draft-ietf-bmwg-secperf-03.txt   draft-ietf-bmwg-secperf-04.txt 
Network Working Group D. Newman
Network Working Group D. Newman, editor
INTERNET-DRAFT Data Communications INTERNET-DRAFT Data Communications
Expires in January 1999 July 1998 Expires in January 1999 July 1998
Benchmarking Terminology for Firewall Performance Benchmarking Terminology for Firewall Performance
<draft-ietf-bmwg-secperf-03.txt> <draft-ietf-bmwg-secperf-04.txt>
Status of This Memo Status of This Memo
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1. Introduction ....................................................2 Table of Contents
Introduction .......................................................2
2. Existing definitions ............................................3 2. Existing definitions ............................................3
3. Term definitions ................................................3 3. Term definitions ................................................3
3.1 Allowed traffic ..............................................3 3.1 Allowed traffic .............................................3
3.2 Application proxy.............................................3 3.2 Application proxy ...........................................3
3.3 Authentication ...............................................4 3.3 Authentication ..............................................4
3.4 Bit forwarding rate ..........................................4 3.4 Bit forwarding rate .........................................5
3.5 Circuit proxy ................................................5 3.5 Circuit proxy ...............................................6
3.6 Concurrent connections .......................................6 3.6 Concurrent connections ......................................6
3.7 Connection ...................................................6 3.7 Connection ..................................................7
3.8 Connection establishment rate ................................7 3.8 Connection establishment rate ...............................8
3.9 Conection overhead ...........................................8 3.9 Connection overhead .........................................9
3.10 Data source .................................................8 3.10 Data source ................................................9
3.11 Demilitarized zone (DMZ) ....................................9 3.11 Demilitarized zone (DMZ) ..................................10
3.12 Firewall ....................................................9 3.12 Firewall ..................................................10
3.13 Goodput ...................................................11
3.13 Goodput ....................................................10 3.14 Homed .....................................................12
3.14 Homed ......................................................10
3.15 Illegal traffic.............................................11 3.15 Illegal traffic ...........................................12
3.16 Logging ....................................................11 3.16 Logging ...................................................13
3.17 Network address translation (NAT) ..........................12 3.17 Network address translation (NAT) .........................14
3.18 Packet filtering ...........................................12 3.18 Packet filtering ..........................................14
3.19 Perimeter network ..........................................13 3.19 Perimeter network .........................................15
3.20 Policy .....................................................13 3.20 Policy ....................................................15
3.21 Protected network ..........................................13 3.21 Protected network .........................................16
3.22 Proxy ......................................................14 3.22 Proxy .....................................................17
3.23 Rejected traffic ...........................................14 3.23 Rejected traffic ..........................................17
3.24 Rule set ...................................................15 3.24 Rule set ..................................................18
3.25 Stateful packet filtering ..................................15 3.25 Stateful packet filtering .................................18
3.26 Tri-homed ..................................................16 3.26 Tri-homed .................................................19
3.27 Unprotected network ........................................16 3.27 Unprotected network .......................................19
3.28 User .......................................................17 3.28 User ......................................................20
4. Security considerations ...........................................17 4. Security considerations ........................................21
5. References ........................................................18 5. References .....................................................21
6. Acknowledgments ...................................................18 6. Acknowledgments ................................................22
7. Contact information ...............................................19 7. Contact information ............................................22
1. Introduction 1. Introduction
This document defines terms used in measuring the performance of This document defines terms used in measuring the performance of
firewalls. It extends the terminology already used for benchmarking firewalls. It extends the terminology already used for benchmarking
routers and switches and adds terminology specific to firewalls. The routers and switches and adds terminology specific to firewalls. The
primary metrics used in this document are connections and bit primary metrics used in this document are bit forwarding rate and
forwarding rate. connections.
There are several reasons why are firewall performance measurements There are several reasons why firewall performance measurements are
are needed. First, despite the rapid rise in firewall deployment, needed. First, despite the rapid rise in firewall deployment, there
there is no standard means of performance measurement. Second, is no standard means of performance measurement. Second,
implementations vary widely, making it difficult to do direct implementations vary widely, making it difficult to do direct
performance comparisons. Finally, more and more organizations are performance comparisons. Finally, more and more organizations are
Newman Page [2]
deploying firewalls on internal networks operating at relatively high deploying firewalls on internal networks operating at relatively high
speeds, while most firewall implementations remain optimized for use speeds, while most firewall implementations remain optimized for use
over low-speed wide-area connections. As a result, users are often over low-speed wide-area connections. As a result, users are often
Newman Page [2]
unsure whether the products they buy will stand up to relatively unsure whether the products they buy will stand up to relatively
heavy loads. heavy loads.
2. Existing definitions 2. Existing definitions
This document uses the conceptual framework established in RFCs 1242 This document uses the conceptual framework established in RFCs 1242
and 1944 (for routers) and RFC 2285 (for switches). The router and and 1944 (for routers) and RFC 2285 (for switches). The router and
switch documents contain discussions of several terms relevant to switch documents contain discussions of several terms relevant to
benchmarking the performance of firewalls. Readers should consult the benchmarking the performance of firewalls. Readers should consult the
router and switch documents before making use of this document. router and switch documents before making use of this document.
This document uses the definition format described in RFC 1242, This document uses the definition format described in RFC 1242,
Section 2. The sections in each definition are: definition, Section 2. The sections in each definition are: definition,
discussion, measurement units (optional), issues (optional), and discussion, measurement units (optional), issues (optional), and
cross-references. cross-references.
skipping to change at line 132 skipping to change at line 137
This document uses the definition format described in RFC 1242, This document uses the definition format described in RFC 1242,
Section 2. The sections in each definition are: definition, Section 2. The sections in each definition are: definition,
discussion, measurement units (optional), issues (optional), and discussion, measurement units (optional), issues (optional), and
cross-references. cross-references.
3. Term definitions 3. Term definitions
3.1 Allowed traffic 3.1 Allowed traffic
Definition: Definition:
Packets forwarded as a result of the rule set of the device under Packets forwarded as a result of the rule set of the device under
test/system under test (DUT/SUT). test/system under test (DUT/SUT).
Discussion: Discussion:
Firewalls typically are configured to forward only those packets Firewalls typically are configured to forward only those packets
explicitly permitted in the rule set. Forwarded packets MUST be included explicitly permitted in the rule set. Forwarded packets MUST be
in calculating the bit forwarding rate or maximum bit forwarding rate of included in calculating the bit forwarding rate or maximum bit
the DUT/SUT. All other packets MUST NOT be included in bit forwarding forwarding rate of the DUT/SUT. All other packets MUST NOT be
rate calculations. included in bit forwarding rate calculations.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
policy
rule set policy rule set
3.2 Application proxy 3.2 Application proxy
Definition: Definition:
A proxy service that is set up and torn down in response to a client
request, rather than existing on a static basis. A type of proxy service that is application aware. As such these
proxies can ensure that only specific types of application
commands and data pass through; authenticate the user creating the
connection; dynamically open and close auxiliary ports sometimes
Newman Page [3]
required by applications.
Discussion: Discussion:
Circuit proxies always forward packets containing a given port number if
that port number is permitted by the rule set. Application proxies, in
contrast, forward packets only once a connection has been established
using some known protocol. When the connection closes, a firewall using
dynamic proxies rejects individual packets, even if they contain port
numbers allowed by a rule set.
Measurement units: Application proxies are aware of the type of data and application
commands that are expected to be associated with a given TCP or
UDP port and ensures that only such traffic is passed through
those ports. For example, TCP port 21 should only allow FTP
commands and responses through and not allow a non-FTP protocol to
be used for potentially malicious means. An application proxy also
can determine which dynamically allocated ports are required to
allow the service to work properly. In the case of FTP, it
requires that port 20 (ftp-data) be open for a period of time and
then closed after the transfer is complete.
Newman Page [3] Measurement units:
not applicable not applicable
Issues: Issues:
circuit proxy circuit proxy
rule sets rule sets
See also: See also:
allowed traffic allowed traffic
circuit proxy circuit proxy
proxy proxy rejected
rejected traffic traffic rule set
rule set
3.3 Authentication 3.3 Authentication
Definition: Definition:
The process of verifying that a user requesting a network resource is
who he, she, or it claims to be, and vice versa.
Discussion: The process of verifying that a user requesting a network resource
Trust is a critical concept in network security. Any network resource is who he, she, or it claims to be, and vice versa.
(such as a file server or printer) with restricted access MUST require
authentication before granting access. Discussion: Trust is a critical concept in network security. 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 Authentication takes many forms, including but not limited to IP
addresses; TCP or UDP port numbers; passwords; external token addresses; TCP or UDP port numbers; passwords; external token
authentication cards; and biometric identification such as signature, authentication cards; and biometric identification such as signature,
speech, or retina recognition systems. speech, or retina recognition systems.
The entity being authenticated MAY be the client machine (for example, The entity being authenticated MAY be the client machine (for
by proving that a given IP source address really is that address, and example, by proving that a given IP source address really is that
not a rogue machine spoofing that address) or a user (by proving that address, and not a rogue machine spoofing that address) or a user (by
the user really is who he, she, or it claims to be). Servers SHOULD also proving that the user really is who he, she, or it claims to be).
authenticate themselves to clients. Servers SHOULD also authenticate themselves to clients.
Testers should be aware that in an increasingly mobile society, Testers should be aware that in an increasingly mobile society,
authentication based on machine-specific criteria such as an IP address
or port number is not equivalent to verifying that a given individual is Newman Page [4]
making an access request. At this writing systems that verify the authentication based on machine-specific criteria such as an IP
identity of users are typically external to the firewall, and may address or port number is not equivalent to verifying that a given
introduce additional latency to the overall SUT. individual is making an access request. At this writing systems that
verify the identity of users are typically external to the firewall,
and may introduce additional latency to the overall SUT.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
user user
3.4 Bit forwarding rate 3.4 Bit forwarding rate
Definition: Definition:
The number of bits per second of allowed traffic a DUT/SUT can be
Newman Page [4]
observed to transmit to the correct destination interface(s) in response The number of bits per second of allowed traffic a DUT/SUT can be
to a specified offered load. observed to transmit to the correct destination interface(s) in
response to a specified offered load.
Discussion: Discussion:
This definition differs substantially from section 3.17 of RFC 1242 and
section 3.6.1 of RFC 2285.
Unlike both RFCs 1242 and 2285, this definition introduces the notion of This definition differs substantially from section 3.17 of RFC
different classes of traffic: allowed, illegal, and rejected (see 1242 and section 3.6.1 of RFC 2285.
definitions for each term). Any bit forwarding rate measurement MUST
include only allowed traffic.
Unlike RFC 1242, there is no reference to lost or retransmitted data. Unlike both RFCs 1242 and 2285, this definition introduces the
Forwarding rate is assumed to be a goodput measurement, in that only notion of different classes of traffic: allowed, illegal, and
data successfully forwarded to the destination interface is measured. rejected (see definitions for each term). Any bit forwarding rate
Bit forwarding rate MUST be measured in relation to the offered load. measurement MUST include only allowed traffic.
Bit forwarding rate MAY be measured with differed load levels, traffic
orientation, and traffic distribution.
Unlike RFC 2285, this measurement counts bits per second rather than Unlike RFC 1242, there is no reference to lost or retransmitted
frames per second. Per-frame metrics are not meaningful in the context data. Forwarding rate is assumed to be a goodput measurement, in
of a flow of application data between endpoints. that only data successfully forwarded to the destination interface
is measured. Bit forwarding rate MUST be measured in relation to
the offered load. Bit forwarding rate MAY be measured with
differed load levels, traffic orientation, and traffic
distribution.
Unlike RFC 2285, this measurement counts bits per second rather
than frames per second. Per-frame metrics are not meaningful in
the context of a flow of application data between endpoints.
Units of measurement: Units of measurement:
bits per second bits per second
Issues: Issues:
Allowed traffic vs. rejected traffic Allowed traffic vs. rejected traffic
Newman Page [5]
See also: See also:
allowed traffic allowed traffic
goodput goodput
illegal traffic illegal traffic
rejected traffic rejected traffic
3.5 Circuit proxy 3.5 Circuit proxy
Definition: Definition:
A proxy service that statically defines which traffic will be forwarded
using a criterion like port number. A type of proxy service that copies bytes between authorized
source and destinations for defined TCP ports. The data is copied
without any intelligent processing and the proxy cannot
dynamically open and close application specific auxiliary ports
that are sometimes required.
Discussion: Discussion:
The key distinction with circuit proxies is that they are static and
thus will always set up a connection if the DUT/SUT's rule set allows The key distinction with circuit proxies is that they are static
it. For example, if a firewall's rule set permits ftp connections, a and thus will always set up a connection if the DUT/SUT's rule set
circuit proxy will forward traffic on TCP port 20 (ftp default data) allows it. For example, if a firewall's rule set permits ftp
even if no control connection was first established on TCP port 21 (ftp connections, a circuit proxy will forward traffic on TCP port 20
control). (ftp default data) even if no control connection was first
established on TCP port 21 (ftp control).
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
application proxy
Newman Page [5]
application proxy
rule sets rule sets
See also: See also:
allowed traffic allowed traffic
application proxy application proxy
proxy proxy
rejected traffic rejected traffic
rule set rule set
3.6 Concurrent connections 3.6 Concurrent connections
Definition: Definition:
The aggregate number of simultaneous connections between hosts across
the DUT/SUT, or between hosts and the DUT/SUT. The aggregate number of simultaneous connections between hosts
across the DUT/SUT, or between hosts and the DUT/SUT.
Discussion: Discussion:
The number of concurrent connections a firewall can support is just as
important a metric for some users as maximum bit forwarding rate. The number of concurrent connections a firewall can support is
just as important a metric for some users as maximum bit
Newman Page [6]
forwarding rate.
While "connection" describes only a state and not necessarily the While "connection" describes only a state and not necessarily the
transfer of data, concurrency assumes that all existing connections are transfer of data, concurrency assumes that all existing
in fact capable of transferring data. If a data cannot be sent over a connections are in fact capable of transferring data. If a data
connection, that connection should not be counted toward the number of cannot be sent over a connection, that connection should not be
concurrent connections. counted toward the number of concurrent connections.
Measurement units: Measurement units:
Concurrent connections Concurrent connections
Maximum number of concurrent connections Maximum number of concurrent connections
Issues: Issues:
See also: See also:
connections connections
connection establishment rate connection establishment rate
connection overhead connection overhead
3.7 Connection 3.7 Connection
Definition: Definition:
A state in which two hosts, or a host and the DUT/SUT, agree to exchange
data using a known protocol. A state in which two hosts, or a host and the DUT/SUT, agree to
exchange data using a known protocol.
Discussion: Discussion:
A connection is an abstraction describing an agreement between two A connection is an abstraction describing an agreement between two
nodes: One agrees to send data and the other agrees to receive it. nodes: One agrees to send data and the other agrees to receive it.
Connections MAY be TCP sessions, but they don't have to be. Other Connections may be TCP sessions, but they don't have to be. Other
connection-oriented protocols such as ATM also may be used, either connection-oriented protocols such as ATM also may be used, either
instead of or in addition to TCP connections. instead of or in addition to TCP connections.
What constitutes a connection depends on the application. For a "native What constitutes a connection depends on the application. For a
ATM" application like a video stream, connections and virtual circuits "native ATM" application like a video stream, connections and
can be synonymous. For TCP/IP applications on ATM networks (where virtual circuits can be synonymous. For TCP/IP applications on ATM
multiple TCP sessions may ride over a single ATM virtual circuit), the networks (where multiple TCP sessions may ride over a single ATM
virtual circuit), the number of TCP connections is probably the
Newman Page [6] most important consideration.
number of TCP connections is probably the most important consideration. Additionally, in some cases firewalls may handle a mixture of
native TCP and native ATM connections. In this situation, the
wrappers around user data will differ. The most meaningful metric
describes what an end-user will see.
Additionally, in some cases firewalls may handle a mixture of native TCP Data connections describe state, not data transfer. The existence
and native ATM connections. In this situation, the wrappers around user of a connection does not imply that data travels on that
data will differ. The most meaningful metric describes what an end-user connection at any given time, although if data cannot be forwarded
will see. on a previously established connection that connection should not
be considered in any aggregrate connection count (see concurrent
Data connections describe state, not data transfer. The existence of a Newman Page [7]
connection does not imply that data travels on that connection at any connections).
given time, although if data cannot be forwarded on a previously
established connection that connection should not be considered in any
aggregrate connection count (see concurrent connections).
A firewall's architecture dictates where a connection is terminated. In A firewall's architecture dictates where a connection is
the case of proxy-based systems, a connection terminates at the DUT/SUT. terminated. In the case of proxy-based systems, a connection
But firewalls using packet filtering or stateful packet filtering terminates at the DUT/SUT. But firewalls using packet filtering or
designs act only as passthrough devices, in that they reside between two stateful packet filtering designs act only as passthrough devices,
connection endpoints. Regardless of firewall architecture, the number of in that they reside between two connection endpoints. Regardless
data connections is still relevant, since all firewalls perform some of firewall architecture, the number of data connections is still
form of connection maintenance; at the very least, all check connection relevant, since all firewalls perform some form of connection
requests against their rule sets. maintenance; at the very least, all check connection requests
against their rule sets.
Though it seems paradoxical, connectionless protocols such as UDP may Though it seems paradoxical, connectionless protocols such as UDP
also involve connections, at least for the purposes of firewall may also involve connections, at least for the purposes of
performance measurement. For example, one host may send UDP packets to firewall performance measurement. For example, one host may send
another across a firewall. If the destination host is listening on the UDP packets to another across a firewall. If the destination host
correct UDP port, it receives the UDP packets. For the purposes of is listening on the correct UDP port, it receives the UDP packets.
firewall performance measurement, this is considered a connection. For the purposes of firewall performance measurement, this is
Indeed, some firewall implementations dynamically alter their rule sets considered a connection. Indeed, some firewall implementations
to allow such connections. dynamically alter their rule sets to allow such connections.
Measurement units: Measurement units:
Connection establishment rate Connection establishment rate
Concurrent connections Concurrent connections
Maximum number of concurrent connections Maximum number of concurrent connections
Issues: Issues:
proxy-based vs. stateful packet filtering proxy-based vs. stateful packet filtering
TCP/IP vs. ATM TCP/IP vs. ATM
connection-oriented vs. connectionless connection-oriented vs. connectionless
See also: See also:
data source data source
concurrent connections concurrent connections
connection establishment rate connection establishment rate
3.8 Connection establishment rate 3.8 Connection establishment rate
Definition: Definition:
The length of time needed for two hosts, or a host and the DUT/SUT, to
agree to set up a data exchange using a known protocol. The length of time needed for two hosts, or a host and the
DUT/SUT, to agree to set up a data exchange using a known
protocol.
Discussion: Discussion:
Each connection-oriented protocol has its own defined mechanisms for
Newman Page [7] 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 octet of the packet carrying a connection establishment
request on a DUT/SUT interface until transmission of the last
setting up a connection. For purposes of benchmarking firewall Newman Page [8]
performance, this shall be the interval between receipt of the first octet of the last packet of the connection setup traffic headed in
octet of the packet carrying a connection establishment request on a the opposite direction.
DUT/SUT interface until transmission of the last octet of the last
packet of the connection setup traffic headed in the opposite direction.
This definition applies only to connection-oriented protocols such as This definition applies only to connection-oriented protocols such
TCP. For connectionless protocols such as UDP, the notion of connection as TCP. For connectionless protocols such as UDP, the notion of
setup time is not meaningful. connection setup time is not meaningful.
Measurement units:
Metric
Connection establishment rate Connection establishment rate
Issues: Issues:
See also: See also:
concurrent connections concurrent connections
connection connection connection overhead
connection overhead
3.9 Connection overhead 3.9 Connection overhead
Definition: 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 degradation in bit forwarding rate, if any, observed as a
the addition of one connection from a host to the DUT/SUT. 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: 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 The memory cost of connection establishment and maintenance is
improvement as a result of tearing down one connection. 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.
Measurement units: Measurement units:
bit forwarding rate bit forwarding rate
Issues: Issues:
3.10 Data source 3.10 Data source
Definition: Definition:
A station capable of generating traffic to the DUT/SUT. A station capable of generating traffic to the DUT/SUT.
Discussion: 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.
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.
Newman Page [9]
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
Newman Page [8] The term "data source" is deliberately independent of any number
of users. It is useful to think of data sources simply as traffic
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. generators, without any correlation to any given number of users.
See also: See also:
connection connection
3.11 Demilitarized zone (DMZ) 3.11 Demilitarized zone (DMZ)
Definition: Definition:
A network segment or segments located between protected and unprotected
networks. DMZ networks are sometimes called perimeter networks. A network segment or segments located between protected and
unprotected networks. DMZ networks are sometimes called perimeter
networks.
Discussion: Discussion:
As an extra security measure, networks are often designed such that
protected and unprotected segments are never directly connected. As an extra security measure, networks are often designed such
Instead, firewalls (and possibly public resources such as WWW or FTP that protected and unprotected segments are never directly
servers) often reside on the so-called DMZ network. To connect connected. Instead, firewalls (and possibly public resources such
protected, DMZ, and unprotected networks with one device, the device as WWW or FTP servers) often reside on the so-called DMZ network.
MUST have at least three network interfaces. To connect protected, DMZ, and unprotected networks with one
device, the device MUST have at least three network interfaces.
Multiple firewalls MAY bound the DMZ. In this case, the firewalls Multiple firewalls MAY bound the DMZ. In this case, the firewalls
connecting the protected network with the DMZ and the DMZ with the connecting the protected network with the DMZ and the DMZ with the
unprotected network MUST each have at least two network interfaces. unprotected network MUST each have at least two network
interfaces.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
Homed Homed
See also: See also:
unprotected network unprotected network
perimeter network perimeter network
protected network protected network
3.12 Firewall 3.12 Firewall
Definition: Definition:
A device or group of devices that enforces an access control policy
between networks.
Discussion: Newman Page [10]
While there are many different ways to accomplish it, all firewalls do A device or group of devices that enforces an access control
the same thing: control access between networks. policy between networks.
The most common configuration involves a firewall connecting two Discussion:
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 is controlled is deliberately not specified While there are many different ways to accomplish it, all
here. Typically this has been done using network- or transport-layer firewalls do essentially the same thing: control access between
networks.
Newman Page [9] 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.
criteria (such as IP subnet or TCP port number), but there is no reason The criteria by which access is controlled is deliberately not
this must always be so. A growing number of firewalls are controlling specified here. Typically this has been done using network- or
access at the application layer, using user identification as the transport-layer criteria (such as IP subnet or TCP port number),
criterion. And firewalls for ATM networks may control access based on but there is no reason this must always be so. A growing number of
data link-layer criteria. 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.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
DMZ DMZ
tri-homed tri-homed
user user
3.13 Goodput 3.13 Goodput
Definition: 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. 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: 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 Firewalls are generally insensitive to packet loss in the network.
ATM, for example, request different types of retransmissions. Testers As such, measurements of gross bit forwarding rates are not
MUST observe retransmitted data for the protocol in use, and subtract meaningful since (in the case of proxy-based and stateful packet
this quantity from measurements of gross bit forwarding rate. 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.
Newman Page [11]
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.
Measurement unit:
Unit of measurement:
bits per second bits per second
Issues: Issues:
allowed vs. rejected traffic allowed vs. rejected traffic
See also: See also:
allowed traffic allowed traffic
bit forwarding rate bit forwarding rate
rejected traffic rejected traffic
3.14 Homed 3.14 Homed
Definition: Definition:
The number of logical interfaces a DUT/SUT contains. The number of logical interfaces a DUT/SUT contains.
Discussion: Discussion:
Firewalls MUST contain at least two logical interfaces. In network
topologies where a DMZ is used, the firewall contains at least three
interfaces and is said to be tri-homed. Additional interfaces would make
Newman Page [10]
a firewall quad-homed, quint-homed, and so on. Firewalls MUST contain at least two logical interfaces. In network
topologies where a DMZ is used, the firewall 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 It is theoretically possible for a firewall to contain one
interface and multiple logical interfaces. This configuration is physical interface and multiple logical interfaces. This
strongly discouraged for testing purposes because of the difficulty in configuration is strongly discouraged for testing purposes because
verifying that no leakage occurs between protected and unprotected of the difficulty in verifying that no leakage occurs between
segments. protected and unprotected segments.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
tri-homed tri-homed
3.15 Illegal traffic 3.15 Illegal traffic
Definition: Definition:
Packets specified for rejection in the rule set of the DUT/SUT. Packets specified for rejection in the rule set of the DUT/SUT.
Newman Page [12]
Discussion: Discussion:
A buggy or misconfigured firewall may forward packets even though its
rule set specifies that these packets be dropped. Illegal traffic A buggy or misconfigured firewall may forward packets even though
differs from rejected traffic in that it describes all traffic specified its rule set specifies that these packets be dropped. Illegal
for rejection by the rule set, while rejected traffic specifies only traffic differs from rejected traffic in that it describes all
those packets actually dropped by the DUT/SUT. traffic specified for rejection by the rule set, while rejected
traffic specifies only those packets actually dropped by the
DUT/SUT.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
accepted traffic accepted traffic
policy policy
rejected traffic rejected traffic
rule set rule set
3.16 Logging 3.16 Logging
Definition: Definition:
The recording of user requests made to the firewall. The recording of user requests made to the firewall.
Discussion: Discussion:
Firewalls MUST 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 Firewalls MUST log all requests they handle, both allowed and
SHOULD attempt to log equivalent data when comparing different DUT/SUTs. rejected. For many firewall designs, logging requires a
significant amount of processing overhead, especially when complex
rule sets are in use.
Logging MAY take place on systems other than the DUT/SUT. The type and amount of data logged varies by implementation.
Testers SHOULD attempt to log equivalent data when comparing
different DUT/SUTs.
Newman Page [11] Logging MAY take place on systems other than the DUT/SUT.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
rule sets rule sets
See also: See also:
allowed traffic allowed traffic
connection connection
Newman Page [13]
rejected traffic rejected traffic
session
3.17 Network address translation (NAT) 3.17 Network address translation (NAT)
Definition: Definition:
A method of mapping one or more private, reserved IP addresses to one or
more public IP addresses. A function that maps the original IP source and/or destination
addresses of packets arriving at a given interface of the firewall
to a different address or addresses.
Discussion: 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).
The use of private addressing also introduces a security benefit in that Firewalls use NAT to ensure that the IP addresses of a protected
RFC 1918 addresses are not visible to hosts on the public Internet. network are not visible to systems and users on the Internet or
some other untrusted network. This is typically required since
many networks use RFC 1918 reserved addresses.
Some NAT implementations are computationally intensive, and may affect In the interest of conserving the IPv4 address space, RFC 1918
bit forwarding rate. 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).
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.
There are two common methods for NAT: many to one (aggregation)
and one to one mapping. It should be noted that all proxy
firewalls always perform NAT as a function of their architecture,
while, by default, packet filtering firewalls do not. In general
all application and circuit proxy firewalls, by default, perform
NAT as a function of their architecture using the aggregation
method, while stateful packet filtering firewalls do not perform
NAT by default, but can be configured to do so.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
3.18 Packet filtering 3.18 Packet filtering
Definition: Definition:
The process of controlling access by examining packets based on packet
header content.
The process of controlling access by examining packets based on
packet header content.
Newman Page [14]
Discussion: 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- Packet-filtering firewalls forward or deny packets based on
filtering firewall uses a rule set to determine which traffic should be information in each packet's header, such as IP address or TCP
forwarded and which should be blocked. port number. A packet- filtering firewall uses a rule set to
determine which traffic should be forwarded and which should be
blocked.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
Newman Page [12] static vs. stateful packet filtering
static versus stateful packet filtering
See also: See also:
application proxy application proxy
circuit proxy circuit proxy
proxy proxy
rule set rule set
stateful packet filtering stateful packet filtering
3.19 Perimeter network 3.19 Perimeter network
Definition: Definition:
A network segment or segments located between protected and unprotected
networks. Perimeter networks are often called DMZ networks. A network segment or segments located between protected and
unprotected networks. Perimeter networks are often called DMZ
networks.
Discussion: Discussion:
See the definition of DMZ for a discussion. See the definition of DMZ for a discussion.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
Tri-homed Tri-homed
See also: See also:
demilitarized zone (DMZ) demilitarized zone (DMZ)
unprotected network unprotected network
protected network protected network
3.20 Policy 3.20 Policy
Definition: Definition:
skipping to change at line 713 skipping to change at line 832
Tri-homed Tri-homed
See also: See also:
demilitarized zone (DMZ) demilitarized zone (DMZ)
unprotected network unprotected network
protected network protected network
3.20 Policy 3.20 Policy
Definition: Definition:
A document defining acceptable access to protected, DMZ, and unprotected
networks. A document defining acceptable access to protected, DMZ, and
Newman Page [15]
unprotected networks.
Discussion: 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 Security policies generally do not spell out specific
implemented in the DUT/SUT. configurations for firewalls; rather, they set general guidelines
for what is and is not acceptable network access.
The actual mechanism for enforcing the access policies is usually
the rule set implemented in the DUT/SUT.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
rule set rule set
3.21 Protected network 3.21 Protected network
Definition: Definition:
Newman Page [13]
A network segment or segments to which access is controlled by the A network segment or segments to which access is controlled by the
DUT/SUT. DUT/SUT.
Discussion: Discussion:
Firewalls 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
unprotected network, or both.
Protected networks are often called "internal networks." That term is Firewalls are intended to prevent unauthorized access either to or
not used here because firewalls increasingly are deployed within an from the protected network. Depending on the configuration
organization, where all segments are by definition internal. 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 unprotected network, or both.
Protected networks are often called "internal networks." That term
is not used here because firewalls increasingly are deployed
within an organization, where all segments are by definition
internal. It is also possible for a firewall to protected
multiple, but different protected networks from each other.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
demilitarized zone (DMZ) demilitarized zone (DMZ)
unprotected network unprotected network
policy policy
rule set rule set
Newman Page [16]
unprotected network unprotected network
3.22 Proxy 3.22 Proxy
Definition: Definition:
A request for a connection made on behalf of a host. A request for a connection made on behalf of a host.
Discussion: Discussion:
Proxy-based firewalls do not allow direct connections between hosts.
Instead, two connections are established: one between the client host
and the DUT/SUT, and another between the DUT/SUT and server host.
As with packet-filtering firewalls, proxy-based devices use a rule set Proxy-based firewalls do not allow direct connections between
to determine which traffic should be forwarded and which should be hosts. Instead, two connections are established: one between the
rejected. client host and the DUT/SUT, and another between the DUT/SUT and
server host.
There are two types of proxies: application proxies and circuit proxies. As with packet-filtering firewalls, proxy-based devices use a rule
set to determine which traffic should be forwarded and which
should be rejected.
There are two types of proxies: application proxies and circuit
proxies.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
application application
See also: See also:
application proxy
circuit proxy application
proxy circuit
proxy
packet filtering packet filtering
stateful packet filtering stateful packet filtering
Newman Page [14]
3.23 Rejected traffic 3.23 Rejected traffic
Definition: Definition:
Packets dropped as a result of the rule set of the DUT/SUT. Packets dropped as a result of the rule set of the DUT/SUT.
Discussion: Discussion:
Firewalls MUST reject any traffic not explicitly permitted in the rule
set. Dropped packets MUST NOT be included in calculating the bit Firewalls MUST reject any traffic not explicitly permitted in the
forwarding rate or maximum bit forwarding rate of the DUT/SUT. rule set. Dropped packets MUST NOT be included in calculating the
bit forwarding rate or maximum bit forwarding rate of the DUT/SUT.
Measurement units: Measurement units:
not applicable not applicable
Newman Page [17]
Issues: Issues:
See also: See also:
policy policy
rule set rule set
3.24 Rule set 3.24 Rule set
Definition: Definition:
The collection of access control rules that determines which packets the
DUT/SUT will forward and which it will reject. The collection of access control rules that determines which
packets the DUT/SUT will forward and which it will reject.
Discussion: Discussion:
Rule sets control access to and from the network interfaces of the 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 DUT/SUT. By definition, rule sets MUST NOT apply equally to all
interfaces; otherwise there would be no need for the firewall. network interfaces; otherwise there would be no need for the
Therefore, a specific rule set MUST be applied to each network interface firewall. Therefore, a specific rule set MUST be applied to each
in the DUT/SUT. network interface in the DUT/SUT.
The order of rules within the rule set is critical. Firewalls generally The order of rules within the rule set is critical. Firewalls
scan rule sets in a "top down" fashion, which is to say that the device generally scan rule sets in a "top down" fashion, which is to say
compares each packet received with each rule in the rule set until it that the device compares each packet received with each rule in
finds a rule that applies to the packet. Once the device finds an the rule set until it finds a rule that applies to the packet.
applicable rule, it applies the actions defined in that rule (such as Once the device finds an applicable rule, it applies the actions
forwarding or rejecting the packet) and ignores all subsequent rules. defined in that rule (such as forwarding or rejecting the packet)
For testing purposes, the rule set MUST conclude with a rule denying all and ignores all subsequent rules. For testing purposes, the rule
access. set MUST conclude with a rule denying all access.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
demilitarized zone (DMZ) demilitarized zone (DMZ)
policy policy
protected network protected network
rejected traffic rejected traffic
unprotected network unprotected network
3.25 Stateful packet filtering 3.25 Stateful packet filtering
Newman Page [15]
Definition: Definition:
The process of forwarding or rejecting traffic based on the contents of
a state table maintained by a firewall. The process of forwarding or rejecting traffic based on the
contents of a state table maintained by a firewall.
Discussion: Discussion:
Packet filtering and proxy firewalls are essentially static, in that
they always forward or reject packets based on the contents of the rule
set.
In contrast, devices using stateful packet filtering will only forward Newman Page [18]
packets if they correspond with state information maintained by the Stateful packet filtering ensures that packets associated with an
device about each session. For example, a stateful packet filtering already established (and authorized) connection are allowed to be
device will reject a packet on port 20 (ftp-data) if no session has been forwarded through the firewall. This differs from a simple packet
established over the ftp control port (usually port 21). filter firewall that would allow any packets through regardless of
the state of that connection. For example, a stateful packet
filtering device will reject a packet on port 20 (ftp-data) if no
session has been established over the ftp control port (usually
port 21).
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
dynamic proxy
application proxy
circuit proxy
packet filter packet filter
proxy proxy
3.26 Tri-homed 3.26 Tri-homed
Definition: Definition:
A firewall with three network interfaces. A firewall with three network interfaces.
Discussion: Discussion:
Tri-homed firewalls connect three network segments with different Tri-homed firewalls connect three network segments with different
network addresses. Typically, these would be protected, DMZ, and network addresses. Typically, these would be protected, DMZ, and
unprotected segments. unprotected segments.
A tri-homed firewall may offer some security advantages over firewalls A tri-homed firewall may offer some security advantages over
with two interfaces. An attacker on an unprotected network may firewalls with two interfaces. An attacker on an unprotected
compromise hosts on the DMZ but still not reach any hosts on the network may compromise hosts on the DMZ but still not reach any
protected network. hosts on the protected network.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
Usually the differentiator between one segment and another is its IP
address. However, firewalls may connect different networks of other Usually the differentiator between one segment and another is its
types, such as ATM or Netware segments. IP address. However, firewalls may connect different networks of
other types, such as ATM or Netware segments.
See also: See also:
homed homed
3.27 Unprotected network 3.27 Unprotected network
Newman Page [16] Newman Page [19]
Definition: Definition:
A network segment or segments to which access is not controlled by the
DUT/SUT. A network segment or segments to which access is not controlled by
the DUT/SUT.
Discussion: Discussion:
Firewalls are deployed between protected and unprotected segments. The
unprotected network is not protected by the DUT/SUT. Firewalls are deployed between protected and unprotected segments.
The unprotected network is not protected by the DUT/SUT.
Note that a DUT/SUT's policy MAY specify hosts on an unprotected Note that a DUT/SUT's policy MAY specify hosts on an unprotected
network. For example, a user on a protected network may be permitted to network. For example, a user on a protected network may be
access an FTP server on an unprotected network. But the DUT/SUT cannot permitted to access an FTP server on an unprotected network. But
control access between hosts on the unprotected network. the DUT/SUT cannot control access between hosts on the unprotected
network.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
demilitarized zone (DMZ) demilitarized zone (DMZ)
policy policy
protected network protected network
rule set rule set
3.28 User 3.28 User
Definition: Definition:
A person or process requesting access to resources protected by the
DUT/SUT. A person or process requesting access to resources protected by
the DUT/SUT.
Discussion: Discussion:
"User" is a problematic term in the context of firewall performance
testing, for several reasons. First, a user may in fact be a process or
processes 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 user.
For these reasons, we prefer not to measure DUT/SUT performance in terms "User" is a problematic term in the context of firewall
of users supported. Instead, we describe performance in terms of maximum performance testing, for several reasons. First, a user may in
bit forwarding rate and maximum number of sessions sustained. Further, fact be a process or processes requesting services through the
we use the term "data source" rather than user to describe the traffic DUT/SUT. Second, different "user" requests may require radically
generator(s). 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 user.
For these reasons, it's probably not a good idea to measure
DUT/SUT performance in terms of users supported. The only
exception is in cases where traffic patterns are well understood
and constant--conditions that unfortunately don't exist in many
networks. Instead, it's preferable to describe performance in
terms of maximum bit forwarding rate and maximum number of
connections sustained. It's also preferable to use the term "data
Newman Page [20]
source" rather than "user" to describe the traffic generator(s) to
avoid any confusion with actual user data profiles.
Measurement units: Measurement units:
not applicable not applicable
Issues: Issues:
See also: See also:
data source data source
4. Security considerations 4. Security considerations
Newman Page [17] The primary goal of this memo is to describe terms used in
benchmarking firewall performance. However, readers should be aware
The primary goal of this memo is to describe terms used in benchmarking that there is some overlap between performance and security issues.
firewall performance. However, readers should be aware that there is Specifically, the optimal configuration for firewall performance may
some overlap between performance and security issues. Specifically, the not be the most secure, and vice-versa.
optimal configuration for firewall performance may not be the most
secure, and vice-versa.
Further, certain forms of attack may degrade performance. One common Further, certain forms of attack may degrade performance. One common
form of denial-of-service (DoS) attack bombards a firewall with so much form of denial-of-service (DoS) attack bombards a firewall with so
rejected traffic that it cannot forward allowed traffic. DoS attacks do much rejected traffic that it cannot forward allowed traffic. DoS
not always involve heavy loads; by definition, DoS describes any state attacks do not always involve heavy loads; DoS describes any state in
in which a firewall is offered rejected traffic that prohibits it from which a firewall is offered rejected traffic that prohibits it from
forwarding some or all allowed traffic. Even a small amount of traffic-- forwarding some or all allowed traffic. Even a small amount of
such as the recent Teardrop2 attack involving a few packet fragments-- traffic-- such as the recent Teardrop2 attack involving a few packet
may significantly degrade firewall performance, or stop the firewall fragments-- may significantly degrade firewall performance, or stop
altogether. Further, the safeguards in firewalls to guard against such the firewall altogether. Further, the safeguards in firewalls to
attacks may have have a significant negative impact on performance. guard against such attacks may have a significant negative impact on
performance.
Since the library of attacks is constantly expanding, no attempt is made Since the library of attacks is constantly expanding, no attempt is
here to define specific attacks that may affect performance. made here to define specific attacks that may affect performance.
Nonetheless, any reasonable performance benchmark must take safeguards Nonetheless, any reasonable performance benchmark must take
against such attacks into consideration. Specifically, the same safeguards against such attacks into consideration. Specifically, the
safeguards must be in place when comparing performance of different same safeguards must be in place when comparing performance of
firewall implementations. different firewall implementations.
5. References 5. References
Bradner, S., editor. "Benchmarking Terminology for Network Bradner, S., editor. "Benchmarking Terminology for Network
Interconnection Devices." RFC 1242. Interconnection Devices." RFC 1242.
Bradner, S., and McQuaid, J. "Benchmarking Methodology for Network Bradner, S., and McQuaid, J. "Benchmarking Methodology for Network
Interconnect Devices." RFC 1944. Interconnect Devices." RFC 1944.
Mandeville, R. "Benchmarking Terminology for LAN Switching Devices." RFC Mandeville, R. "Benchmarking Terminology for LAN Switching Devices."
2285. RFC 2285.
Rekhter, Y., et al. "Address Allocation for Private Internets." RFC Rekhter, Y., et al. "Address Allocation for Private Internets." RFC
1918. 1918.
Newman Page [21]
6. Acknowledgments 6. Acknowledgments
The author wishes to thank the IETF Benchmarking Working Group for The editor wishes to thank the IETF Benchmarking Working Group for
agreeing to review this document. Several other persons offered valuable agreeing to review this document. Many persons offered valuable
contributions and critiques during this project: Ted Doty (Internet contributions and critiques during this project: Ted Doty (Internet
Security Systems), Kevin Dubray (Bay Networks), Helen Holzbaur (NSTL), Security Systems), Kevin Dubray (Bay Networks), Helen Holzbaur
Jim Hurd (NSTL), Robert Mandeville (European Network Laboratories), (NSTL), Jim Hurd (NSTL), Dale Lancaster (Axent Technologies), Robert
Brent Melson (NSTL), Steve Platt (NSTL), Marcus Ranum (Network Flight Mandeville (European Network Laboratories), Brent Melson (NSTL),
Recorder Inc.), Greg Shannon (Ascend Communications), Christoph Schuba Steve Platt (NSTL), Marcus Ranum (Network Flight Recorder Inc.), Greg
(Sun Microsystems), Rick Siebenaler (Cyberguard), and Greg Smith (Check Shannon (Ascend Communications), Christoph Schuba (Sun Microsystems),
Point Software Technologies). Rick Siebenaler (Cyberguard), and Greg Smith (Check Point Software
Technologies).
Newman Page [18]
7. Contact information 7. Contact information
David Newman David Newman
Data Communications magazine Data Communications magazine
1221 Avenue of the Americas, 41st Floor 1221 Avenue of the Americas, 41st floor
New York, NY 10020 New York, NY 10020 USA
USA
212-512-6182 voice 212-512-6182 voice
212-512-6833 fax 212-512-6833 fax
dnewman@data.com dnewman@data.com
Newman Page [19] Newman Page [22]
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