IPFIX Working Group EDITORS: K.C. Norseth
Internet Draft Consultant
Expiration Date: October 2002 Ganesh Sadasivan
Cisco Systems, Inc.
April 2002
Architecture Model for IP Flow Information Export
draft-ietf-ipfix-architecture-01.txt
Status of this Memo
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all provisions of Section 10 of RFC2026.
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Abstract
This memo defines the architecture, for the export of measured IP
flow information out of an IPFIX device to a collector, per the
requirements defined in [2].
Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119.
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Table of Contents
1 Introduction ........................................... 3
2 Scope .................................................. 3
3 Terminology ............................................ 3
4 IPFIX reference Model .................................. 7
4.1 IPFIX protocol ......................................... 10
4.2 Export Process ......................................... 10
4.3 Observation Domain ..................................... 11
4.4 Metering Process Functions ............................. 11
4.4.1 Flow Classification .................................... 11
4.4.2 Selection Criteria Of Packets .......................... 12
4.4.3 Function on properties that determines a flow type (Fi) ....12
4.4.4 Sampling packets on a flow type (Si) ................... 12
4.5 Selection Criteria of flows for export ................. 13
4.6 Collector .............................................. 13
4.7 Applications ........................................... 14
5 IPFIX Protocol ......................................... 14
5.1 Selection Criteria for IPFIX Protocol .................. 14
5.1.1 Common for IPFIX Device and Collector .................. 14
5.1.2 IPFIX Protocol on IPFIX Device (At Export Process) ..... 14
5.1.3 Intellectual Property Rights ........................... 15
5.1.4 IPFIX Protocol on Collector ............................ 15
5.2 Export Models .......................................... 15
5.2.1 Export Model with Reliable Control Connection .......... 15
5.3 Collector Crash Detection and Recovery ................. 16
5.3.1 Export Model with Reliable Control Connection .......... 16
5.4 Collector Redundancy ................................... 16
6 Security Consideration ................................. 17
6.1 Data security .......................................... 17
6.1.1 No security ............................................ 17
6.1.2 Authentication only .................................... 17
6.1.3 Encryption ............................................. 18
6.2 IPFIX end point authentication ......................... 18
6.3 Denial of service (DoS) attack prevention .............. 19
6.3.1 Network under attack ................................... 19
6.3.2 Generic DoS attack on the IPFIX system ................. 19
6.3.3 IPFIX Specific DoS attack .............................. 19
7 Flow Expiration ........................................ 19
8 IANA Consideration ..................................... 20
9 References ............................................. 20
10 Acknowledgements ....................................... 20
11 Author's Addresses ..................................... 21
12 Full Copyright Statement ............................... 22
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1. Introduction
There are several applications e.g., Usage-based Accounting, Traffic
Profiling, Traffic engineering, Attack/Intrusion Detection, QoS
Monitoring, that require require flow-based IP traffic measurements.
It is hence important to have a standard way of exporting information
related to IP flows. This document defines architecture for IP
traffic flow monitoring, measuring and exporting. It provides a
high-level description of the key components and their functions.
2. Scope
This document defines architecture for IPFIX. The main objective of
this document is to:
* Describe the key architectural components of IPFIX.
* Define the architectural requirements, e.g., Recovery, Security,
etc for the IPFIX framework.
* Define the criteria to select the IPFIX Protocol.
* Specify the control/data message formats and handshaking details
to pass the IP flow information.
3. Terminology
* IP Traffic Flow or Flow:
A flow is defined as a set of packets passing an observation
point in the network during a certain time interval. All packets
belonging to a particular flow have a set of common properties
derived from the data contained in the packet and from the packet
treatment at the observation point.
In this draft we define the flow more specifically. A flow is
defined as a set of packets passing an observation point in the
network during a certain time interval. All packets belonging to
a particular flow have a set of common properties. Each property
is defined as the result of applying a function to the values of:
Each property is defined as the result of applying a function to
the values of:
1. One or more of packet header fields (eg. destination IP
address)
2. One or more properties of the packet itself (eg. packet
length)
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3. One or more of fields derived from packet treatment (eg. AS
number)
A packet is defined to belong to a flow if it matches all the
defined properties of the flow. Each of the fields from 1., 2.
and 3. are referred to as flow keys. Though a flow could match a
general application-level end-to-end stream, its definition is
not restricted to this alone. The above definition covers a broad
range from a flow containing all packets observed on a set of
observation points to a flow consisting of just a single packet
between two applications with a specific sequence number observed
at a single observation point. Some examples of flows are listed
below:
Example 1: To create flows, we define the different fields to
distinguish flows. The different combination of the field values
creates unique flows. If the keys are defined as {source IP
address, destination IP address, TOS}, then all of these are
different flows.
1. {192.1.40.1, 171.6.23.5, 4}
2. {192.1.40.23, 171.6.23.67, 4}
3. {192.1.40.23, 171.6.23.67, 2}
4. {198.20.9.200, 171.6.23.67, 4}
Example 2: To create flows, we can apply a match function to all
the packets that pass through an observation point, in order to
aggregate some values. This could be done by defining the keys as
{source IP address, destination IP address, TOS} like in the
example 1, and applying the function which masks the least
significant 8 bits of the source IP address and destination IP
address (i.e. the resultant is a /24 address). The 4 flows from
example 1 would now be aggregated into 3 flows, by merging the
flows 1. and 2. into a single flow.
1. {192.1.40.0/24, 171.6.23.0/24, 4}
2. {192.1.40.0/24, 171.6.23.0/24, 2}
3. {198.20.9.0/24, 171.6.23.0/24, 4}
Example 3: To create flows, we can filter some field values on
all packets that pass the observation point, in order to select
only certain flows. The filter is defined by choosing fixed
values for specific fields from the packet.
All the packets that go from a customer network 192.1.40.0/24 to
another customer network 171.6.23.0/24 with TOS value of 4 define
a flow. All other combinations don't define a flow and are not
taken into account. The 3 flows from example 2 would now be
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reduced to 1 flow, by filtering away the second and the third
flow. {192.1.40.0/24, 171.6.23.0/24, 4}.
The above example can be thought of as a function F takes as
input {source IP address, destination IP address, TOS}. The
function selects only the packets which satisfy all the 3
conditions which are:
* mask the least significant 8 bits of source IP address,
compare against 192.1.40.0.
* mask the least significant 8 bits of destination IP address,
compare against 171.6.23.0.
* tos value equal to 4.
Depending on the values of {source IP address, destination IP
address, TOS} of the different observed packets, the metering
process function F would choose/filter/aggregate different sets
of packets, which would create different flows. In other words,
based on various combination of values of {source IP address,
destination IP address, TOS}, F(source IP address, destination IP
address, TOS) would result in the definition of one or more
flows. The function F is referred to as Flow Type.
* Flow Key:
Each of the field which belongs to
1. Packet header (eg. destination IP address)
2. Property of the packet itself (eg. packet length)
3. Derived from packet treatment (eg. AS number)
which is used to define a flow is termed as flow key.
* Flow Type:
A function F which would take input as a set of flow keys and the
output would be one or more flows depending on the combination of
values for the set of flow keys.
* Flow Record:
A flow record contains information about a specific flow that was
metered at an observation point. A flow record contains measured
properties of the flow (e.g. the total number of bytes of all
packets of the flow) and usually characteristic properties of the
flow (e.g. source IP address).
* Export Process:
The process of sending flow records to one or more collectors.
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* IPFIX Device:
A device hosting at least an observation point, a metering
process and a export process. Typically, corresponding
observation point(s), metering process(es), and exporter
process(es) are co-located at this device, for example, at a
router.
* Collector:
The collector receives flow records from one or more exporters.
The collector might process or store received flow record, but
these actions are out of the scope of this document.
* Observation Point:
The observation point is a location in the network where IP
packets can be observed. Examples are, a line to which a probe is
attached, a shared medium, such as an Ethernet-based LAN, a
single port of a router, or a set of interfaces (physical or
logical) of a router.
* Metering Process:
The metering process generates flow records. Input to the process
are IP packets observed in an observation point. The metering
process consists of a set of functions that includes packet
header capturing, timestamping, sampling, classifying, and
maintaining flow records.
* Observation Domain:
The set of observation points which is the largest aggregatable
set of flow information at the IPFIX Device is termed as an
observation domain. The observation domain presents itself a
unique ID to the collector for identifying the export packets
generated by it. One or more Observation Domains can interface
with the same export process. Example: The observation domain
could be a router line-card, composed of several interfaces with
each interface being an observation point.
* Template:
Templates is a set of ordered pairs (eg. <type,length>, TLV),
used to completely identify the structure and semantics of a
particular information that needs to be communicated from the
IPFIX Device to the collector. Each template is uniquely
identifiable by some means (eg. by using a Template ID).
* Control Stream, Data Stream:
The information that needs to be exported from the IPFIX device
can be classified into the following categories:
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- Control Information :
This includes the flow type definition, selection criteria
for packets within the flow. This is also called as Control
Stream. This stream carries all the information for the
end-points to understand the IPFIX protocol and specifically
for the receiver to understand and interpret the data stream
send by the sender.
- Flow record :
This includes data records corresponding to the information
on various observed flows at each of the observation
point.This is also called as Data Stream.
The definitions in this section is intended be identical with that in
the IPFIX data model [3] and in the event of a discrepancy, the
definition specified in this document supercedes the one defined in
the latter.
4. IPFIX reference Model
The figure below shows the reference model for IPFIX. This figure
covers the various possible scenarios that can exist in an IPFIX
system.
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+----------------+ +----------------+
|[*Application 1]| ..|[*Application n]|
+--------+-------+ +-------+--------+
^ ^
~ ~
+~~~~~~~~~~+~~~~~~~~+
!
v
+---------------------+ +------------------+
|IPFIX Device(1) | | Collector(1) |
|[Export Process] |<--------------->| |
| | | |
+---------------------+ +------------------+
.... ....
+----------------------+ +------------------+
|IPFIX Device(i) | | Collector(j) |
|[Obsv Point(s)] |<-------------->| [*Application(s)]|
|[Metering Process(es)]| +---->| |
|[Export Process] | | +------------------+
+----------------------+ .
.... . ....
+----------------------+ | +------------------+
|IPFIX Device(m) | | | Collector(n) |
|[Obsv Point(s)] |<---------+---->| [*Application(s)]|
|[Metering Process(es)]| | |
|[Export Process] | +------------------+
+----------------------+
The various functional components are indicated within []. The
functional components within [*] are not part of the IPFIX framework.
The interfaces shown by "<-->" are defined by the the IPFIX framework
and those shown by "<~~>" are not.
The figure below shows a typical IPFIX device.
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+---------------------------------------------------+
| IPFIX Device |
| +---------------------------------------+ +-----+ |
| | Observation Domain 1 | | e | |
| | +------------------------+ (*) | | | |
| | | Selection Criteria for +----+---------> x | |
| | | Flow export | | | | | |
| | +------------------------+ | | | p | |
| | ^ ^ | | | | |
| | |(*) | (*) | | | o | |
| | | | | | | | |
| | +---......--+------------+ | | r | |
| | | | | | | |
| | +----+----+ +----+----+ | | t | |
| | |Metering | |Metering | | | | |
| | |Process 1| |Process N| | | | |
| | |(Packet | |(Packet | | | | |
| | | Level) | | Level) | | | | |
| | +---------+ +---------+ | | | |
| | ^ ^ | | | |
| | | | | | | |
| | +-----+------+ +-----+------+| | | |
| | |Obsv Point 1| ... |Obsv Point M|| | | |
| | +------------+ +------------+| | | |
| +---------------------------------------+ | | |export
| .... | ------>
| +---------------------------------------+ | P | |towards
| | Observation Domain K | | | |the
| | +------------------------+ (*) | | r | |collector(s)
| | | Selection Criteria for +----+---------> | |
| | | Flow export | | | | o | |
| | +------------------------+ | | | | |
| | ^ ^ | | | c | |
| | |(*) | (*) | | | | |
| | | | | | | e | |
| | +---......--+------------+ | | | |
| | | | | | s | |
| | +----+----+ +----+----+ | | | |
| | |Metering | |Metering | | | s | |
| | |Process 1| |Process N| | | | |
| | +---------+ +---------+ | | | |
| | ^ ^ | | | |
| | | | | | | |
| | +-----+------+ +-----+------+| | | |
| | |Obsv Point 1| ... |Obsv Point M|| | | |
| | +------------+ +------------+| | | |
| +---------------------------------------+ +-----+ |
+---------------------------------------------------+
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In this figure the functional blocks are shown in rectangular boxes.
The interface shown by (*) is applicable only if the optional
metering process at the flow level is present. Otherwise the metering
process(es) at the packet level interfaces directly with the
exporting function. Note that in case of multiple observation
domains, a unique ID per observation domain must be transmitted as a
parameters to the exporting function.
4.1. IPFIX protocol
At the IPFIX device, the protocol functionality may be split between
observation domain and export process.
At a high level, IPFIX protocol at the IPFIX device does the
following:
1. Encode the control information into templates.
2. Encode the flows observed at the observation points into flow
records.
3. Packetize the flow record and/or control information into export
packets based on the export policies.
4. Use the underlying transport layer to send the export packets to
the collector.
At a high level, IPFIX protocol at the collector is responsible for
the following:
1. Receive and store the control information.
2. Decode and store the flow records using the control information.
4.2. Export Process
The Export Process is the functional block that interacts with
observation domain(s) on one side and collector(s) on the other side.
The typical functions of an export process may include:
* Accept control/data streams from one or more observation domains
and separate them into separate export packet streams based on
observation domain.
* Run the part of the IPFIX protocol which deals with packetization
and transport of flow records/control information with the
collector. This involves:
- Gather flow records from the metering process(es) and export
them towards the collector(s), using the data stream.
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- Export the control information regarding the flow and
metering process(es) towards the collector(s), using the
control stream.
* Optionally monitor the status of the collector and execute a fail
over in case of problem.
4.3. Observation Domain
The Observation Domain is the functional block, which MUST manage the
flows generated from all the valid {Observation Point, Metering
Process} combination defined within itself. The typical functions of
an Observation Domain may include:
* Encode the flow records and send them to the export process.
* Encode the control information into templates and send them to
the export process.
* Decide which flow records/control information to export using
rules based on time, thresholds, configuration events etc.
* Aggregate flow records generated by one or more metering
processes.
* Flow record maintenance which may include creating new records,
updating existing ones, computing flow statistics, deriving
further flow properties, adding non-flow specific information (in
some cases fields like AS numbers) detecting flow expiration,
passing flows record to the exporting process, and deleting flow
records.
* May perform appropriate middle-box functions to translate the
flow information.
4.4. Metering Process Functions
4.4.1. Flow Classification
The collector MUST be able to map the flow record to the
corresponding property types defined by the flow type. In addition
the collector, when it receives the flow records, MAY need the
following interpreting the flow records further:
a. Observation Point.
b. Selection Criteria of Packets
A flow record can be better analyzed if the Observation Point from
which it is measured is known. As such it is recommended that the
flow record carry the Observation Point information along with the
flow records when exported. In cases where there is a single
observation point or where the observation point information is not
relevant, the exporter MAY choose not to add this to the flow
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records.
4.4.2. Selection Criteria Of Packets
The measurement device MAY define rules so that only certain packets
within a flow can be chosen for measurement at an observation point.
This MAY be done by one of the two types of methods defined below or
a combination of them. A combination of each of these ways can be
adopted to select the packets .i.e. one can define a set of methods
{F1, S1, F2, S2, S3} executed in certain sequence at an observation
point to collect flows of a particular type.
4.4.3. Function on properties that determines a flow type (Fi)
Packets that satisfy a function on the fields defined by the packet
header fields or fields obtained while doing the packet processing or
the properties of the packet itself.
Example: Mask/Match of the fields that define a filter. The filter
may be defined as {Protocol == TCP, Destination Port between 80 and
120}.
Multiple such filters could be used in any sequence to select
packets.
4.4.4. Sampling packets on a flow type (Si)
Packets that satisfy the sampling criteria for this flow type.
Example: Sample every 100th packet that was received at an
observation point and collect the flow information for a particular
flow type. choosing all the packets is a special case where sampling
rate is 1:1.
The figure below shows the operations which MAY be applied as part of
a typical metering process.
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packet header capturing
|
timestamping
|
v
+----->+
| |
| sampling Si (1:1 in case of no sampling)
| |
| classifying Fi (NULL when No criteria)
| |
+------+
|
|
v
Flows
4.5. Selection Criteria of flows for export
There MAY be additional rules defined within the observation domain
so that only certain flows records are picked up for export. This MAY
be done by either one or a combination of Si, Fi.
Example: The flow records which meet the following selection
criteria are only exported.
1. All flow records whose destination IP address matches
{20.3.1.5}.
2. Every other (.i.e. sampling rate 1 in 2) flow record whose
destination IP address matches {160.0.1.30}.
4.6. Collector
Collector is a subsystem that interacts with one or more IPFIX
devices. The functions of the collector MAY include:
* Identifying, accepting and decoding export packets from different
{Export Process, Observation Domain} pairs .
* Running the IPFIX protocol.
* Storing the control information and flow records received from
IPFIX device.
* Notifying the IPFIX device its status and problems.
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4.7. Applications
Applications that use the information collected by IPFIX may be
Billing, Intrusion Detection sub-systems, etc. These applications may
be an integral part of the collector or collocated to the collector.
The way by which these applications interface with IPFIX system to
get the desired information is out of this document's scope.
5. IPFIX Protocol
5.1. Selection Criteria for IPFIX Protocol
There are existing standard practices in the area of flow export like
Netflow, CRANE, LFAP etc. The charter mentions to choose the the
protocol among these existing practices that fits the IPFIX
requirements the most. There may be additions or modifications made
to the chosen protocol to fit it exactly into the IPFIX architecture.
The following is the list of criteria that the candidate protocol
SHOULD meet in order to be the qualified into the IPFIX architecture.
This is based on the requirements specified in the requirement
document [2].
5.1.1. Common for IPFIX Device and Collector
1. Transparency over transport protocol. Ability to operate over a
congestion aware transport like TCP or SCTP.
2. Transparency over any underlying security protocols.
3. The protocol SHOULD be based on a flexible data model based on
templates.
4. The protocol SHOULD be based on a extensible information model.
5.1.2. IPFIX Protocol on IPFIX Device (At Export Process)
1. Ability to detect loss of connectivity with the collector and
trigger the appropriate action (eg. a switch over to an
alternate collector.)
2. Optionally export flow records to multiple collectors.
3. Monitor control information/flow record export, detect any
overload in the process of exporting.
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5.1.3. Intellectual Property Rights
The protocol must abide by the intellectual property rights as
defined in rfc: 2026. Specifically section: 10.3.1. All
Contributions. If the protocol does not abide by this, it will not
be considered.
5.1.4. IPFIX Protocol on Collector
1. Monitor the reception of export packets from IPFIX device.
2. Optionally notify the status and overload conditions to the
IPFIX device.
Once the selection is made from the set of candidate protocols, this
section would be replaced by the chosen protocol.
5.2. Export Models
5.2.1. Export Model with Reliable Control Connection
As mentioned in the selection criteria, the control and data stream
MUST be transported over a congestion-aware transport protocol. If
the network in which the IPFIX device and collector are located does
not guarantee reliability, at least the control stream SHOULD be
exported over a reliable transport. There could be network security
concerns between IPFIX device and collector. To avoid re-inventing
the wheel, and to reduce the complexity of flow export protocol, one
or a combination of the following methods MAY be adopted as a
solution to achieve security :
* IP Authentication Header MAY be used when the threat environment
requires stronger integrity protections, but does not require
confidentiality.
* IP Encapsulating Security Payload (ESP) MAY be used to provide
confidentiality and integrity.
* If the transport protocol used is TCP, optionally TCP MD5
signature option MAY be used to protect against spoofed TCP
segments.
* If the transport protocol used is TCP, optionally TLS MAY be used
to add integrity, authenticity and confidentiality.
The data stream MAY be exported over an reliable or unreliable
transport protocol.
As explained above the transport connection (in the case of a
connection oriented protocol) is pre-setup between the IPFIX device
and the collector. Once connected, the collector side receives the
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control information and uses this information to interpret the flow
records. The IPFIX device SHOULD set the keepalive (eg. keepalive
timeout in the case of TCP; the HEARTBEAT interval in the case of
SCTP; IPFIX protocol level Keepalive if any) to a sufficiently low
value so that it can quickly detect a collector crash.
5.3. Collector Crash Detection and Recovery
5.3.1. Export Model with Reliable Control Connection
The collector crash is detected at the IPFIX device by the break in
control connection (depending on the transport protocol the
connection timeout mechanisms differ). On detecting a Keepalive
timeout, the IPFIX device SHOULD stop sending the flow export data to
the collector and try reconnecting the transport connection. This is
valid for a single collector scenario. If there are multiple
collectors for the same IPFIX device, the IPFIX device opens control
connections to each of the collectors. But data gets sent only to
one of the collectors which is chosen as the primary. There could be
one or more collectors configured as secondary and a priority
assigned to them. The primary collector crash is detected at the
IPFIX device by the break in control connection (depending on the
transport protocol the connection timeout mechanisms differ). On
detecting loss of connectivity, the IPFIX device opens data stream
with the secondary collector of the next highest priority. This
collector now becomes the primary. The maximum export data loss would
be the amount of data exported in the time between when the loss of
connectivity to the collector happened, and the time at which this
was detected by the IPFIX device.
5.4. Collector Redundancy
Since IPFIX protocol requires a congestion-aware transport, achieving
redundancy using multicast is not an option. Multiple <control
stream, data stream> pairs could be setup, each to a different
collector from the same IPFIX device. The control and data
information are then replicated on each of the control stream and
data stream.
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6. Security Consideration
IP flow information can be used for various purposes, such as usage
accounting, traffic profiling, traffic engineering, and intrusion
detection. For each application, the security requirement may differ
significantly from one to another. To be able to satisfy the security
needs of various IPFIX users, the architecture of IPFIX MUST provide
different levels of security protection.
6.1. Data security
IPFIX data consists of control stream and data stream generated by
the IPFIX device.
The IPFIX data may exist in both the IPFIX device and the collector.
In addition, the data is also transferred on the wire from the
exporter to the collector when it is reported. To provide security,
the data SHOULD be protected from adversary.
The protection of IPFIX data within the end system (IPFIX device and
collector) is out of the scope. It is assumed that the end system
operator will provide adequate security for the IPFIX data.
The IPFIX architecture MUST allow different levels of protection to
the IPFIX data on the wire. Where ever security functions are
required it is recommended to leverage to lower layers using either
IPsec or TLS, if they can successfully satisfy the security
requirement of IPFIX data protection.
To protect the data on the wire, three levels of granularity SHOULD
be supported:
6.1.1. No security
No security is required when the transport between the IPFIX device
and the collector is perceived as safe. This option allows the
protocol to run most efficiently without extra overhead and an IPFIX
solution MUST support it.
6.1.2. Authentication only
The authentication only protection provides the IPFIX users the
assurance of data integrity and authenticity. The data exchanged
between the IPFIX device and the collector is protected by
authentication signature. Any modification of the IPFIX data will be
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detected by the recipient, resulting in discarding of the received
data. However, the authentication only option doesn't offer data
confidentiality. The IPFIX user SHOULD avoid use this option when
sensitive or confidential information is being exchanged. An IPFIX
solution SHOULD support this option. The authentication only option
SHOULD provide replay attack protection. Some means to achieve this
level of security are:
* TCP with MD5 options.
* IP Authentication Header
6.1.3. Encryption
Data encryption provides the best protection for IPFIX data. The
IPFIX data is encrypted at the sender and only the intended recipient
can decrypt and have access to the data. This option MUST be used
when the transport between the exporter and the collector are unsafe
and the IPFIX data needs to be protected. It is recommended to use
the underlying security layer functions for this purpose. Some means
to achieve this level of security are:
* Encapsulating Security Payload.
* Transport Layer Security Protocol
The data encryption option adds overhead to the IPFIX data transfer.
It may limit the rate that an export can report its flow to the
collector due to the heavy resource requirement of running
encryption.
6.2. IPFIX end point authentication
It is important to make sure that the IPFIX device is talking to the
"right" collector instead of a masqueraded collector. The same logic
also holds true from the collector point of view that it want to make
sure it is collecting the flow information from the "right" IPFIX
device. The IPFIX architecture SHOULD allow the authentication
capability so that either one-way or mutual authentication can be
performed between the IPFIX device and collector.
The IPFIX architecture SHOULD use the existing transport protection
protocols such as TLS to fulfill the authentication requirement.
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6.3. Denial of service (DoS) attack prevention
Since one of the potential usages for IPFIX is for intrusion
detection, it is important for the IPFIX architecture to support some
kind of DoS resistance.
6.3.1. Network under attack
The Network itself may be under attack, resulting in an overwhelming
number of IPFIX messages. The IPFIX SHOULD try to capture as much
information as possible. However, when large amount IPFIX messages
are generated in a short period of time, the IPFIX may become
overloaded.
6.3.2. Generic DoS attack on the IPFIX system
The IPFIX system may subject to generic DoS attacks, just as any
system on any open networks. These types of attacks are not IPFIX
specific. Preventing and responding to such types of attacks are out
of the scope of IPFIX WG.
6.3.3. IPFIX Specific DoS attack
There is a specific attack on the IPFIX portion of the IPFIX device
or Collector.
(To be added and discussed on the general list).
7. Flow Expiration
A flow is considered to be inactive if no packets of this flow has
been observed at the observation point for a given timeout interval.
The flow can be exported under the following conditions:
1. If the exporter can deduce the end of a flow, the exporter
SHOULD export the flow records when the end of the flow is
detected. For example: flow generated by TCP type of traffic
where the FIN or RST bits indicate the end of the flow
2. If the flow has been inactive for a certain period of time.
This inactivity timeout SHOULD be configurable. For example:
flow generated by UDP type of traffic.
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3. For long aging flows, the exporter SHOULD export the flow
records on regular basis, in order to:
a. Report the flow records periodic accounting information to
the collector
b. Avoid counter wrapping This activity timeout SHOULD be
configurable
4. If the exporter experiences resources constraints, a flow MAY be
prematurely expired (example: memory)
8. IANA Consideration
Need Port number assigned from IANA [more to be written]
9. References
[1] IP Flow Information Export (IPFIX)
<http://www.ietf.org/html.charters/ipfix-charter.html>
[2] J. Quittek ,T. Zseby, B. Claise,"Requirements for IP Flow
Information Export", (work in progress) ,Internet Draft, Internet
Engineering Task Force, <draft-ietf-ipfix-reqs-02.txt>, August 2002
[3] K.C. Norseth, Paul Calato,"Data Model for IP Flow Information
Export", (work in progress) ,Internet Draft, Internet Engineering
Task Force, <draft-ietf-ipfix-data-00.txt>, August 2002
10. Acknowledgements
We like to thank all the people contributing to the requirements
discussion on the mailing list, and the design teams for many
valuable comments.
George Carle
Tanja Zseby
Paul Calato
Dave Plonka
Kevin Zhang
KC Norseth
Benoit Claise
Ganesh Sadasivan
Vamsi Valluri
Cliff Wang
Ram Gopal
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Jc Martin
Carter Bullard
Juergen Quittek
Reinaldo Penno
Nevil Brownlee
Simon Leinen
11. Author's Addresses
Benoit Claise
Cisco Systems
De Kleetlaan 6a b1
1831 Diegem
Belgium
Phone: +32 2 704 5622
Email: bclaise@cisco.com
Ganesh Sadasivan
Cisco Systems, Inc.
170 W. Tasman Dr.
San Jose, CA 95134
USA
Phone: +1 (408) 527-0251
Email: gsadasiv@cisco.com
K.C. Norseth
Consultant
Phone: +1 (801) 546-3316
Email: kcn@norseth.com
Juergen Quittek
NEC Europe Ltd.
Adenauerplatz 6
69115 Heidelberg
Germany
Phone: +49 6221 90511-15
EMail: quittek@ccrle.nec.de
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12. Full Copyright Statement
"Copyright (C) The Internet Society (date). All Rights Reserved. This
document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into.
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