rfc2647.txt

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   Definition:
     The length of time needed for two hosts, or a host and the DUT/SUT,
     to agree to set up a connection using a known protocol.

   Discussion:
     Each connection-oriented protocol has its own defined mechanisms
     for setting up a connection. For purposes of benchmarking firewall
     performance, this shall be the interval between receipt of the
     first bit of the first octet of the packet carrying a connection
     establishment request on a DUT/SUT interface until transmission of
     the last bit of the last octet of the last packet of the connection
     setup traffic headed in the opposite direction.





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     This definition applies only to connection-oriented protocols such
     as TCP. For connectionless protocols such as UDP, the notion of
     connection establishment time is not meaningful.

   Unit of measurement:
     Connection establishment time

   Issues:

   See also:
     concurrent connections
     connection
     connection maintenance

3.10 Connection maintenance

   Definition:
     The data exchanged between hosts, or between a host and the
     DUT/SUT, to ensure a connection is kept alive.

   Discussion:
     Some implementations of TCP and other connection-oriented protocols
     use "keep-alive" data to maintain a connection during periods where
     no user data is exchanged.

     When benchmarking firewall performance, it is useful to identfy
     connection maintenance traffic as distinct from UOTs per second.
     Given that maintenance traffic may be characterized by short bursts
     at periodical intervals, it may not be possible to describe a
     steady-state forwarding rate for maintenance traffic. One possible
     approach is to identify the quantity of maintenance traffic, in
     bytes or bits, over a given interval, and divide through to derive
     a measurement of maintenance traffic forwarding rate.

   Unit of measurement:
     maintenance traffic
     forwarding rate

   See also:
     connection
     connection establishment time
     connection teardown
     connection teardown time

   Issues:
     not applicable





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3.11 Connection overhead

   Definition:
     The degradation in bit forwarding rate, if any, observed as a
     result of the addition of one connection between two hosts through
     the DUT/SUT, or the addition of one connection from a host to the
     DUT/SUT.

   Discussion:
     The memory cost of connection establishment and maintenance is
     highly implementation-specific. This metric is intended to describe
     that cost in a method visible outside the firewall.

     It may also be desirable to invert this metric to show the
     performance improvement as a result of tearing down one connection.

   Unit of measurement:
     bit forwarding rate

   Issues:

3.12 Connection teardown

   Definition:
     The data exchanged between hosts, or between a host and the
     DUT/SUT, to close a connection.

   Discussion:
     Connection-oriented protocols like TCP follow a stated procedure
     when ending a connection. When benchmarking firewall performance,
     it is important to identify the teardown procedure so that it is
     not included in measurements of bit forwarding rate or UOTs per
     second.

     Testers may also be interested in measurements of connection
     teardown time through or with a given DUT/SUT.

   Unit of measurement:
     not applicable

   See also:
     connection teardown time

   Issues:
     not applicable






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3.13 Connection teardown time

   Definition:
     The length of time needed for two hosts, or a host and the DUT/SUT,
     to agree to tear down a connection using a known protocol.

   Discussion:
     Each connection-oriented protocol has its own defined mechanisms
     for dropping a connection. For purposes of benchmarking firewall
     performance, this shall be the interval between receipt of the
     first bit of the first octet of the packet carrying a connection
     teardown request on a DUT/SUT interface until transmission of the
     last bit of the last octet of the last packet of the connection
     teardown traffic headed in the opposite direction.

     This definition applies only to connection-oriented protocols such
     as TCP. For connectionless protocols such as UDP, the notion of
     connection teardown time is not meaningful.

   Unit of measurement:
     Connection teardown time

   Issues:

   See also:
     concurrent connections
     connection
     connection maintenance

3.14 Data source

   Definition:
     A host capable of generating traffic to the DUT/SUT.

   Discussion:
     One data source may emulate multiple users or hosts. In addition,
     one data source may offer traffic to multiple network interfaces on
     the DUT/SUT.

     The term "data source" is deliberately independent of any number of
     users. It is useful to think of data sources simply as traffic
     generators, without any correlation to any given number of users.

   Unit of measurement:
     not applicable

   Issues:
     user



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   See also:
     connection
     user

3.15 Demilitarized zone

   Definition:
     A network segment or segments located between protected and
     unprotected networks.

   Discussion:
     As an extra security measure, networks may be designed such that
     protected and unprotected segments are never directly connected.
     Instead, firewalls (and possibly public resources such as HTTP or
     FTP servers) reside on a so-called DMZ network.

     DMZ networks are sometimes called perimeter networks.

   Unit of measurement:
     not applicable

   Issues:
     Homed

   See also:
     protected network
     unprotected network

3.16 Firewall

   Definition:
     A device or group of devices that enforces an access control policy
     between networks.

   Discussion:
     While there are many different ways to accomplish it, all firewalls
     do the same thing: control access between networks.

     The most common configuration involves a firewall connecting two
     segments (one protected and one unprotected), but this is not the
     only possible configuration. Many firewalls support tri-homing,
     allowing use of a DMZ network. It is possible for a firewall to
     accommodate more than three interfaces, each attached to a
     different network segment.

     The criteria by which access are controlled are not specified here.
     Typically this has been done using network- or transport-layer
     criteria (such as IP subnet or TCP port number), but there is no



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     reason this must always be so. A growing number of firewalls are
     controlling access at the application layer, using user
     identification as the criterion. And firewalls for ATM networks may
     control access based on data link-layer criteria.

   Unit of measurement:
     not applicable

   Issues:

   See also:
     DMZ
     tri-homed
     user

3.17 Goodput

   Definition:
     The number of bits per unit of time forwarded to the correct
     destination interface of the DUT/SUT, minus any bits lost or
     retransmitted.

   Discussion:
     Firewalls are generally insensitive to packet loss in the network.
     As such, measurements of gross bit forwarding rates are not
     meaningful since (in the case of proxy-based and stateful packet
     filtering firewalls) a receiving endpoint directly attached to a
     DUT/SUT would not receive any data dropped by the DUT/SUT.

     The type of traffic lost or retransmitted is protocol-dependent.
     TCP and ATM, for example, request different types  of
     retransmissions.  Testers must observe retransmitted data for the
     protocol in use, and subtract this quantity from measurements of
     gross bit forwarding rate.

   Unit of measurement:
     bits per second

   Issues:
     allowed vs. rejected traffic

   See also:
     allowed traffic
     bit forwarding rate
     rejected traffic






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3.18 Homed

   Definition:
     The number of logical interfaces a DUT/SUT contains.

   Discussion:
     Firewalls typically contain at least two logical interfaces. In
     network topologies where a DMZ is used, the firewall usually
     contains at least three interfaces and is said to be tri-homed.
     Additional interfaces would make a firewall quad-homed, quint-
     homed, and so on.

     It is theoretically possible for a firewall to contain one physical
     interface and multiple logical interfaces. This configuration is
     discouraged for testing purposes because of the difficulty in
     verifying that no leakage occurs between protected and unprotected
     segments.

   Unit of measurement:
     not applicable

   Issues:

   See also:
     tri-homed

3.19 Illegal traffic

   Definition:
     Packets specified for rejection in the rule set of the DUT/SUT.

   Discussion:
     A buggy or misconfigured firewall might forward packets even though
     its rule set specifies that these packets be dropped. Illegal
     traffic differs from rejected traffic in that it describes all
     traffic specified for rejection by the rule set, while rejected
     traffic specifies only those packets actually dropped by the
     DUT/SUT.

   Unit of measurement:
     not applicable

   Issues:








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   See also:
     accepted traffic
     policy
     rejected traffic
     rule set

3.20 Logging

   Definition:
     The recording of user requests made to the firewall.

   Discussion:
     Firewalls typically log all requests they handle, both allowed and
     rejected. For many firewall designs, logging requires a significant
     amount of processing overhead, especially when complex rule sets
     are in use.

     The type and amount of data logged varies by implementation.
     Testers may find it desirable to log equivalent data when comparing
     different DUT/SUTs.

     Some systems allow logging to take place on systems other than the
     DUT/SUT.

   Unit of measurement:
     not applicable

   Issues:
     rule sets

   See also:
     allowed traffic
     connection
     rejected traffic

3.21 Network address translation

   Definition:
     A method of mapping one or more private, reserved IP addresses to
     one or more public IP addresses.

   Discussion:
     In the interest of conserving the IPv4 address space, RFC 1918
     proposed the use of certain private (reserved) blocks of IP
     addresses. Connections to public networks are made by use of a
     device that translates one or more RFC 1918 addresses to one or
     more public addresses--a network address translator (NAT).




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     The use of private addressing also introduces a security benefit in
     that RFC 1918 addresses are not visible to hosts on the public
     Internet.

     Some NAT implementations are computationally intensive, and may
     affect bit forwarding rate.

   Unit of measurement:
     not applicable

   Issues:

   See also:

3.22  Packet filtering

   Definition:
     The process of controlling access by examining packets based on the
     content of packet headers.

   Discussion:
     Packet-filtering devices forward or deny packets based on
     information in each packet's header, such as IP address or TCP port
     number. A packet-filtering firewall uses a rule set to determine
     which traffic should be forwarded and which should be blocked.

   Unit of measurement:
     not applicable

   Issues:
     static vs. stateful packet filtering

   See also:
     application proxy
     circuit proxy
     proxy
     rule set
     stateful packet filtering

3.23 Policy

   Definition:
     A document defining acceptable access to protected, DMZ, and
     unprotected networks.







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   Discussion:
     Security policies generally do not spell out specific
     configurations for firewalls; rather, they set general guidelines
     for what is and is not acceptable network access.

     The actual mechanism for controlling access is usually the rule set
     implemented in the DUT/SUT.

   Unit of measurement:
     not applicable

   Issues:

   See also:
     rule set