan Technical Report CSE-TR-318-96, EECS
           Department.

Parker & Schmechel Informational [Page 12] RFC 2398 Some Testing Tools for TCP Implementors August 1998

 [DJM96b]  Scott Dawson, Farnam Jahanian, and Todd Mitton,
           "Experiments on Six Commercial TCP Implementations Using a
           Software Fault Injection Tool", University of Michigan
           Technical Report CSE-TR-298-96, EECS Department.
 [Pax97a]  Vern Paxson, "Automated Packet Trace Analysis of TCP
           Implementations", ACM SIGCOMM '97, September 1997, Cannes,
           France.
 [PADHV98] Paxson, V., Allman, M., Dawson, S., Heavens, I., and B.
           Volz, "Known TCP Implementation Problems", Work In
           Progress.
 [Riz97]   Luigi Rizzo, "Dummynet: a simple approach to the evaluation
           of network protocols", ACM Computer Communication Review,
           Vol. 27, N. 1, January 1997, pp.  31-41.
 [She91]   Tim Shepard, "TCP Packet Trace Analysis", MIT Laboratory
           for Computer Science MIT-LCS-TR-494, February, 1991.

Parker & Schmechel Informational [Page 13] RFC 2398 Some Testing Tools for TCP Implementors August 1998

6. Authors' Addresses

 Steve Parker
 Sun Microsystems, Inc.
 901 San Antonio Road, UMPK17-202
 Palo Alto, CA 94043
 USA
 Phone: (650) 786-5176
 EMail: sparker@eng.sun.com
 Chris Schmechel
 Sun Microsystems, Inc.
 901 San Antonio Road, UMPK17-202
 Palo Alto, CA, 94043
 USA
 Phone: (650) 786-4053
 EMail: cschmec@eng.sun.com

Parker & Schmechel Informational [Page 14] RFC 2398 Some Testing Tools for TCP Implementors August 1998

7. Full Copyright Statement

 Copyright (C) The Internet Society (1998).  All Rights Reserved.
 This document and translations of it may be copied and furnished to
 others, and derivative works that comment on or otherwise explain it
 or assist in its implementation may be prepared, copied, published
 and distributed, in whole or in part, without restriction of any
 kind, provided that the above copyright notice and this paragraph are
 included on all such copies and derivative works.  However, this
 document itself may not be modified in any way, such as by removing
 the copyright notice or references to the Internet Society or other
 Internet organizations, except as needed for the purpose of
 developing Internet standards in which case the procedures for
 copyrights defined in the Internet Standards process must be
 followed, or as required to translate it into languages other than
 English.
 The limited permissions granted above are perpetual and will not be
 revoked by the Internet Society or its successors or assigns.
 This document and the information contained herein is provided on an
 "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
 TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
 BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Parker & Schmechel Informational [Page 15]

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