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         Benchmarking Working Group                               D. Newman
         INTERNET-DRAFT                                 Data Communications
         Expires in January 1998         H. Holzbaur, J. Hurd, and S. Platt
                                     National Software Testing Laboratories
         
                   Benchmarking Terminology for Network Security Devices
                           <draft-ietf-bmwg-secperf-00.txt>
         
         Status of This Memo
         
         This document is an Internet-Draft.  Internet-Drafts are working
         documents of the Internet Engineering Task Force (IETF), its
         areas, and its working groups.  Note that other groups may also
         distribute working documents as Internet-Drafts.
         
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         Coast), or ftp.isi.edu (US West Coast).
         
         This memo provides information for the Internet community.  This
         memo does not specify an Internet standard of any kind.
         Distribution of this memo is unlimited.
         
         1. Introduction
         Despite the rapid rise in deployment of network security devices
         such as firewalls and authentication/encryption products, there is
         no standard method for evaluating the performance of these
         devices.
         
         The lack of a standard is troubling for two reasons. First,
         hardware and software implementations vary widely, making it
         difficult to do direct performance comparisons. Second, a growing
         number of organizations are deploying these devices on internal
         networks that operate at relatively high data rates, while many
         network security devices are optimized for use over relatively
         low-speed wide-area connections. As a result, users are often
         unsure whether the products they buy will stand up to the
         relatively heavy loads found on internal networks.
         
         This document defines terms used in measuring the performance of
         network security devices. It extends the terminology already used
         for benchmarking routers and switches to network security devices.
         The primary metrics defined in this document are maximum
         forwarding rate and maximum number of connections.
         
         Depending on the outcome of discussions within the BMWG, we may
         also attempt to classify devices using various architectural
         considerations (proxy, packet filter) or offered load levels
         
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         (high, medium, low) as criteria. Additionally, new metrics may
         need to be defined to evaluate application-level issues.
         
         2. Existing definitions
         This document uses the conceptual framework established in RFCs
         1242 and 1944 and draft-ietf-bmwg-lanswitch-05.txt, which
         describes benchmarking of LAN
         switch performance. In addition to defining basic practices, these
         documents
         contain discussions of several terms relevant to benchmarking
         performance of network security devices. This document uses the
         definition format described in RFC 1242, Section 2. Readers should
         consult these documents before making use of this document.
         
         3. Term definitions
         
         3.1 Authentication
         
         Definition:
         The process of verifying that a client user or machine requesting
         a network resource is who he, she, or it claims to be, and vice
         versa.
         
         Discussion:
         Trust is a critical concept in network security. Obviously, any
         network resource (such as a file server or printer) with
         restricted access MUST require authentication before granting
         access.
         
         Authentication takes many forms, including but not limited to IP
         addresses; TCP or UDP port numbers; passwords; external token
         authentication cards; and pattern matching based on human
         characteristics such as signature, speech, or retina patterns.
         
         Authentication MAY work either by client machine (for example, by
         proving that a given IP source address really is that address, and
         not a rogue machine spoofing that address) or by user (by proving
         that the user really is who he or she claims to be). Servers
         SHOULD also authenticate themselves to clients.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         forwarding rate (3.9)
         user (3.25)
         virtual client (3.26)
         
         3.2 Bidirectional traffic
         
         Definition:
         
         
         
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         Packets presented to a DUT/SUT such that the network interfaces of
         the DUT/SUT both receive and transmit traffic.
         
         Discussion:
         Traffic patterns offered to the DUT/SUT MUST be bidirectional or
         fully meshed. See forwarding rate (3.9) for a more complete
         discussion of issues with traffic patterns.
         
         Measurement units:
         Not applicable
         
         Issues:
         truncated binary exponential back-off algorithm
         
         See Also:
         forwarding rate (3.9)
         fully meshed traffic (3.10)
         unidirectional traffic (3.24)
         
         3.3 Data source
         
         Definition:
         A station capable of generating traffic to the DUT/SUT.
         
         Discussion:
         One data source MAY emulate multiple users or stations. In
         addition, one data source MAY offer traffic to multiple network
         interfaces on the DUT/SUT. However, each virtual client MUST offer
         traffic to only one interface.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         user (3.25)
         virtual client (3.26)
         
         3.4 Demilitarized zone (DMZ)
         
         Definition:
         A network segment or segments located between protected and
         external networks. DMZ networks are sometimes called perimeter
         networks.
         
         Discussion:
         As an extra security measure, networks are often designed such
         that protected and external segments are never directly connected.
         Instead, security devices (and possibly other public resources
         such as WWW or FTP servers) often reside in the so-called DMZ
         network. To connect protected, DMZ, and external networks with one
         device, the device MUST have at least three network interfaces.
         
         
         
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         Multiple devices MAY constitute the DMZ, in which case the devices
         connected the protected network with the DMZ and the DMZ with the
         external network MUST have two network interfaces.
         
         Measurement units:
         Not applicable
         
         Issues:
         Dual-homed
         Multihomed
         
         See also:
         external network (3.8)
         perimeter network (3.15)
         protected network (3.17)
         
         3.5 Device under test (DUT)
         
         Definition:
         The network security device to which traffic is offered and
         response measured.
         
         Discussion:
         A single station, generally equipped with at least two network
         interfaces.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         system under test (SUT) (3.23)
         
         3.6 Dual-homed
         
         Definition:
         A station with at least two network interfaces.
         
         Discussion:
         Dual-homed network security devices connect two segments with
         different network-layer addresses.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         multihomed (3.12)
         
         3.7 Dynamic proxy
         
         Definition:
         
         
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         A proxy service that is set up and torn down in response to a
         client request, rather than existing on a static basis.
         
         Discussion:
         Proxy services (see section 3.18) typically are configured to
         "listen" on a given port number for client requests. However, some
         devices set up a proxy service only when a client requests the
         service.
         
         Measurement units:
         Not applicable
         
         Issues:
         rule sets
         
         See also:
         proxy (3.18)
         rule sets (3.20)
         
         3.8 External network
         
         Definition:
         The segment or segments not protected by the network security
         DUT/SUT.
         
         Discussion:
         Network security devices are deployed between protected and
         unprotected segments. The external network is not protected by the
         DUT/SUT.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         demilitarized zone (DMZ) (3.4)
         protected network (3.17)
         
         3.9 Forwarding rate
         
         Definition: The number of bits per second a DUT/SUT can transmit
         to the correct destination network interface in response to a
         specified offered load.
         
         Discussion:
         Network security devices are by definition session-oriented: They
         will only grant access to a desired resource once authentication
         occurs and a session has been established.
         
         Because application-layer sessions are always involved,
         unidirectional packet-per-second metrics are not meaningful in the
         context of testing network security devices. Instead, this
         
         
         
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         definition MUST measure application-layer performance once a
         session has been established.
         
         Forwarding rate refers to the number of bits per second observed
         on the output side of the network interface under test. Forwarding
         rate can be measured with different traffic orientations and
         distributions. When multiple network interfaces are measured,
         measurements MUST be observed from the interface with the highest
         forwarding rate.
         
         Measurement units:
         bits per second (bit/s)
         kilobits per second (kbit/s)
         Megabits per second (Mbit/s)
         
         Issues:
         truncated binary exponential back-off algorithm
         unidirectional vs. bidirectional
         
         See Also:
         authentication (3.1)
         maximum forwarding rate (3.11)
         offered load (3.13)
         unidirectional traffic (3.24)
         
         3.10 Fully meshed traffic
         
         Definition:
         Packets forwarded simultaneously among all of a designated number
         of network interfaces of a DUT/SUT such that each of the
         interfaces under test will both forward packets to and receive
         packets from all of the other interfaces.
         
         Discussion:
         Fully meshed traffic is the most thorough method of exercising the
         transmitting and receiving capabilities of the DUT/SUT.
         
         Unlike past definitions for router or switch testing, it should be
         noted that fully meshed traffic in this context is not necessarily
         symmetrical. While all of a designated group of network interfaces
         MUST simultaneously send and receive traffic, the type and amount
         of traffic offered MAY differ on each interface. For example, a
         network security device may see more traffic from the protected
         network bound for the external network than the opposite (although
         the inverse could be true during an attack on the DUT/SUT).
         
         Measurement units:
         Not applicable
         
         Issues:
         Half duplex
         Full duplex
         
         See also:
         
         
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         bidirectional traffic (3.2)
         unidirectional traffic (3.24)
         
         3.11 Maximum forwarding rate
         
         Definition:
         The highest forwarding rate of a network security device taken
         from a set of iterative measurements.
         
         Discussion:
         Maximum forwarding rate may degrade before maximum load is
         offered.
         
         Unlike benchmarks for evaluating router and switch performance,
         this definition MUST involve measurement of application-layer
         performance rather than network-layer packet-per-second metrics.
         
         Measurement units:
         Megabits per second
         kbytes per second
         bytes per second
         
         Issues:
         full duplex vs. half duplex
         truncated binary exponential back-off algorithm
         
         See also:
         bidirectional traffic (3.2)
         partially meshed traffic (3.24)
         unidirectional traffic
         
         3.12 Multihomed
         
         Definition:
         A network security device with more than two network interfaces.
         
         Discussion:
         Multihoming is a way to connect three or more networks-protected,
         DMZ, and external-with a single network security device. However,
         this configuration is not mandatory if multiple network security
         devices are used. For example, one device could secure the
         connection between an external and DMZ network, while another
         could secure the connection between a DMZ and protected network;
         the two stations collectively form the SUT.
         
         Because of the differences in traffic patterns between dual-homed
         and multihomed devices, direct performance comparisons should be
         avoided. However, it is acceptable to compare results between a
         dual-homed device and a DUT/SUT in which only two network
         interfaces are used.
         
         Measurement units:
         Not applicable
         
         
         
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         Issues:
         truncated binary exponential back-off algorithm
         
         See also:
         bidirectional traffic (3.2)
         dual-homed (3.6)
         fully meshed traffic (3.10)
         
         3.13 Offered load
         
         Definition:
         The number of bits per second that an external source can transmit
         to a DUT/SUT for forwarding to a specified network interface or
         interfaces.
         
         Discussion:
         The load that an external source actually applies to a DUT/SUT may
         be lower than the external source attempts to apply because of
         collisions on the wire. The transmission capabilities of the
         external source SHOULD be verified without the DUT/SUT by
         transmitting unidirectional traffic.
         
         Measurement units:
         bits per second
         kilobits per second (kbit/s)
         Megabits per second (Mbit/s)
         
         Issues:
         truncated binary exponential back-off algorithm
         
         See also:
         forwarding rate (3.9)
         maximum forwarding rate (3.11)
         
         3.14 Packet filtering
         
         Definition:
         The process of controlling access by examining packets based on
         network-layer or transport-layer criteria.
         
         Discussion:
         Packet-filtering devices forward or deny packets based on
         information in each packet's header. A packet-filtering network
         security device uses a rule set (see section 3.20) to determine
         which traffic should be forwarded and which should be blocked.
         Packet filtering may be used in a dual-homed or multihomed device.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         dynamic proxy (3.7)
         
         
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         proxy (3.18)
         rule set (3.20)
         stateful inspection (3.22)
         
         3.15 Perimeter network
         
         Definition:
         A network segment or segments located between protected and
         external networks. Perimeter networks are often called DMZ
         networks.
         
         Discussion:
         See the definition of DMZ (which see) for a discussion.
         
         Measurement units:
         Not applicable
         
         Issues:
         Dual-homed
         Multihomed
         
         See also:
         Demilitarized zone (DMZ) (3.4)
         external network (3.8)
         protected network (3.17)
         
         3.16 Policy
         
         Definition:
         A document defining acceptable use of protected, DMZ, and external
         networks.
         
         Discussion:
         Security policies generally do not spell out specific
         configurations for network security devices; rather, they set
         general guidelines for what it and is not acceptable network
         behavior.
         
         The actual mechanism for controlling access is usually the rule
         set (see section 3.20) implemented in the DUT/SUT.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         Rule set (3.20)
         
         3.17 Protected network
         
         Definition:
         A network segment or segments to which access is controlled by the
         DUT/SUT.
         
         
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         Discussion:
         Network security devices are intended to prevent unauthorized
         access either to or from the protected network. Depending on the
         configuration specified by the policy and rule set, the DUT/SUT
         may allow stations on the protected segment to act as clients for
         servers on either the DMZ or the external network, or both.
         
         Protected networks are often called "internal networks." That term
         is not used here because network security devices increasingly are
         deployed within an organization, where all segments are by
         definition internal.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         Demilitarized zone (DMZ) (3.4)
         external network (3.8)
         policy (3.16)
         rule set (3.20)
         
         3.18 Proxy
         
         Definition:
         The process of requesting sessions with servers on behalf of
         clients.
         
         Discussion:
         Proxy-based network security devices never involve direct
         connections between client and server. Instead, two sessions are
         established: one between the client and the DUT/SUT, and another
         between the DUT/SUT and server.
         
         As with packet-filtering network security devices, proxy-based
         devices use a rule set (which see) to determine which traffic
         should be forwarded and which should be blocked.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         dynamic proxy (3.7)
         packet filtering (3.14)
         stateful inspection (3.22)
         
         3.19 Rejected traffic
         
         Definition:
         Packets dropped as a result of the rule set of the DUT/SUT.
         
         
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         Discussion:
         Network security devices typically are configured to drop any
         traffic not explicitly permitted in the rule set (which see).
         Dropped packets MUST NOT be included in calculating the forwarding
         rate or maximum forwarding rate of the DUT/SUT.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         forwarding rate (3.9)
         maximum forwarding rate (3.11)
         policy (3.16)
         rule set (3.20)
         
         3.20 Rule set
         
         Definition:
         The collection of definitions that determines which packets the
         DUT/SUT will forward and which it will reject.
         
         Discussion:
         Rule sets control access to and from the network interfaces of the
         DUT/SUT. By definition, rule sets MUST NOT apply equally to all
         network interfaces; otherwise there would be no need for the
         network security device. Therefore, a specific rule set MUST be
         applied to each network device used in the DUT/SUT.
         
         The order of rules within the rule set is critical. Network
         security devices generally scan rule sets in a "top down" fashion,
         which is to say that the device compares each packet received with
         each rule in the rule set until it finds a rule that applies to
         the packet. Once the device finds an applicable rule, it applies
         the actions defined in that rule (such as forwarding or rejecting
         the packet) and ignores all subsequent rules. For purposes of this
         document, the rule set MUST conclude with a rule denying all
         access except that which is permitted in the rule set.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         Demilitarized zone (DMZ) (3.4)
         external network (3.8)
         policy (3.17)
         protected network (3.18)
         rejected traffic (3.19)
         
         3.21 Session
         
         
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         Definition:
         A logical connection established between two stations using a
         known protocol. For purposes of this document, a session MUST be
         conducted over either TCP (RFC 793) or UDP (RFC 768).
         
         Discussion:
         Because of the application-layer focus of many network security
         devices, sessions are a more useful metric than the packet-based
         measurements used in benchmarking routers and switches. Although
         network security device rule sets generally work on a per-packet
         basis, it is ultimately sessions that a network security device
         must handle. For example, the number of file transfer protocol
         (ftp) sessions a DUT/SUT can handle concurrently is a more
         meaningful measurement in benchmarking performance than the number
         of ftp "open" packets it can reject. Further, a stateful
         inspection device (which see) will not forward individual packets
         if those packets' headers conflict with state information
         maintained in the device's rule set.
         
         For purposes of this document, a session MUST be established using
         a known protocol. A traffic pattern is not considered a session
         until it successfully completes the establishment procedures
         defined by that protocol.
         
         Also for purposes of this document, a session constitutes the
         logical connection between two end-stations and not the
         intermediate connections that proxy-based network security devices
         may use.
         
         Issues:
         
         See also:
         policy (3.16)
         proxy (3.18)
         rule set (3.20)
         stateful inspection (3.22)
         
         3.22 Stateful inspection
         
         Definition:
         The process of forwarding or rejecting traffic based on the
         contents of a state table maintained by the network security
         device.
         
         Discussion:
         Packet filtering and proxy devices are essentially static, in that
         they always forward or reject traffic based on the contents of the
         rule set. Devices using stateful inspection, in contrast, will
         only forward traffic if it corresponds with state information
         maintained by the device about each session. For example, a
         stateful inspection device will reject a packet on TCP port 21
         (ftp DATA) if no ftp session has been established.
         
         
         
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         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         dynamic proxy (3.7)
         packet filter (3.14)
         proxy (3.18)
         
         3.23 System under test (SUT)
         
         Definition:
         The collective set of network security devices to which traffic is
         offered as a single entity and response measured.
         
         Discussion:
         A system under test may comprise multiple network security
         devices. A typical configuration involves two or more devices,
         with at least one located between the protected network and DMZ
         and at least one other located between the DMZ and external
         network. Some devices may be active, such as firewalls or
         authentication products; other devices, such as systems for
         logging, may be passive.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         demilitarized zone (DMZ) (3.4)
         device under test (3.5)
         external network (3.8)
         protected network (3.17)
         
         3.24 Unidirectional traffic
         
         Definition:
         Packets offered to the DUT/SUT such that the sending and receiving
         network interface or interfaces are mutually exclusive.
         
         Discussion:
         This definition is included mainly for purposes of completeness;
         it is not particularly meaningful in the context of network
         security device performance. As noted in the discussion of
         forwarding rate (see section 3.9), network security devices almost
         invariably involve sessions with bidirectional traffic flow.
         
         However, unidirectional traffic is appropriate for evaluating the
         maximum forwarding rate of data sources (absent the DUT/SUT), and
         for evaluating the maximum forwarding rate of certain
         connectionless protocols.
         
         
         
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         Measurement units:
         Not applicable
         
         Issues:
         half duplex vs. full duplex
         
         See also:
         bidirectional traffic (3.2)
         forwarding rate (3.9)
         maximum forwarding rate (3.11)
         
         3.25 User
         
         Definition:
         The person or machine requesting access to resources protected by
         the DUT/SUT.
         
         Discussion:
         "User" is a problematic term in the context of security device
         performance testing, for several reasons. First, a user may in
         fact be a machine or machines requesting services through the
         DUT/SUT. Second, different "user" requests may require radically
         different amounts of DUT/SUT resources. Third, traffic profiles
         vary widely from one organization to another, making it difficult
         to characterize the load offered by a typical users. For these
         reasons, we prefer not to measure DUT/SUT performance in terms of
         users supported. Instead, we describe performance in terms of
         maximum forwarding rate and maximum number of sessions sustained.
         
         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         data source (3.3)
         virtual client (3.26)
         
         3.26 Virtual client
         
         Definition:
         A subset of a data source that represents one individual user.
         
         Discussion:
         In offering traffic to the DUT/SUT it may be useful for one data
         source to emulate multiple users, machines, or networks. For
         purposes of this document, each emulated user should be considered
         a virtual client.
         
         One data source MAY offer traffic from multiple virtual clients to
         multiple network interfaces on the DUT/SUT. However, each virtual
         client MUST offer traffic to just one network interface.
         
         
         
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         Measurement units:
         Not applicable
         
         Issues:
         
         See also:
         data source (3.3)
         user (3.25)
         
         4.  Security considerations
         Security considerations are explicitly excluded from this memo.
         The authors plan to address security and management concerns in a
         separate proposal brought to the IETF's security directorate.
         
         5. References
         
         Bradner, S., editor. "Benchmarking Terminology for Network
         Interconnection Devices." RFC 1242.
         
         Bradner, S., and McQuaid, J. "Benchmarking Methodology for Network
         Interconnect Devices." RFC 1944.
         
         Mandeville, B. "Benchmarking Terminology for LAN Switching
         Devices." ftp://ietf.org/internet-drafts/draft-ietf-bmwg-
         lanswitch-05.txt
         
         Newman, D., and Melson, B. "Can Firewalls Take the Heat?" Data
         Communications, November 21, 1995.
         http://www.data.com/Lab_Tests/Firewalls.html
         
         Newman, D., Holzbaur, H., and Bishop, K. "Firewalls: Don't Get
         Burned," Data Communications, March 21, 1997.
         http://www.data.com/lab_tests/firewalls97.html
         
         Ranum, M. "Firewall Performance Measurement Techniques: A
         Scientific Approach."
         http://www.clark.net/pub/mjr/pubs/fwperf/intro.htm
         
         Shannon, G. "Profile of Corporate Internet Application Traffic."
         http://www.milkyway.com/libr/prof.html
         
         6. Acknowledgments
         The authors wish to thank the IETF Benchmarking Working Group for
         agreeing to review this document. Ted Doty (Network Systems),
         Shlomo Kramer (Check Point Software Technologies), Bob Mandeville
         (European Network Laboratories), Brent Melson (National Software
         Testing Laboratories), Marcus Ranum (Network Flight Recorder
         Inc.), Greg Shannon (Milkyway Networks), Rick Siebenaler
         (Cyberguard), and Greg Smith (Check Point Software Technologies)
         offered valuable contributions and critiques during this project.
         
         7. Contact Information
         David Newman
         Data Communications magazine
         
         
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         1221 Avenue of the Americas, 41st Floor
         New York, NY 10020
         USA
         212-512-6182 voice
         212-512-6833 fax
         dnewman@data.com
         
         Helen Holzbaur
         National Software Testing Laboratories Inc.
         625 Ridge Pike
         Conshohocken, PA 19428
         USA
         helen@nstl.com
         
         Jim Hurd
         National Software Testing Laboratories Inc.
         625 Ridge Pike
         Conshohocken, PA 19428
         USA
         jimh@nstl.com
         
         Steven Platt, PhD.
         National Software Testing Laboratories Inc.
         625 Ridge Pike
         Conshohocken, PA 19428
         USA
         steve@nstl.com
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         Newman et al                                             [Page 16]
         

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