Internet DRAFT - draft-ietf-behave-syslog-nat-logging
draft-ietf-behave-syslog-nat-logging
Behave Working Group Z. Chen
Internet-Draft China Telecom
Intended status: Standards Track C. Zhou
Expires: July 29, 2014 T. Tsou
T. Taylor, Ed.
Huawei Technologies
January 25, 2014
Syslog Format for NAT Logging
draft-ietf-behave-syslog-nat-logging-06
Abstract
NAT devices are required to log events like creation and deletion of
translations and information about the resources the NAT is managing.
The logs are required to identify an attacker or a host that was used
to launch malicious attacks, and for various other purposes of
accounting and management. Since there is no standard way of logging
this information, different NAT devices behave differently. The lack
of a consistent way makes it difficult to write the collector
applications that would receive this data and process it to present
useful information.
This document describes the information that is required to be logged
by the NAT devices. It goes on to standardize formats for reporting
these events and parameters using SYSLOG (RFC 5424). A companion
document specifies formats for reporting the same events and
parameters using IPFIX (RFC 7011). Applicability statements are
provided in this document and its companion to guide operators and
implementors in their choice of which technology to use for logging.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 29, 2014.
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Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
2. Deployment Considerations . . . . . . . . . . . . . . . . . . 6
2.1. Static and Dynamic NATs . . . . . . . . . . . . . . . . . 6
2.2. Realms and Address Pools . . . . . . . . . . . . . . . . 7
2.2.1. Address Pools . . . . . . . . . . . . . . . . . . . . 7
2.3. NAT Logging Requirements For Different Transition Methods 8
2.4. Subscriber Identification . . . . . . . . . . . . . . . . 9
2.5. The Port Control Protocol (PCP) . . . . . . . . . . . . . 10
2.6. Logging At the Customer Edge . . . . . . . . . . . . . . 10
3. NAT-Related Events and Parameters . . . . . . . . . . . . . . 10
3.1. Events Relating To Allocation Of Resources To Hosts . . . 10
3.1.1. NAT Address Mapping Creation and Deletion . . . . . . 11
3.1.2. NAT Address and Port Mapping Creation and Deletion . 12
3.1.3. NAT Session Creation and Deletion . . . . . . . . . . 14
3.1.3.1. Destination Logging . . . . . . . . . . . . . . . 17
3.1.4. Port Range Allocation and Deallocation . . . . . . . 17
3.2. Threshold Events . . . . . . . . . . . . . . . . . . . . 19
3.2.1. Address Pool High- and Low-Water-Mark Threshold
Events . . . . . . . . . . . . . . . . . . . . . . . 19
3.2.2. Global Address Mapping High-Water-Mark Threshold
Event . . . . . . . . . . . . . . . . . . . . . . . . 20
3.2.3. Global Address and Port Mapping High-Water-Mark
Threshold Event . . . . . . . . . . . . . . . . . . . 21
3.2.4. Subscriber-Specific Address and Port Mapping
Threshold Event . . . . . . . . . . . . . . . . . . . 22
3.3. Limit-Related Events . . . . . . . . . . . . . . . . . . 22
3.3.1. Global Address Mapping Limit Exceeded . . . . . . . . 22
3.3.2. Global Address and Port Mapping Limit Exceeded . . . 23
3.3.3. Global Limit On Number of Active Hosts Exceeded . . . 24
3.3.4. Subscriber-Specific Limit On Number of Address and
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Port Mappings Exceeded . . . . . . . . . . . . . . . 25
3.3.5. Global Limit On Number Of Fragments Pending
Reassembly Exceeded . . . . . . . . . . . . . . . . . 26
4. SYSLOG Applicability . . . . . . . . . . . . . . . . . . . . 27
5. SYSLOG Record Format For NAT Logging . . . . . . . . . . . . 27
5.1. SYSLOG HEADER Fields . . . . . . . . . . . . . . . . . . 28
5.2. Parameter Encodings . . . . . . . . . . . . . . . . . . . 29
5.2.1. General Encoding Rules . . . . . . . . . . . . . . . 32
5.2.2. Special Cases . . . . . . . . . . . . . . . . . . . . 32
5.2.3. Relationship To Objects In the NAT MIB . . . . . . . 33
5.3. Encoding Of Complete Log Report For Each Event Type . . . 35
5.3.1. Encoding of Events Relating To Allocation Of
Resources To Hosts . . . . . . . . . . . . . . . . . 35
5.3.1.1. NAT Address Mapping Creation and Deletion . . . . 36
5.3.1.2. NAT Address and Port Mapping Creation and
Deletion . . . . . . . . . . . . . . . . . . . . 37
5.3.1.3. NAT Session Creation and Deletion . . . . . . . . 39
5.3.1.4. Port Range Allocation and Deallocation . . . . . 41
5.3.2. Encoding of Threshold Events . . . . . . . . . . . . 43
5.3.2.1. NAT Address Pool High- and Low-Water-Mark
Threshold Events . . . . . . . . . . . . . . . . 43
5.3.2.2. Global Address Mapping High-Water-Mark
Threshold Exceeded . . . . . . . . . . . . . . . 44
5.3.2.3. Global Address and Port Mapping High-Water-Mark
Threshold Event . . . . . . . . . . . . . . . . . 45
5.3.2.4. Subscriber-Specific Address and Port Mapping
High-Water-Mark Threshold Event . . . . . . . . . 45
5.3.3. Encoding of Limit Events . . . . . . . . . . . . . . 46
5.3.3.1. Global Address Mapping Limit Exceeded . . . . . . 46
5.3.3.2. Global Address and Port Mapping Limit Exceeded . 47
5.3.3.3. Global Limit On Number of Active Hosts Exceeded . 48
5.3.3.4. Subscriber-Specific Limit On Number of Address
and Port Mappings Exceeded . . . . . . . . . . . 49
5.3.3.5. Pending Fragment Limit Exceeded . . . . . . . . . 50
6. Management Considerations . . . . . . . . . . . . . . . . . . 51
6.1. General Requirements For Control Of Logging . . . . . . . 51
6.1.1. Configuration of PRI Value . . . . . . . . . . . . . 51
6.1.2. Ability For Each Collector To Detect Lost Event
Reports . . . . . . . . . . . . . . . . . . . . . . . 52
6.1.3. Ability To Rate Limit Or Disable Event Reports . . . 52
6.2. Setting Limits and Thresholds . . . . . . . . . . . . . . 53
6.3. Other Management Requirements . . . . . . . . . . . . . . 54
7. Security Considerations . . . . . . . . . . . . . . . . . . . 55
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 55
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 58
9.1. Normative References . . . . . . . . . . . . . . . . . . 58
9.2. Informative References . . . . . . . . . . . . . . . . . 60
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 61
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1. Introduction
This document deals with logging of NAT activity in two categories:
NAT translations and NAT resource usage.
Operators already need to record the addresses assigned to
subscribers at any point in time, for operational and regulatory
reasons. When operators introduce NAT devices that support address
sharing (e.g., Carrier Grade NATs (CGNs)) into their network,
additional information has to be logged. This document and
[I-D.behave-ipfix-nat-logging] are provided in order to standardize
the events and parameters to be recorded, using SYSLOG [RFC5424] and
IPFIX [RFC7011] respectively. The same content is proposed to be
logged by both documents.
In addition to records of subscriber activity, some operators use
logs to indicate when utilization of critical resources is
approaching or has reached limits set by the operator or
implementation. This document and the IPFIX document therefore
provide logs in two categories: thresholds exceeded and limits
exceeded. Operators have the alternative to receive the threshold
limits as SNMP notifications (see the NAT MIB [I-D.behave-NAT-MIB]).
Detailed logging requirements will vary depending on the context in
which they are used. For example, different methods for transition
from IPv4 to IPv6 require different events and different parameters
to be logged. Section 2 covers this topic.
Section 3 provides a detailed description of the events that need
logging and the parameters that may be required in the logs.
Section 3.1 describes events related to subscriber activity,
Section 3.2 covers threshold events, and Section 3.3 covers events
where hard limits have been reached.
The use of SYSLOG [RFC5424] has advantages and disadvantages compared
with the use of IPFIX [RFC7011]. Section 4 provides a statement of
applicability for the SYSLOG approach.
Section 5 specifies SYSLOG record formats for logging of the events
and parameters described in Section 3. Section 5.1 describes the
SYSLOG header format for each report, Section 5.2 lists and describes
the encoding of parameters that can appear in the logs, and
Section 5.3 specifies the encoding of the body of each event report.
The definitions provide the flexibility to vary actual log contents
based on the requirements of the particular deployment.
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1.1. Terminology
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 "Key words for use in
RFCs to Indicate Requirement Levels" [RFC2119].
This document makes frequent reference to the NAT MIB. That
reference is to the document [I-D.behave-NAT-MIB].
This document makes frequent reference to NAT behaviours defined in
[RFC4784]. In particular it refers to
o the recommended pooling behaviour "pooled" and its contrary
pooling behaviour "arbitrary"; and
o the recommended mapping behaviour "endpoint-independent" and its
contrary mapping behaviour "endpoint-dependent".
This document uses the term "address mapping" to denote an
association between an internal IP address and an IP address in a
selected external realm. See Section 2.2 for a further discussion of
this process.
The natMapIntAddrTable in the NAT MIB provides details on all
currently active address mappings. Note that this table is
applicable only when NAT pooling behaviour is "paired".
This document uses the [RFC4787] term "address and port mapping" to
denote a three-tuple association between an internal IP address and
port and an IP address and port in a selected external realm, or
between an internal <IP address, ICMP identifier> pair and an <IP
address, ICMP identifier> pair in the selected realm. For
implementations which maintain a Binding Information Base (BIB) (as
described in Section 2 of [RFC6146], for example), the content of a
BIB entry is an address and port mapping.
The natMappingTable in the NAT MIB provides details on all
currently active address and port mappings.
This document uses the term "session" as it is defined in [RFC2663],
Section 2.3. From the point of view of this document, session
creation involves the combination of a source address and port
mapping with a mapping between internal and external destination
address and port to create a full five-tuple mapping.
Except where a clear distinction is necessary, this document uses the
abbreviation "NAT" to encompass both Network Address Translation (NAT
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in the strict sense) and Network Address and Port Translation (NAPT).
The event report descriptions provided in this document apply to
NAPT, and can be simplified for pure NAT operation.
To match the terminology used by the NAT MIB, this document uses the
term "subscriber" to denote any device being served by the NAT,
whether individual host or customer edge router. That is, despite
the carrier-oriented terminology, the intended scope of applicability
of this document is both to NATs in the carrier network and managed
NATs in the customer network.
Finally, with two exceptions, when the terms "source" or
"destination" are used below, they denote the source and destination
of packets that are flowing from the internal to the external realm,
regardless of the direction of session establishment or the direction
of flow of an individual packet. The exceptions relate to the global
address and port mapping limit event and the pending fragment limit
event, when the actual source and destination addresses in the header
of the packet that hit the limit are reported.
2. Deployment Considerations
2.1. Static and Dynamic NATs
A NAT controls a set of resources in the form of one or more pools of
external addresses. If the NAT also does port translation (i.e., it
is a NAPT), it also controls the sets of UDP and TCP port numbers and
ICMP identifiers associated with each external address.
Logging requirements for a NAT depend heavily on its resource
allocation strategy. NATs can be classed as static or dynamic
depending on whether the resources provided to individual users are
pre-configured or allocated in real time as the NAT recognizes new
flows.
Static assignments can be logged at configuration time by the NAT or
by network infrastructure. The logging volume associated with static
assignments will be relatively low, of the order of the volume of
user logons.
Dynamic assignments typically require both more detail in the logs
and a higher volume of logs in total. A traditional Network Address
Port Translator (NAPT) as described in [RFC3022] and following the
recommendations of [RFC4787] and [RFC5382] will generate a new
address and port mapping each time it encounters a new internal
<address, port> combination.
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For statistical reasons, static assignments support lower address
sharing ratios than fully dynamic assignments as exemplified by the
traditional NAPT. The sharing ratio can be increased while
restraining log volumes by assigning ports to users in multi-port
increments as required rather than assigning just one port at a time.
A subscriber may start with no initial allocation, or may start with
an initial permanent allocation to which temporary increments are
added when the initial set is all being used. See [RFC6264] and
[I-D.tsou-behave-natx4-log-reduction] for details. If this strategy
is followed, logging will be required only when an increment is
allocated or reclaimed rather than every time an internal <address,
port> combination is mapped to an external <address, port>.
2.2. Realms and Address Pools
A realm identifies an IP numbering space. A NAT session always maps
between an internal and an external realm. In simple NAT
configurations, it may be possible to identify a default internal
realm and/or a default external realm for all sessions. In more
complex NAT configurations a given realm may be an internal realm for
some sessions and an external realm for others. Realms without
subscriber sites are always external.
Address pools are associated with specific realms in their external
role.
It is necessary to define multiple realms when the NAT supports
overlapping IP numbering spaces. In such a case, the NAT must
determine the source realm and subscriber using additional
information associated with the incoming packet. See further
discussion in Section 2.4.
2.2.1. Address Pools
An address pool is a mechanism for configuring the set of addresses
to which a given internal address can be mapped in a given realm.
The pool may be used simply to ration the available addresses within
that realm, or may be selected for other reasons such as to add
additional semantics (e.g., type of service required) to the external
address within the target realm. Clearly a given internal address
may be mapped into more than one address pool at a given time.
The model of an address pool assumed in this document and in the NAT
MIB is that the pool offers a fixed range of port/ICMP identifier
values, the same over all addresses within the pool. How these are
allocated to individual mappings depends on the pooling behaviour.
With a pooling behaviour of "arbitrary", the NAT can select any
address in the pool with a free port value for the required protocol
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and map the internal address to it. With the recommended pooling
behaviour of "paired", the NAT restricts itself to finding a free
port at the address to which the internal address is already mapped,
if there is one.
From this description, one can see that ports are a limited resource,
subject to exhaustion at the pool level and, with "paired" behaviour,
at the level of the individual address. Log events are defined in
Section 3.2.1 that allow monitoring of port utilization at the pool
level. Section 6.2 discusses how the thresholds for triggering these
events should be varied depending on pooling behaviour.
2.3. NAT Logging Requirements For Different Transition Methods
A number of transition technologies have been or are being developed
to aid in the transition from IPv4 to IPv6. 6rd [RFC5969] and DS-Lite
[RFC6333] are at the deployment stage. Several 'stateless'
technologies: Public IPv4 over IPv6 [RFC7040], MAP-E
[I-D.softwire-map], and Lightweight 4over6 [I-D.softwire-lw4over6]
have seen experimental deployment and are in the process of being
standardized at the time of writing of this document.
Of the technologies just listed, 6rd and Public IPv4 over IPv6 do not
involve NATs and hence need not be considered further. The other
techniques involve NAT at the customer edge, at the border router, or
both, and hence are in scope.
A DS-Lite Address Family Transition Router (AFTR) includes a large-
scale session-stateful NAT44 processing potentially millions of
sessions per second. The special character of AFTR operation over
that of a traditional NAT44 is that the source IPv4 addresses of the
internal hosts will not be unique. As a consequence, identification
of the realm and subscriber from which the packet was sent needs to
include an additional identifier associated with the subscriber host.
For basic DS-Lite, this will be the IPv6 address used to encapsulate
the packets outgoing from the host. See Section 6.6 of [RFC6333].
For gateway-initiated DS-Lite [RFC6674], two identifiers are needed:
an identifier of the softwire from the gateway to the NAT, and an
identifier associated with the incoming tunnel to the gateway.
The DS-Lite customer edge equipment (the 'B4') may also perform NAT44
functions, similar to the functions performed by traditional NAT44
devices.
As a NAT44, the DS-Lite AFTR may be fully dynamic, or may allocate
ports in increments as described in the previous section.
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Lightweight 4over6 [I-D.softwire-lw4over6] and MAP-E
[I-D.softwire-map] both require NAT44 operation at the customer edge.
In both cases the resource allocation strategy is static. Thus any
logging of resource allocation for these two transition techniques
can be done by the network at configuration time.
2.4. Subscriber Identification
The ability to identify the particular subscriber involved in an
event is required for the events defined in Section 3.1, and
desirable for technician follow-up for those defined in Section 3.2.4
and Section 3.3.
As mentioned above, in some NAT configurations the source address is
insufficient to identify an individual subscriber because of
overlapping address space, and additional information is required.
For example, if the NAT supports DS-Lite [RFC 6333], the source
address of incoming packets from DS-Lite subscribers will always be
in the range 192.0.0/29. The additional information required in this
case is the IPv6 address of the encapsulating header.
The natSubscribersTable in the NAT MIB contains the additional
information needed, if any, to identify each subscriber. Thus it is
sufficient to include the index to this table in the event report to
provide the needed identification. However, this implies that for
full interpretation of the event report, the configuration
information stored in the natSubscribersTable must be stored (along
with AAA information relating the additional identifiers to the
subscriber profiles, which must be stored in any event). To relieve
the operator of the need to store the configuration data (given that
the logs may be needed months or years after they were recorded), the
reports specified in Section 3.1 include the additional identifying
information that is found in the natSubscribersTable.
This document standardizes the presentation of the following possible
additional classifying information within NAT-related log reports:
o interface index [RFC2863];
o VLAN index [RFC4363];
o VPN identifier [RFC4265];
o DS-Lite encapsulating IPv6 address [RFC6333].
Which of these is actually used in a given NAT depends on
implementation and deployment.
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Gateway-Initiated DS-Lite [RFC6674] identifiers could also be
specified, but it seems premature to do so because it is not clear
which of the variety of possibilities presented in Section 6 and
Appendix A.2 of [RFC6674] are actually being deployed.
2.5. The Port Control Protocol (PCP)
The Port Control Protocol (PCP) [RFC6887] and its port set extension
[I-D.pcp-port-set] can be viewed as a way to provision ports by other
means. However, PCP can be invoked on a per-flow basis, so the
volume of logs generated by a PCP server can be closer to the volume
associated with a fully dynamic NAT. The volume really depends on
how PCP is being used in a specific network.
2.6. Logging At the Customer Edge
Logging at the customer edge (or at the ISP edge for NATs protecting
the ISP's internal networks) may be done by the customer for purposes
of internal management, or by the ISP for its own administrative and
regulatory purposes. Given the likelihood of a high internal
community of interest, it is possible but unlikely that a NAT at the
edge of a large enterprise network processes a number of new packet
flows per second which is comparable to the volume handled by a
carrier grade NAT. Most customer edge NATs will handle a much
smaller volume of flows.
3. NAT-Related Events and Parameters
The events which follow were initially gleaned, in the words of the
authors of [I-D.behave-ipfix-nat-logging], from [RFC4787] and
[RFC5382]. Some details were subsequently informed by the discussion
in Section 2 and by provisions within the NAT MIB. Section 4 of
[RFC6888] also provides a brief statement of logging requirements for
carrier grade NATs.
In SYSLOG, the timestamp and the event type will appear in the log
header rather than as an explicit part of the structured data portion
of the log. Hence they are omitted from the parameter tabulations
that follow.
Parameters marked CONDITIONAL are REQUIRED under some circumstances
but not others. Details are provided for each event.
3.1. Events Relating To Allocation Of Resources To Hosts
Setting up a NAT session proceeds in a series of logical steps:
creation of an address mapping, creation of an address and port
mapping, and finally, creation of the session.
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The reports corresponding to these three steps are defined in
Section 3.1.1, Section 3.1.2, and Section 3.1.3 respectively. Which
of these reports is enabled depends on the NAT implementation and
operator preferences, subject to the considerations of the next
paragraph.
If the NAT implements the recommended pooling behaviour of "paired",
address mapping creation is an event distinct in general from the
creation of a subsequent address and port mapping based on that
address mapping. However, if the pooling behaviour is "arbitrary"
[RFC4787], the two events occur simultaneously and there is no point
in reporting both. Similarly, if the NAT implements the recommended
mapping behaviour of "endpoint-independent mapping", the two events
of address and port mapping creation and session creation based on
that mapping are distinct and may meaningfully be reported
separately. However, if the mapping behaviour is "endpoint-
dependent", the two events occur simultaneously and it is only
meaningful to report session creation.
The fourth report type in this section describes the bulk allocation
of ports to an address mapping, which the NAT may implement if the
pooling behaviour is "paired" [RFC4787]. It, along with the other
reports, is needed to provide complete accountability for resources
allocated to the subscriber.
3.1.1. NAT Address Mapping Creation and Deletion
Two specific events are provided:
o NAT address mapping creation;
o NAT address mapping deletion.
Implementations MUST NOT report these events unless pooling behaviour
is "paired".
Address mapping is discussed in detail in Section 2.2.
One address mapping creation event is associated with potentially
many succeeding address and port mapping creation events, as
individual port values are mapped for specific protocols. Similarly,
an address mapping deletion event may be associated with potentially
many address and port mapping deletion events, which may have
preceded it over a period of time or may occur at the same time as a
result of the address unbinding.
The address mapping events take the following specific parameters:
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o NAT instance identifier (CONDITIONAL);
o Source subscriber index (MANDATORY);
o Additional source subscriber classifier value as recognized at the
ingress to the internal realm (CONDITIONAL);
o Internal realm (CONDITIONAL);
o Internal address type (MANDATORY);
o Internal source IP address (MANDATORY);
o External realm (CONDITIONAL);
o External address type (MANDATORY);
o External source IP address (MANDATORY);
o Trigger for address mapping creation or deletion (OPTIONAL):
* outgoing packet;
* administrative action (e.g., via the Port Control Protocol
[RFC6887]); or
* autonomous action of the NAT.
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
o Additional source subscriber classifier value REQUIRED if the
internal source IP address is not enough to identify the
subscriber unambiguously, else MUST NOT appear.
o Internal or external realm REQUIRED if not the default internal or
external realm, respectively, else MAY appear.
3.1.2. NAT Address and Port Mapping Creation and Deletion
The address and port mapping creation or deletion event reports the
addition or deletion of an address and port mapping as defined in
Section 1.1. If the implementation maintains a Binding Information
Base (BIB), this is equivalent to the creation or deletion of a BIB
entry. Implementations MUST support the generation of the address
and port mapping creation/deletion event reports if they implement
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the recommended mapping behaviour "endpoint-independent". They MAY
support reporting of these events in the contrary case.
The address and port mapping creation/deletion event report provides
the same information as the session creation/deletion event, except
for the destination-related fields and (in general) timestamp values
in the latter. With "endpoint-independent" mapping behaviour, one
address and port mapping creation event is associated with
potentially many succeeding session creation events. Similarly, an
address and port mapping deletion event will be associated with
potentially many session deletion events, which may have preceded it
over a period of time or may occur at the same time as a result of
the address and port mapping deletion.
Operators should disable the reporting of address and port mapping
creation and deletion events when destination logging is enabled,
because of the redundancy between the address and port mapping and
session event reports. However, if destination logging is disabled
and the NAT uses the recommended "endpoint-independent" mapping
behaviour, it is the session events that are redundant and should be
disabled.
The following specific events are defined:
o NAT address and port mapping creation
o NAT address and port mapping deletion
These take the same parameters for all types of NAT. The internal
realm, subscriber-identifying information, internal source IP
address, external realm, and external source IP address capture the
underlying address mapping. The port values and protocol are unique
to the address and port mapping.
The parameters for the address and port mapping creation/deletion
event are:
o NAT instance identifier (CONDITIONAL);
o Source subscriber index (MANDATORY);
o Additional source subscriber classifier value as recognized at the
ingress to the internal realm (CONDITIONAL);
o Internal realm (CONDITIONAL);
o Internal address type (MANDATORY);
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o Internal source IP address (MANDATORY);
o Internal source port or ICMP identifier (MANDATORY);
o External realm (CONDITIONAL);
o External address type (MANDATORY);
o External source IP address (MANDATORY);
o External source port or ICMP identifier (MANDATORY);
o Protocol identifier (MANDATORY);
o Trigger for address and port mapping creation or deletion
(OPTIONAL):
* outgoing packet received;
* incoming packet received;
* administrative action (e.g., via the Port Control Protocol
[RFC6887]); or
* deletion of the underlying address mapping (applicable only if
pooling behaviour is "paired" [RFC4787]).
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
o Additional source subscriber classifier value REQUIRED if the
internal source IP address is not enough to identify the
subscriber unambiguously, else MUST NOT appear.
o Internal or external realm REQUIRED if not the default internal or
external realm, respectively, else MAY appear.
3.1.3. NAT Session Creation and Deletion
A NAT session creation or deletion event is logged when a address and
port mapping is further bound to or unbound from a specific
destination address and port in the external realm. One to many
sessions can be based on the same address and port mapping.
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Implementations MUST provide a means for the operator to specify
whether destination information is to be included in the reports of
these events (see discussion below).
The following specific events are defined:
o NAT session creation
o NAT session deletion
These take the same parameters for all types of NAT. Parameters
"internal realm" through "protocol identifier" capture the underlying
address and port mapping. Subsequent parameters capture the
destination address and destination subscriber identity (if
applicable).
The parameters for the session creation/deletion event are:
o NAT instance identifier (CONDITIONAL);
o Internal source subscriber index, equal to the natSubscriberIndex
value in the natSubscribersTable in the NAT MIB (MANDATORY);
o Additional internal subscriber classifier value (CONDITIONAL);
o Internal realm (CONDITIONAL);
o Internal address type (MANDATORY);
o Internal source IP address (MANDATORY);
o Internal source port or ICMP identifier (MANDATORY);
o External realm (CONDITIONAL);
o External address type (MANDATORY);
o External source IP address (MANDATORY);
o External source port or ICMP identifier (MANDATORY);
o Protocol identifier (MANDATORY);
o Internal destination IP address (CONDITIONAL);
o Internal destination port or ICMP identifier (CONDITIONAL);
o Destination subscriber index (CONDITIONAL);
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o Additional destination subscriber classifier value as recognized
at the ingress to the external realm (CONDITIONAL);
o External destination IP address (CONDITIONAL);
o External destination port or ICMP identifier (CONDITIONAL);
o Trigger for session creation or deletion (OPTIONAL):
* outgoing packet received;
* incoming packet received;
* administrative action (e.g., via the Port Control Protocol
[RFC6887]); or
* deletion of the underlying address and port mapping (applicable
only if the NAT mapping behaviour is "endpoint-independent".
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
o Additional source subscriber classifier value REQUIRED if the
internal source IP address is not enough to identify the
subscriber unambiguously, else MUST NOT appear.
o Internal or external realm REQUIRED if not the default internal or
external realm, respectively, else MAY appear.
o Internal destination address and port REQUIRED if destination
logging is enabled and these need to be remapped to external
destination address and port. Otherwise, if destination logging
is disabled, they MUST NOT appear, and if destination logging is
enabled, they SHOULD NOT appear because of redundancy.
o External destination subscriber index REQUIRED if destination
logging is enabled and the destination is a subscriber served by
the NAT, else MUST NOT appear.
o Additional external subscriber classifier value REQUIRED if
destination logging is enabled and the destination is a subscriber
served by the NAT and the external destination address is not
enough to identify the external destination subscriber
unambiguously, else MUST NOT appear.
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o External destination address and port REQUIRED if destination
logging is enabled, else MUST NOT appear.
3.1.3.1. Destination Logging
The logging of destination address and port is undesirable, for
several reasons. [RFC6888] recommends against destination logging
because of the privacy issues it creates. From an operator's point
of view, destination logging is costly not just because of the volume
of logs it will generate, but because the NAT now has to carry
additional session state so that it only needs to log once per
session between two transport end points rather than logging every
packet. Finally, [RFC4787], etc. recommend the use of endpoint-
independent mapping to maximize the ability of applications to
operate through the NAT. In that case, most of the contents of the
session creation event report will be repeated for one destination
after another.
One possibility is that the implementation provides the operator with
the ability to log destinations only for particular subscribers or
particular mapped addresses on a special study basis. This facility
could be used for trouble-shooting or malicious activity tracing in
particular cases as required. If such a capability is provided, the
implementation MUST report destination information for sessions
matching the specified criteria, but MUST NOT report these events for
other sessions.
3.1.4. Port Range Allocation and Deallocation
This event is recorded at a hybrid NAT whenever the set of ports
allocated to a given address mapping changes. It is assumed that
when ports are allocated in bulk, the same values are allocated for
all protocols.
The following specific events are defined:
o Port range allocation;
o Port range deallocation.
The parameters for these events are:
o NAT instance identifier (CONDITIONAL);
o Source subscriber index (MANDATORY);
o Additional source subscriber classifier value as recognized at the
ingress to the internal realm (CONDITIONAL);
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o Internal realm (CONDITIONAL);
o Internal address type (MANDATORY);
o Internal source IP address (MANDATORY);
o External realm (CONDITIONAL);
o External address type (MANDATORY);
o External source IP address (MANDATORY);
o Lowest port number of the range being allocated or deallocated
(MANDATORY).
o Highest port number of the range being allocated or deallocated
(MANDATORY).
o Trigger for port range allocation or deallocation (OPTIONAL):
* outgoing packet received;
* incoming packet received;
* administrative action (e.g., via the Port Control Protocol
[RFC6887]); or
* autonomous action of the NAT.
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
o Additional source subscriber classifier value REQUIRED if the
internal source IP address is not enough to identify the
subscriber unambiguously, else MUST NOT appear.
o Internal or external realm REQUIRED if not the default internal or
external realm, respectively, else MAY appear.
It will be necessary to use multiple event reports to report more
complex allocations or deallocations.
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3.2. Threshold Events
The events of this section are based on thresholds set by the
operator within the NAT MIB. Cross-references to the associated MIB
objects are provided for each event. With the exception of the
address pool low-water-mark event, the threshold events provide early
warning of potential dropped packets due to resource exhaustion or
administrator-imposed limits.
3.2.1. Address Pool High- and Low-Water-Mark Threshold Events
Two specific events provide reports on address pool utilization:
o High-water-mark threshold reached or exceeded;
o Low-water-mark threshold reached or under-shot.
Depending on deployment the operator has the alternative of using the
SNMP notifications natNotifPoolWater-MarkHigh and natNotifPoolWater-
MarkLow defined in the NAT MIB rather than logging these events.
Address pools are discussed in Section 2.2.1. The
natPoolTable object in the NAT MIB provides access to parameters
describing the utilization level of address-port combinations within
a given pool. Since a new mapping cannot be allocated unless a
mappable address and a free port on that address are available, it is
important to know when the available set of address-port combinations
within a given pool is nearing exhaustion. Hence the
natPoolTable contains a high-water-mark threshold settable by the
operator. An address pool high-water-mark event report is generated
when a new mapping into the pool is requested and aggregate address-
port utilization is equal to or greater the threshold.
Similarly it can be of interest to know when a pool is under-
utilized. Hence the natPoolTable also provides a low-water-mark
threshold. An address pool low-water-mark event report is generated
when aggregate address-port utilization is equal to or less than the
low-water-mark threshold.
Section 6.2 discusses factors affecting the choice of the threshold
values.
The high-water-mark threshold event provides a warning that the
address-port combinations offered by the pool are nearing exhaustion.
Upon exhaustion, subscribers may be unable to establish new
connections because no address has enough free port values left to be
allocated to an address mapping ("address exhaustion"). This applies
to the case of "paired" pooling behaviour, where typically an address
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will not be allocated unless it has a sufficient number of free
ports. Alternatively, new connections cannot be established simply
because no address in the pool has a free port number for the
required protocol ("port exhaustion").
Packets triggering failed attempts to establish new connections due
to address exhaustion are included in the following NAT MIB dropped
packet counters:
o globally, natResourceErrors in the natCounters table;
o per protocol, natProtocolResourceErrors in natProtocolTable;
o per subscriber, natSubscriberResourceErrors in
natSubscribersTable.
Packets triggering failed attempts to establish new connections due
to port exhaustion are counted in the following NAT MIB dropped
packet counters:
o globally, natOutOfPortErrors in the natCounters table;
o per protocol, natProtocolOutOfPortErrors in natProtocolTable;
o per subscriber, natSubscriberOutOfPortErrors in
natSubscribersTable.
An address pool threshold event report contains the following
specific parameters:
o NAT instance identifier (CONDITIONAL);
o Pool identifier (MANDATORY);
o The threshold value set by the administrator (MANDATORY).
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
3.2.2. Global Address Mapping High-Water-Mark Threshold Event
One specific event allows monitoring of the total number of mappings
between internal and external addresses:
o Address mapping high-water-mark threshold exceeded.
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Implementations MUST NOT generate this event report unless the
pooling behaviour is "paired". Depending on deployment, operators
can choose instead to use the SNMP notification natNotifAddrMappings
defined in the NAT MIB.
The NAT MIB displays cumulative counts of address mappings created
and removed in the natCounters table. When the difference between
these two counters is greater than the threshold
natAddrMapNotifyThreshold provided in the natLimits table the global
address binding high-water-mark threshold event is reported.
The specific parameters provided by this event report are:
o NAT instance identifier (CONDITIONAL);
o Current number of active address mappings (MANDATORY).
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
3.2.3. Global Address and Port Mapping High-Water-Mark Threshold Event
One specific event allows monitoring of the total number of active
address and port mappings. Where the NAT implements a BIB, this is
equivalent to the total number of BIB entries.
o address and port mapping high-water-mark threshold exceeded.
Depending on deployment, operators can choose instead to use the SNMP
notification natNotifMappings defined in the NAT MIB.
The NAT MIB displays cumulative counts of address and port mappings
created and removed in the natCounters table. When the difference
between these two counters is greater than the threshold
natMappingsNotifyThreshold provided in the natLimits table the global
mapping high-water-mark threshold event is reported.
The specific parameters provided by this event report are:
o NAT instance identifier (CONDITIONAL);
o Current number of active address and port mappings (MANDATORY).
Conditions:
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o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
3.2.4. Subscriber-Specific Address and Port Mapping Threshold Event
An event is provided to allow monitoring of the total number of
active mappings per subscriber:
o Subscriber-specific mapping high-water-mark threshold exceeded.
Depending on deployment, operators can choose instead to use the SNMP
notification natNotifSubscriberMappings defined in the NAT MIB.
The NAT MIB displays cumulative counts of address and port mappings
created and removed per subscriber in the natSubscribersTable. When
the difference between these two counters is greater than the
threshold natSubscriberMapNotifyThresh provided in that table the
subscriber address and port mapping high-water-mark threshold event
is reported.
The specific parameters provided by this event report are:
o NAT instance identifier (CONDITIONAL);
o Index of the affected subscriber (MANDATORY).
o Current number of active mappings for this subscriber (MANDATORY).
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
3.3. Limit-Related Events
The events of this section are generated when hard limits set by the
operator are exceeded. The consequence for service will be dropped
packets. As with the threshold events, the description of each
report includes cross-references to the associated MIB objects.
3.3.1. Global Address Mapping Limit Exceeded
The global address mapping limit exceeded event is reported when a
new address mapping is requested but the total number of address
mappings would exceed an administrative limit if it were added. The
limit is given by object natLimitAddressMappings in the natLimits
table of the NAT MIB. MIB counters giving number of packets dropped
due to resource limitations including this one are:
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o globally, natResourceErrors in the natCounters table;
o per protocol, natProtocolResourceErrors in natProtocolTable;
o per subscriber, natSubscriberResourceErrors in
natSubscribersTable.
Implementations MUST NOT generate this event report unless the
pooling behaviour is "paired". Depending on deployment, operators
can choose instead to use the SNMP notification natNotifAddrMappings
defined in the NAT MIB.
The parameters for this event are:
o NAT instance identifier (CONDITIONAL);
o Index of the affected subscriber (MANDATORY).
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
The subscriber index is provided to allow the operator to correlate
the event with any subscriber complaints or possible abuse.
3.3.2. Global Address and Port Mapping Limit Exceeded
The global address and port mapping limit exceeded event is reported
when a new address and port mapping is requested but the total number
of address and port mappings would exceed an administrative limit if
it were added. The limit is given by object natLimitMappings in the
natLimits table of the NAT MIB. MIB counters giving number of
packets dropped due to resource limitations including this one are:
o globally, natResourceErrors in the natCounters table;
o per protocol, natProtocolResourceErrors in natProtocolTable;
o per subscriber, natSubscriberResourceErrors in
natSubscribersTable.
The parameters for this event are:
o NAT instance identifier (CONDITIONAL);
o Index of the internal subscriber (CONDITIONAL);
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o Index of the external subscriber (CONDITIONAL);
o Source realm of the triggering packet (MANDATORY);
o Incoming packet header IP address type (CONDITIONAL);
o Incoming packet source IP address (CONDITIONAL).
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
o The index of the internal subscriber is REQUIRED if the mapping
was triggered by a packet outgoing from the internal to the
external realm, else MUST NOT appear.
o The index of the external subscriber is REQUIRED if the mapping
was triggered by a packet incoming from a subscriber served by the
NAT and located in the external realm (i.e., using an address
mapping created previously by the internal subscriber), else MUST
NOT appear.
o The address type and source IP address from the initiating packet
are REQUIRED if the mapping was triggered by a packet incoming
from a purely external realm (i.e., using an address mapping
created previously by the internal subscriber), else MAY appear.
The subscriber index or packet source address is provided to allow
the operator to correlate the event with any subscriber complaints or
possible abuse.
3.3.3. Global Limit On Number of Active Hosts Exceeded
The global limit on number of active hosts exceeded event is reported
when an address mapping is requested (at least at the logical level)
for a host with no previous active mappings, but the total number of
active hosts would exceed an administrative limit if it were added.
The limit is given by object natLimitSubscribers in the natLimits
table of the NAT MIB. MIB counters giving number of packets dropped
due to resource limitations including this one are:
o globally, natResourceErrors in the natCounters table;
o per protocol, natProtocolResourceErrors in natProtocolTable;
o per subscriber, natSubscriberResourceErrors in
natSubscribersTable.
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The parameters for this event are:
o NAT instance identifier (CONDITIONAL);
o Index of the affected subscriber (MANDATORY).
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
The subscriber index is provided to allow the operator to correlate
the event with any subscriber complaints.
3.3.4. Subscriber-Specific Limit On Number of Address and Port Mappings
Exceeded
The subscriber-specific limit on number of address and port mappings
exceeded event is reported when a new mapping is requested, but the
total number of active mappings for that subscriber would exceed an
administrative limit if it were added. The limit is given by object
natSubscriberLimitMappings in natSubscribersTable in the NAT MIB.
MIB counters giving number of packets dropped due to resource
limitations including this one are:
o globally, natResourceErrors in the natCounters table;
o per protocol, natProtocolResourceErrors in natProtocolTable;
o per subscriber, natSubscriberResourceErrors in
natSubscribersTable.
The parameters for this event are:
o NAT instance identifier (CONDITIONAL);
o Index of the affected subscriber (MANDATORY).
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
The subscriber index is provided to allow the operator to take
administrative action or to correlate the event with any subscriber
complaints or possible abuse.
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3.3.5. Global Limit On Number Of Fragments Pending Reassembly Exceeded
The global limit on number of fragments pending reassembly exceeded
event is reported when a new fragment is received and the number of
fragments currently awaiting reassembly is already equal to an
administrative limit. That limit is given by the natLimitFragments
object in the natLimits table. This event MUST NOT be reported
unless the NAT supports the "receive fragments out of order" behavior
[RFC4787]. MIB counters giving number of packets dropped due to
resource limitations including this one are:
o globally, natResourceErrors in the natCounters table;
o per protocol, natProtocolResourceErrors in natProtocolTable;
o per subscriber, natSubscriberResourceErrors in
natSubscribersTable.
The parameters for this event provide the contents of the IP header
of the received fragment that triggered it. If the source of the
packet is a subscriber served by the NAT and the subscriber index can
be determined, it MUST also be included.
o NAT instance identifier (CONDITIONAL);
o Source realm of the packet (MANDATORY);
o Packet header IP address type (MANDATORY);
o Packet source IP address (MANDATORY);
o Packet destination IP address (MANDATORY);
o Source subscriber index (CONDITIONAL).
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
o Source subscriber index REQUIRED if the source of the packet is a
subscriber served by the NAT and can be determined, else MUST NOT
appear.
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4. SYSLOG Applicability
The primary advantage of SYSLOG is the human readability and
searchability of its contents. In addition, it has built-in priority
and other header fields that allow for separate routing of reports
requiring management action. Finally, it has a well-developed
underpinning of transport and security protocol infrastructure.
SYSLOG presents two obstacles to scalability: the fact that the
records will typically be larger than records based on a binary
protocol such as IPFIX, and, depending on the architectural context,
the reduced performance of a router that is forced to do text
manipulation in the data plane. One has to conclude that for larger
message volumes, IPFIX should be preferred as the reporting medium on
the NAT itself. It is possible that SYSLOG could be used as a back-
end format on an off-board device processing IPFIX records in real
time, but this would give a limited boost to scalability. One
concern expressed in list discussion is that when the SYSLOG
formatting process gets overloaded records will be lost.
As a result, the key question is what the practical cutoff point is
for the expected volume of SYSLOG records, on-board or off-board the
NAT. This obviously depends on the computing power of the formatting
platform, and also on the record lengths being generated.
Information has been provided to the BEHAVE list at the time of
writing to the effect that one production application is generating
an average of 150,000 call detail records per second, varying in
length from 500 to 1500 bytes. Capacities several times this level
have been reported involving shorter records, but this particular
application has chosen to limit the average in order to handle peaks.
As illustrated by the example in Section 5.3.1.3, if destination
logging is enabled, typical record sizes for session event logs are
in the order of 300 bytes, so throughput capacity should be higher
than in the call detail case for the same amount of computing power.
However, note that bursts of session deletion events may occur as a
result of deletion of the underlying mapping or address mapping.
In private communication, a discussant has noted a practical limit of
a few hundred thousand SYSLOG records per second on a router.
5. SYSLOG Record Format For NAT Logging
This section describes the SYSLOG record format for NAT logging in
terms of the field names used in [RFC5424] and specified in Section 6
of that document. In particular, this section specifies values for
the APP-NAME and MSGID fields in the record header, the SD-ID
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identifying the STRUCTURED-DATA section, and the PARAM-NAMEs and
PARAM-VALUE types for the individual possible parameters within that
section. The specification is in three parts, covering the header,
encoding of the individual parameters, and encoding of the complete
log record for each event type.
5.1. SYSLOG HEADER Fields
Within the HEADER portion of the SYSLOG record, the priority (PRI)
level is subject to local policy, but a Severity value of 6
(Informational) is suggested for the events relating to creation and
deletion of sessions, mappings, address mappings, and port
allocation, combined with a suitable Facility value in the range
16-23 (local use) to ensure routing to a secure collector. The
Facility value(s) for the threshold and limit events will presumably
be chosen to route them to maintenance for immediate action and/or to
provisioning for less urgent consideration. The suggested value of
Severity by event type is shown in Table 1, but in practice has a
clear dependency on the context within which the NAT is operating.
The TIMESTAMP field SHOULD be expressed with sufficient precision to
distinguish non-simultaneous event occurrences, subject to the
accuracy of the local clock. This specification does not assume the
ability to correlate the events reported by the subject device with
events recorded by other devices, although that may be required for
other reasons. Hence from the point of view of this specification
only relative rather than absolute accuracy is of interest.
The HOSTNAME header field MUST identify the NAT device. The value of
the HOSTNAME field is subject to the preferences given in
Section 6.2.4 of [RFC5424].
The values of the APP-NAME and MSGID fields in the record header
determine the semantics of the record. To simplify log collection
procedures, the APP-NAME value "NAT" MUST be used for the event
reports specified in Section 5.3.1, the APP-NAME value "NATTHR" MUST
be used for the event types defined in Section 5.3.2, and the APP-
NAME value "NATLIM" MUST be used for the event types defined in
Section 5.3.3.
The MSGID values indicate the individual events. They are listed in
Table 1 for each of the events defined in Section 3. The table also
shows the SD-ID value used to label the event-specific STRUCTURED-
DATA element.
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+-------------------------+----------+---------+----------+---------+
| Event | APP-NAME | MSGID | Severity | SD-ID |
+-------------------------+----------+---------+----------+---------+
| NAT address mapping | NAT | AMADD | 6 info | namap |
| creation | | | | |
| NAT address mapping | NAT | AMDEL | 6 info | namap |
| deletion | | | | |
| NAT address and port | NAT | APMADD | 6 info | napmap |
| mapping creation | | | | |
| NAT address and port | NAT | APMDEL | 6 info | napmap |
| mapping deletion | | | | |
| NAT session creation | NAT | SADD | 6 info | nsess |
| NAT session deletion | NAT | SDEL | 6 info | nsess |
| Port range allocation | NAT | PTADD | 6 info | nprng |
| Port range deallocation | NAT | PTDEL | 6 info | nprng |
| | | | | |
| Address pool high | NATTHR | POOLHT | 4 | npool |
| threshold | | | warning | |
| Address pool low | NATTHR | POOLLT | 6 info | npool |
| threshold | | | | |
| Global address mapping | NATTHR | GAMHT | 4 | ngamht |
| high threshold | | | warning | |
| Global address and port | NATTHR | GAPMHT | 4 | ngapmht |
| mapping high threshold | | | warning | |
| Subscriber-specific | NATTHR | SAPMHT | 5 notice | nsapmht |
| mapping high threshold | | | | |
| | | | | |
| Global address mapping | NATLIM | GAMLIM | 3 error | ngaml |
| limit | | | | |
| Global address and port | NATLIM | GAPMLIM | 3 error | ngapml |
| mapping limit | | | | |
| Global active | NATLIM | GSLIM | 3 error | ngsl |
| subscriber limit | | | | |
| Subscriber-specific | NATLIM | SAPMLIM | 5 notice | nsapml |
| address and port | | | | |
| mapping limit | | | | |
| Pending fragment limit | NATLIM | FRAG | 4 | nfpkt |
| | | | warning | |
+-------------------------+----------+---------+----------+---------+
Table 1: Recommended MSGID Encodings and Default Severity Values for
the Events Defined In Section 3
5.2. Parameter Encodings
This section describes how to encode the individual parameters that
can appear in NAT-related logs. The parameters are taken from the
event descriptions in Section 3. The PARAM-NAMEs, brief
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descriptions, and encoding are listed in Table 2, with reference to
the general and special case encoding rules which follow.
+------------+-----------------------------------------+------------+
| PARAM-NAME | Description | Encoding |
+------------+-----------------------------------------+------------+
| | Miscellaneous | |
| | | |
| NATINST | NAT instance identifier | Text |
| TRIG | Trigger for event | Special |
| | | case |
| | | |
| | Subscriber-identifying information | |
| | | |
| SSUBIX | Source subscriber index | 32-bit |
| | | field |
| SIFIX | Source subscriber ingress interface | Special |
| | index list | case |
| SVLAN | Source subscriber ingress VLAN index | 32-bit |
| | | field |
| SVPN | Source subscriber ingress VPN Id | Special |
| | | case |
| SV6ENC | Source subscriber ingress RFC6333 | IPv6 |
| | encapsulating IPv6 address | address |
| DSUBIX | Destination subscriber index | 32-bit |
| | | field |
| DIFIX | Destination subscriber ingress | Special |
| | interface index list | case |
| DVLAN | Destination subscriber ingress VLAN | 32-bit |
| | index | field |
| DVPN | Destination subscriber ingress VPN Id | Special |
| | | case |
| DV6ENC | Destination subscriber ingress RFC6333 | IPv6 |
| | encapsulating IPv6 address | address |
| | | |
| | Internal packet description | |
| | | |
| IRLM | Internal realm | Text |
| IATYP | Internal IP address type | "IPv4" or |
| | | "IPv6" |
| ISADDR | Internal source IP address value | IPv4 or |
| | | IPv6 |
| | | address |
| ISPORT | Internal source port or ICMP identifier | 16-bit |
| | value | field |
| IDADDR | Internal destination IP address value | IPv4 or |
| | | IPv6 |
| | | address |
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| IDPORT | Internal destination port or ICMP | 16-bit |
| | identifier value | field |
| PROTO | Protocol identifier (from the IANA | 8-bit |
| | Assigned Internet Protocol Numbers | field |
| | registry) | |
| | | |
| | External (mapped) packet description | |
| | | |
| XRLM | External realm | Text |
| XATYP | External IP address type | "IPv4" or |
| | | "IPv6" |
| XSADDR | External source IP address value | IPv4 or |
| | | IPv6 |
| | | address |
| XSPORT | External source port or ICMP identifier | 16-bit |
| | value | field |
| XDADDR | External destination IP address value | IPv4 or |
| | | IPv6 |
| | | address |
| XDPORT | External destination port or ICMP | 16-bit |
| | identifier value | field |
| | | |
| | Port range description | |
| | | |
| PORTMN | Port range lowest value | 16-bit |
| | | field |
| PORTMX | Port range highest value | 16-bit |
| | | field |
| | | |
| | Values related to thresholds | |
| | | |
| POOLID | Address pool identifier | 32-bit |
| | | field |
| POOLHW | Address pool high water mark threshold | Unsigned |
| | | decimal |
| POOLID | Address pool low water mark threshold | Unsigned |
| | | decimal |
| GAMCNT | Current global number of address | Unsigned |
| | mappings | decimal |
| GAPMCNT | Current global number of address and | Unsigned |
| | port mappings | decimal |
| SAPMCNT | Current subscriber-specific number of | Unsigned |
| | address and port mappings | decimal |
| | | |
| | Specific incoming packet description | |
| | | |
| PSRLM | Packet source realm | Text |
| PATYP | Packet IP address type | "IPv4" or |
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| | | "IPv6" |
| PSADDR | Packet source IP address | IPv4 or |
| | | IPv6 |
| | | address |
| PDADDR | Packet destination IP address | IPv4 or |
| | | IPv6 |
| | | address |
+------------+-----------------------------------------+------------+
Table 2: Parameters Used In NAT-Related Log Reports
5.2.1. General Encoding Rules
All fields MUST be encoded as 7-bit US ASCII [US-ASCII].
Complete IPv6 addresses MUST be presented according to the rules
specified in Sections 4 and 5 of [RFC5952], without a succeeding
prefix length. The Section 5 rules MUST NOT be applied unless the
address can be distinguished as having an IPv4 address embedded in
the lower 32 bits solely from the IPv6 prefix portion (e.g., based on
well-known prefix, flag), without external information. In such
cases, the IPv6 prefix portion MUST be presented according to the
Section 4 rules. Stand-alone IPv6 prefixes (i.e., outside of special
addresses) MUST be presented according to the Section 4 rules, with
the slash character (/) appended, followed by a decimal value with
leading zeroes suppressed, giving the prefix length (0 to 127) in
bits.
Similarly, complete IPv4 addresses MUST be presented in dotted
decimal format, with no succeeding prefix length. IPv4 prefixes MUST
be presented as if they were full addresses, with the slash character
(/) appended, followed by a decimal value with leading zeroes
suppressed, giving the prefix length (0 to 31) in bits.
N-bit fields and unsigned decimals are both presented as unsigned
decimal integers with no leading zeroes.
5.2.2. Special Cases
Three special cases are identified in Table 2: encoding of the
interface index list (PARAM-NAMEs SIFIX and DIFIX), encoding of the
VPN identifier (PARAM-NAMEs SVPN and DVPN), and encoding of the
trigger for resource allocation events (PARAM-NAME TRIG).
The interface index list is presented as a series of individual
interface indexes separated by commas, e.g., SIFIX="5,15". Each
individual interface index is presented as a 32-bit field (i.e., as
an unsigned decimal integer with no leading zeroes).
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The VPN Identifier is standardized in [RFC2685], and consists of a
three octet VPN Authority (Organizationally Unique Identifier, OUI)
followed by a four octet VPN index identifying the VPN according to
OUI. For SYSLOG, the OUI portion is presented as a string of six
hexadecimal digits in lower case. The VPN index is presented as a
32-bit field. A colon (:) is used to separate the OUI from the
succeeding index value. The OUI and separator MAY be omitted. If
so, the applicable OUI is the default value for the NAT instance.
The trigger is an enumeration of text values which were not spelled
out in the table itself for lack of space. The possible values for
TRIG are:
"OPKT": outgoing packet received at NAT.
"IPKT": incoming packet received at NAT.
"ADMIN": administrative action.
"APMDEL": deletion of the underlying address and port mapping.
"AMDEL": deletion of the underlying address mapping.
"AUTO": autonomous action of the NAT.
The values applicable for any specific event are a subset of this
list and are spelled out for each event in Section 5.3.
5.2.3. Relationship To Objects In the NAT MIB
Table 3 lists the parameters in the same order as Table 2 and relates
each parameter to its corresponding object in the NAT MIB.
+------------------------+------------------------------------------+
| PARAM-NAME | Related MIB Object(s) |
+------------------------+------------------------------------------+
| Miscellaneous | |
| | |
| NATINST | natInstanceAlias in natInstanceTable |
| TRIG | None |
| | |
| Subscriber-identifying | |
| information | |
| | |
| SSUBIX | natSubscriberIndex in |
| | natSubscribersTable |
| SIFIX | natSubsInterfaceIndex in |
| | natSubsInterfaceIdentifierTable |
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| SVLAN | natSubscriberVlanIdentifier in |
| | natSubscribersTable |
| SVPN | natSubscriberVpnIdentifier in |
| | natSubscribersTable |
| SV6ENC | natSubscriberIPEncapsIdType and |
| | natSubscriberIPEncapsIdAddr in |
| | natSubscribersTable |
| DSUBIX | natSubscriberIndex in |
| | natSubscribersTable |
| DIFIX | natSubsInterfaceIndex in |
| | natSubsInterfaceIdentifierTable |
| DVLAN | natSubscriberVlanIdentifier in |
| | natSubscribersTable |
| DVPN | natSubscriberVpnIdentifier in |
| | natSubscribersTable |
| DV6ENC | natSubscriberIPEncapsIdType and |
| | natSubscriberIPEncapsIdAddr in |
| | natSubscribersTable |
| | |
| Internal packet | |
| description | |
| | |
| IRLM | natSubscriberRealm in |
| | natSubscribersTable |
| IATYP | natMapIntAddrIntType in |
| | natMapIntAddrTable or |
| | natMappingIntAddressType in |
| | natMappingTable |
| ISADDR | natMapIntAddrInt in natMapIntAddrTable |
| | or natMappingIntAddress in |
| | natMappingTable |
| ISPORT | natMappingIntPort in natMappingTable |
| IDADDR | None |
| IDPORT | None |
| PROTO | natMappingProto in natMappingTable |
| | |
| External (mapped) | |
| packet description | |
| | |
| XRLM | natPoolRealm in natPoolTable |
| XATYP | natMapIntAddrExtType in |
| | natMapIntAddrTable or |
| | natMappingExtAddressType in |
| | natMappingTable |
| XSADDR | natMapIntAddrExt in natMapIntAddrTable |
| | or natMappingExtAddress in |
| | natMappingTable |
| XSPORT | natMappingExtPort in natMappingTable |
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| XDADDR | None |
| XDPORT | None |
| | |
| Port range description | |
| | |
| PORTMN | None |
| PORTMX | None |
| | |
| Values related to | |
| thresholds | |
| | |
| POOLID | natPoolIndex in natPoolTable |
| POOLHW | natPoolWatermarkHigh in natPoolTable |
| POOLLW | natPoolWatermarkLow in natPoolTable |
| GAMCNT | natAddressMappingCreations - |
| | natAddressMappingRemovals in |
| | natCountersTable |
| GAPMCNT | natMappingCreations - natMappingRemovals |
| | in natCountersTable |
| SAPMCNT | natSubscriberMappingCreations - |
| | natSubscriberMappingRemovals in |
| | natSubscribersTable |
| | |
| Specific incoming | |
| packet description | |
| | |
| PSRLM | natSubscriberRealm in |
| | natSubscribersTable in the case of a |
| | packet originated by an identifiable |
| | subscriber |
| PATYP | None |
| PSADDR | None |
| PDADDR | None |
+------------------------+------------------------------------------+
Table 3: Relationship of Parameters To Objects In the NAT MIB
5.3. Encoding Of Complete Log Report For Each Event Type
This section describes the complete NAT-related contents of the logs
used to report the events listed in Table 1.
5.3.1. Encoding of Events Relating To Allocation Of Resources To Hosts
As indicated in Section 5.1, the event reports specified in this
section MUST have APP-NAME="NAT" in the message header.
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5.3.1.1. NAT Address Mapping Creation and Deletion
As shown in Table 1:
o NAT address mapping creation event is indicated by MSGID set to
"AMADD";
o NAT address mapping deletion event is indicated by MSGID set to
"AMDEL".
For both events, the associated SD-ELEMENT is tagged by SD-ID
"namap". The contents of the namap SD-ELEMENT are shown in Table 4.
The requirements for these contents are derived from the description
in Section 3.1.1.
+------------------------------------+----------------+-------------+
| Description | PARAM-NAME | Requirement |
+------------------------------------+----------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Source subscriber index | SSUBIX | MANDATORY |
| Additional source subscriber | One of SIFIX, | CONDITIONAL |
| classifier value as recognized at | SVLAN, SVPN, | |
| the ingress to the internal realm | or SV6ENC | |
| Internal realm | IRLM | CONDITIONAL |
| Internal address type | IATYP | MANDATORY |
| Internal source IP address | ISADDR | MANDATORY |
| External realm | XRLM | CONDITIONAL |
| External address type | XATYP | MANDATORY |
| External source IP address | XSADDR | MANDATORY |
| Trigger for address mapping | TRIG | OPTIONAL |
| creation or deletion | | |
+------------------------------------+----------------+-------------+
Table 4: Contents Of the SD-ELEMENT Section For Logging the Address
Mapping Creation and Deletion Events
Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
o One of SIFIX, SVLAN, SVPN, or SV6ENC REQUIRED if the internal
source IP address is not enough to identify the subscriber
unambiguously, else MUST NOT appear.
o IRLM or XRLM REQUIRED if not the default internal or external
realm, respectively, else MAY appear.
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For the AMADD event type (MSGID), TRIG can take on the values "OPKT"
or "ADMIN". For the AMDEL event type, TRIG can take on the values
"ADMIN" or "AUTO".
Example: DS-Lite AFTR. One NAT instance. Multiple internal IPv4
realms containing the subscribers, divided by higher-level IPv6
prefix (details unnecessary). One default global IPv4 external
realm. Intra-subscriber sessions use mappings into this realm.
Subscriber A in realm Internal05 sends an outgoing packet, causing
the creation of an address mapping from the DS-Lite well-known
address 192.0.0.2 to the global IPv4 address 198.51.100.127.
Subscriber A's encapsulating IPv6 tunnel address is
2001:db8:a5e6:39b0:bd6a:35ad:1d33:6df6.
The event report for the address mapping creation is as follows (line
folded into several for presentation):
<142>1 2013-05-07T22:14:15.03487Z record.example.net NAT 5063
AMADD [namap SSUBIX="489321"
SV6ENC="2001:db8:a5e6:3900:bd6a:35ad:1d33:6df6" IRLM="Internal05"
IATYP="IPv4" ISADDR="192.0.0.2" XATYP="IPv4"
XSADDR="198.51.100.127"
TRIG="OPKT"]
Character count is about 240.
5.3.1.2. NAT Address and Port Mapping Creation and Deletion
As shown in Table 1:
o NAT address and port mapping creation event is indicated by MSGID
set to "APMADD";
o NAT mapping deletion event is indicated by MSGID set to "APMDEL".
For both events, the associated SD-ELEMENT is tagged by SD-ID
"napmap". The contents of the nmap SD-ELEMENT are shown in Table 5.
The requirements for these contents are derived from the description
in Section 3.1.2.
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+------------------------------------+----------------+-------------+
| PARAM-NAME | Description | Requirement |
+------------------------------------+----------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Source subscriber index | SSUBIX | MANDATORY |
| Additional source subscriber | One of SIFIX, | CONDITIONAL |
| classifier value as recognized at | SVLAN, SVPN, | |
| the ingress to the internal realm | or SV6ENC | |
| Internal realm | IRLM | CONDITIONAL |
| Internal address type | IATYP | MANDATORY |
| Internal source IP address | ISADDR | MANDATORY |
| Internal source port or ICMP | ISPORT | MANDATORY |
| identifier | | |
| External realm | XRLM | CONDITIONAL |
| External address type | XATYP | MANDATORY |
| External source IP address | XSADDR | MANDATORY |
| External source port or ICMP | XSPORT | MANDATORY |
| identifier | | |
| Protocol identifier | PROTO | MANDATORY |
| Trigger for address and port | TRIG | OPTIONAL |
| mapping creation or deletion | | |
+------------------------------------+----------------+-------------+
Table 5: Contents Of the SD-ELEMENT Section For Logging the mapping
Creation and Deletion Events
Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
o One of SIFIX, SVLAN, SVPN, or SV6ENC REQUIRED if the internal
source IP address is not enough to identify the subscriber
unambiguously, else MUST NOT appear.
o IRLM or XRLM REQUIRED if not the default internal or external
realm, respectively, else MAY appear.
For the APMADD event type (MSGID), TRIG can take on the values
"OPKT", IPKT", or "ADMIN".
Note: it is not clear how the internal source port is selected if
an address and port mapping is triggered by an incoming TCP
packet. The NAT could select one based on its knowledge of
subscriber port usage, but this knowledge may be incomplete. Some
type of negotiation may be necessary, or else TCP address and port
mappings can only be triggered by outbound packets as in the
example below.
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For the APMDEL event type, TRIG can take on the values "ADMIN",
"AMDEL", or "AUTO".
Example: The triggering outgoing packet in the previous case was a
TCP packet with internal source port 49178. As well as triggering
the creation of an address mapping, the packet triggers the creation
of an address and port mapping between that port and an external
source port 6803. The corresponding mapping creation report would
look like this:
<142>1 2013-05-07T22:14:15.03487Z record.example.net NAT 5063
APMADD [napmap SSUBIX="489321"
SV6ENC="2001:db8:a5e6:3900:bd6a:35ad:1d33:6df6" IRLM="Internal05"
IATYP="IPv4" ISADDR="192.0.0.2" ISPORT="49178"
XATYP="IPv4" XSADDR="198.51.100.127" XSPORT=6803"
PROTO="6" TRIG="OPKT"]
Character count is about 280.
5.3.1.3. NAT Session Creation and Deletion
As shown in Table 1:
o NAT session creation event is indicated by MSGID set to "SADD";
o NAT session deletion event is indicated by MSGID set to "SDEL".
For both events, the associated SD-ELEMENT is tagged by SD-ID
"nsess". The contents of the nsess SD-ELEMENT are shown in Table 6.
The requirements for these contents are derived from the description
in Section 3.1.3.
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+-------------------------------------+---------------+-------------+
| PARAM-NAME | Description | Requirement |
+-------------------------------------+---------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Source subscriber index | SSUBIX | MANDATORY |
| Additional source subscriber | One of SIFIX, | CONDITIONAL |
| classifier value as recognized at | SVLAN, SVPN, | |
| the ingress to the internal realm | or SV6ENC | |
| Internal realm | IRLM | CONDITIONAL |
| Internal address type | IATYP | MANDATORY |
| Internal source IP address | ISADDR | MANDATORY |
| Internal source port or ICMP | ISPORT | MANDATORY |
| identifier | | |
| External realm | XRLM | CONDITIONAL |
| External address type | XATYP | MANDATORY |
| External source IP address | XSADDR | MANDATORY |
| External source port or ICMP | XSPORT | MANDATORY |
| identifier | | |
| Protocol identifier | PROTO | MANDATORY |
| Internal destination IP address | IDADDR | CONDITIONAL |
| Internal destination port or ICMP | IDPORT | CONDITIONAL |
| identifier | | |
| Destination subscriber index | DSUBIX | CONDITIONAL |
| Additional destination subscriber | One of DIFIX, | CONDITIONAL |
| classifier value as recognized at | DVLAN, DVPN, | |
| the ingress to the external realm | or DV6ENC | |
| External destination IP address | XDADDR | CONDITIONAL |
| External destination port or ICMP | XDPORT | CONDITIONAL |
| identifier | | |
| Trigger for session creation or | TRIG | OPTIONAL |
| deletion | | |
+-------------------------------------+---------------+-------------+
Table 6: Contents Of the SD-ELEMENT Section For Logging the Session
Creation and Deletion Events
Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
o One of SIFIX, SVLAN, SVPN, or SV6ENC REQUIRED if the internal
source IP address is not enough to identify the subscriber
unambiguously, else MUST NOT appear.
o IRLM or XRLM REQUIRED if not the default internal or external
realm, respectively, else MAY appear.
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o IDADDR and IDPORT REQUIRED if destination logging is enabled and
these need to be remapped to external destination address and
port. Otherwise, if destination logging is disabled, they MUST
NOT appear, and if destination logging is enabled, they SHOULD NOT
appear because of redundancy.
o DSUBIX REQUIRED if destination logging is enabled and the
destination is a subscriber served by the NAT, else MUST NOT
appear.
o One of DIFIX, DVLAN, DVPN, or DV6ENC REQUIRED if destination
logging is enabled and the destination is a subscriber served by
the NAT and the external destination address is not enough to
identify the external destination subscriber unambiguously, else
MUST NOT appear.
o XDADDR and XDPORT REQUIRED if destination logging is enabled, else
MUST NOT appear.
For the SADD event type (MSGID), TRIG can take on the values "OPKT",
IPKT", or "ADMIN". For the SDEL event type, TRIG can take on the
values "ADMIN", "MDEL", or "AUTO".
Example: destination logging is enabled. The outgoing packet that
triggered the address and port mapping in the previous section was
sent to 192.0.2.57 port 80. The session creation event report
appears as follows:
<142>1 2013-05-07T22:14:15.03487Z record.example.net NAT 5063
SESSADD [nsess SSUBIX="489321"
SV6ENC="2001:db8:a5e6:3900:bd6a:35ad:1d33:6df6" IRLM="Internal05"
IATYP="IPv4" ISADDR="192.0.0.2" ISPORT="49178"
XATYP="IPv4" XSADDR="198.51.100.127" XSPORT=6803"
PROTO="6" XDADDR="192.0.2.57" XDPORT="80" TRIG="OPKT"]
Character count is about 310.
5.3.1.4. Port Range Allocation and Deallocation
As shown in Table 1:
o Port range allocation event is indicated by MSGID set to "PTADD";
o Port range deallocation event is indicated by MSGID set to
"PTDEL".
For both events, the associated SD-ELEMENT is tagged by SD-ID
"nprng". The contents of the npset SD-ELEMENT are shown in Table 7.
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The requirements for these contents are derived from the description
in Section 3.1.4.
+------------------------------------+----------------+-------------+
| PARAM-NAME | Description | Requirement |
+------------------------------------+----------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Source subscriber index | SSUBIX | MANDATORY |
| Additional source subscriber | One of SIFIX, | CONDITIONAL |
| classifier value as recognized at | SVLAN, SVPN, | |
| the ingress to the internal realm | or SV6ENC | |
| Internal realm | IRLM | CONDITIONAL |
| Internal address type | IATYP | MANDATORY |
| Internal source IP address | ISADDR | MANDATORY |
| External realm | XRLM | CONDITIONAL |
| External address type | XATYP | MANDATORY |
| External source IP address | XSADDR | MANDATORY |
| Port range lowest value | PORTMN | MANDATORY |
| Port range highest value | PORTMX | MANDATORY |
| Trigger for port range allocation | TRIG | OPTIONAL |
| or deallocation | | |
+------------------------------------+----------------+-------------+
Table 7: Contents Of the SD-ELEMENT Section For Logging the Port Set
Allocation and Deallocation Events
Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
o One of SIFIX, SVLAN, SVPN, or SV6ENC REQUIRED if the internal
source IP address is not enough to identify the subscriber
unambiguously, else MUST NOT appear.
o IRLM or XRLM REQUIRED if not the default internal or external
realm, respectively, else MAY appear.
For the PTADD event type (MSGID), TRIG can take on the values "OPKT",
"IPKT", "ADMIN", or "AUTO". For the PTDEL event type, TRIG can take
on the values "ADMIN" or "AUTO".
Consider an example where the range 1024-1535 is allocated to the
address mapping on which the example in Section 5.3.1.1 is based.
The corresponding port range allocation report would look like this:
<142>1 2013-05-07T22:14:15.03487Z record.example.net NAT 5063
PTADD [nprng SSUBIX="489321"
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SV6ENC="2001:db8:a5e6:3900:bd6a:35ad:1d33:6df6" IRLM="Internal05"
IATYP="IPv4" ISADDR="192.0.0.2" XATYP="IPv4"
XSADDR="198.51.100.127"
PORTMN="1024" PORTMX="1535" TRIG="OPKT"]
Character count is about 270.
5.3.2. Encoding of Threshold Events
As indicated in Section 5.1, the event reports specified in this
section MUST have APP-NAME="NATTHR" in the SYSLOG message header.
5.3.2.1. NAT Address Pool High- and Low-Water-Mark Threshold Events
As shown in Table 1:
o NAT address pool high-water-mark threshold event is indicated by
MSGID set to "POOLHT";
o NAT address pool low-water-mark threshold event is indicated by
MSGID set to "POOLLT".
For both events, the associated SD-ELEMENT is tagged by SD-ID
"npool". The contents of the npool SD-ELEMENT are shown in Table 8.
The requirements for these contents are derived from the description
in Section 3.2.1.
+------------------------------+----------------------+-------------+
| PARAM-NAME | Description | Requirement |
+------------------------------+----------------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Pool identifier | POOLID | MANDATORY |
| The threshold value set by | POOLHW or POOLLW as | CONDITIONAL |
| the administrator | applicable | |
+------------------------------+----------------------+-------------+
Table 8: Contents Of the SD-ELEMENT Section For Logging the Address
Pool High- and Low-Water-Mark Threshold Events
Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
o POOLHW REQUIRED for high-water-mark event, else MUST NOT appear.
o POOLLW REQUIRED for low-water-mark event, else MUST NOT appear.
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Example, assuming a high-water-mark threshold of 80% aggregate
address-port utilization::
<132>1 2013-08-15T09:15:16.08716Z record.example.net NATTHR 5025
POOLHT [npool POOLID="13" POOLHW="80"]
Character count is about 105.
5.3.2.2. Global Address Mapping High-Water-Mark Threshold Exceeded
As shown in Table 1:
o Global address mapping high-water-mark threshold event is
indicated by MSGID set to "GAMHT"; and
o the associated SD-ELEMENT is tagged by SD-ID "ngamht".
The contents of the ngamht SD-ELEMENT are shown in Table 9. The
requirements for these contents are derived from the description in
Section 3.2.2.
+---------------------------------------+-------------+-------------+
| PARAM-NAME | Description | Requirement |
+---------------------------------------+-------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Current number of active address | GAMCNT | MANDATORY |
| mappings | | |
+---------------------------------------+-------------+-------------+
Table 9: Contents Of the SD-ELEMENT Section For Logging the Global
Address Map High-Water-Mark Threshold Event
Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
Example, assuming a threshold was set to 690000, already exceeded.
As a result, prior events of this type were detected and logged,
unless they were suppressed by the sort of controls discussed in
Section 6.
<132>1 2013-08-15T09:15:16.08716Z record.example.net NATTHR 5025
GAMHT [ngamht GAMCNT="690015"]
Character count is about 95.
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5.3.2.3. Global Address and Port Mapping High-Water-Mark Threshold
Event
As shown in Table 1:
o Global address and port mapping high-water-mark threshold event is
indicated by MSGID set to "GAPMHT"; and
o the associated SD-ELEMENT is tagged by SD-ID "ngapmht".
The contents of the ngmht SD-ELEMENT are shown in Table 10. The
requirements for these contents are derived from the description in
Section 3.2.3.
+---------------------------------------+-------------+-------------+
| PARAM-NAME | Description | Requirement |
+---------------------------------------+-------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Current global number of address and | GAPMCNT | MANDATORY |
| port mappings | | |
+---------------------------------------+-------------+-------------+
Table 10: Contents Of the SD-ELEMENT Section For Logging the Global
Address and Port Mapping High-Water-Mark Threshold Event
Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
Example: suppose the threshold was set to 2000000, so it has already
been exceeded. As in the previous section, prior events of this type
were detected and logged, unless they were suppressed by the sort of
controls discussed in Section 6.
<132>1 2013-08-15T09:15:16.08716Z record.example.net NATTHR 5025
GAPMHT [ngapmht GAPMCNT="2000023"]
Character count is about 100.
5.3.2.4. Subscriber-Specific Address and Port Mapping High-Water-Mark
Threshold Event
As shown in Table 1:
o Subscriber-specific address and port mapping high-water-mark
threshold event is indicated by MSGID set to "SAPMHT"; and
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o the associated SD-ELEMENT is tagged by SD-ID "nsapmht".
The contents of the nsapmht SD-ELEMENT are shown in Table 11. The
requirements for these contents are derived from the description in
Section 3.2.4.
+---------------------------------------+-------------+-------------+
| PARAM-NAME | Description | Requirement |
+---------------------------------------+-------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Index of the affected subscriber | SSUBIX | MANDATORY |
| Current number of address and port | SAPMCNT | MANDATORY |
| mappings for this subscriber | | |
+---------------------------------------+-------------+-------------+
Table 11: Contents Of the SD-ELEMENT Section For Logging the
Subscriber-Specific Address and Port Mapping High-Water-Mark
Threshold Event
Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
Example: suppose the threshold was set to 1500 and the number of
mappings for this subscriber has been increasing. Then this is the
first threshold-exceeded event detected of what could possibly be a
series of such events until subscriber consumption of outgoing ports
drops below threshold again.
<133>1 2013-08-15T09:15:16.08853Z record.example.net NATTHR 5025
SAPMHT [nsapmht SSUBIX="489321" SAPMCNT="1501"]
Character count is about 115.
5.3.3. Encoding of Limit Events
As indicated in Section 5.1, the event reports specified in this
section MUST have APP-NAME="NATLIM" in the SYSLOG message header.
5.3.3.1. Global Address Mapping Limit Exceeded
As shown in Table 1:
o Global address mapping limit exceeded event is indicated by MSGID
set to "GAMLIM"; and
o the associated SD-ELEMENT is tagged by SD-ID "ngaml".
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The contents of the ngaml SD-ELEMENT are shown in Table 12. The
requirements for these contents are derived from the description in
Section 3.3.1.
+----------------------------------+-------------+-------------+
| PARAM-NAME | Description | Requirement |
+----------------------------------+-------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Index of the affected subscriber | SSUBIX | MANDATORY |
+----------------------------------+-------------+-------------+
Table 12: Contents Of the SD-ELEMENT Section For Logging the Global
Address Map Limit Exceeded Event
Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
Example:
<131>1 2013-08-15T09:15:16.08716Z record.example.net NATLIM 5025
GAMLIM [ngaml NATINST="VRF-Cust-X" SSUBIX="278067"]
Character count is about 115.
5.3.3.2. Global Address and Port Mapping Limit Exceeded
As shown in Table 1:
o Global adress and port mapping limit exceeded event is indicated
by MSGID set to "GAPMLIM"; and
o the associated SD-ELEMENT is tagged by SD-ID "ngapml".
The contents of the ngapml SD-ELEMENT are shown in Table 13. The
requirements for these contents are derived from the description in
Section 3.3.2.
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+---------------------------------------+-------------+-------------+
| PARAM-NAME | Description | Requirement |
+---------------------------------------+-------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Index of the internal subscriber | SSUBIX | CONDITIONAL |
| Index of the external subscriber | DSUBIX | CONDITIONAL |
| Source realm of the triggering packet | PSRLM | MANDATORY |
| Incoming packet header IP address | PATYP | CONDITIONAL |
| type | | |
| Incoming packet source IP address | PSADDR | CONDITIONAL |
+---------------------------------------+-------------+-------------+
Table 13: Contents Of the SD-ELEMENT Section For Logging the Global
Address and Port Mapping Limit Exceeded Event
Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
o SSUBIX REQUIRED if the mapping was triggered by a packet outgoing
from the internal to the external realm, else MUST NOT appear.
o DSUBIX is REQUIRED if the mapping was triggered by a packet
incoming from a subscriber served by the NAT and located in the
external realm (i.e., using an address mapping created previously
by the internal subscriber), else MUST NOT appear.
o PATYP and PSADDR from the initiating packet are REQUIRED if the
mapping was triggered by a packet incoming from a purely external
realm (i.e., using an address mapping created previously by the
internal subscriber), else MAY appear.
Example: limit event triggered by a packet coming from 192.0.2.57 in
realm "externv4".
<131>1 2013-08-15T09:15:16.08716Z record.example.net NATLIM 5025
GAPMLIM [ngapml NATINST="VRF-Cust-X" PSRLM="externv4"
PATYP="IPv4" PSADDR="192.0.2.57"]
Character count is about 150.
5.3.3.3. Global Limit On Number of Active Hosts Exceeded
As shown in Table 1:
o Global active hosts limit exceeded event is indicated by MSGID set
to "GSLIM"; and
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o the associated SD-ELEMENT is tagged by SD-ID "ngsl".
The contents of the ngsl SD-ELEMENT are shown in Table 14. The
requirements for these contents are derived from the description in
Section 3.3.3.
+----------------------------------+-------------+-------------+
| PARAM-NAME | Description | Requirement |
+----------------------------------+-------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Index of the affected subscriber | SSUBIX | MANDATORY |
+----------------------------------+-------------+-------------+
Table 14: Contents Of the SD-ELEMENT Section For Logging the Global
Active Host Limit Exceeded Event
Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
An example would look exactly like that in Section 5.3.3.1 with the
substitution of GSLIM for GAMLIM and ngsl for ngaml.
5.3.3.4. Subscriber-Specific Limit On Number of Address and Port
Mappings Exceeded
As shown in Table 1:
o Subscriber-specific mapping limit exceeded event is indicated by
MSGID set to "SMLIM"; and
o the associated SD-ELEMENT is tagged by SD-ID "nsml".
The contents of the nsml SD-ELEMENT are shown in Table 15. The
requirements for these contents are derived from the description in
Section 3.3.4.
+----------------------------------+-------------+-------------+
| PARAM-NAME | Description | Requirement |
+----------------------------------+-------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Index of the affected subscriber | SSUBIX | MANDATORY |
+----------------------------------+-------------+-------------+
Table 15: Contents Of the SD-ELEMENT Section For Logging the
Subscriber-Specific Mapping Limit Exceeded Event
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Conditions:
o NATINST REQUIRED if device supports more than one instance, else
MAY appear.
An example would look exactly like that in Section 5.3.3.1 with the
substitution of SAPMLIM for GAMLIM and nsapml for ngaml.
5.3.3.5. Pending Fragment Limit Exceeded
As shown in Table 1:
o Pending fragment limit exceeded event is indicated by MSGID set to
"FRAG"; and
o the associated SD-ELEMENT is tagged by SD-ID "nfpkt".
The contents of the nfpkt SD-ELEMENT are shown in Table 16. The
requirements for these contents are derived from the description in
Section 3.3.5.
+-------------------------------+-------------+-------------+
| PARAM-NAME | Description | Requirement |
+-------------------------------+-------------+-------------+
| NAT instance identifier | NATINST | CONDITIONAL |
| Source realm of the packet | PSRLM | MANDATORY |
| Packet header IP address type | PATYP | MANDATORY |
| Packet source IP address | PSADDR | MANDATORY |
| Packet destination IP address | PDADDR | MANDATORY |
| Source subscriber index | SSUBIX | CONDITIONAL |
+-------------------------------+-------------+-------------+
Table 16: Contents Of the SD-ELEMENT Section For Logging the Pending
Fragment Limit Exceeded Event
Conditions:
o NAT instance identifier REQUIRED if device supports more than one
instance, else MAY appear.
o Source subscriber index REQUIRED if the source of the packet is a
subscriber served by the NAT and can be determined, else MUST NOT
appear.
Example: assuming the packet passing the limit came from an internal
host and was dropped as a result of the limit.
<132>1 2013-08-15T09:15:16.08Z record.example.net NATLIM 5025
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FRAG [nfpkt PSRLM="DsLite-089" PATYP="IPv4" PSADDR="192.0.0.2"
PDADDR="203.0.113.26" SSUBIX="32791"]
Character count is about 160.
6. Management Considerations
This section considers requirements for management of the log system
to support logging of the events described above. It first covers
requirements applicable to log management in general. Any additional
standardization required to fulfil these requirements is out of scope
of the present document. Subsequent sub-sections discuss management
issues related to specific event report types. The identifiers PRI,
APP-NAME, and MSGID used below refer to fields in the SYSLOG header
[RFC5424]
6.1. General Requirements For Control Of Logging
This document assumes that any implementation provides the following
capabilities, discussed in more detail below:
o ability to configure the PRI value of each event report type at
the granularity of (APP-NAME, MSGID) combination;
o ability at each collector to determine that event reports that it
should have received have been lost. The required granularity is
at least at the level of PRI and may be finer for some event
types.
o ability to configure criteria to automatically suppress the
generation of event reports while the criteria are met, at the
granularity of (APP-NAME, MSGID) combination.
6.1.1. Configuration of PRI Value
The PRI value is composed of two numbers, the Facility value and the
Severity. It may be used at the origin for selecting logs to streams
being dispatched to different collectors, and in applications beyond
the collectors to prioritize display of logs to operators. The event
reports in this document have been structured such that the Severity
level varies between event types as represented by (APP-NAME, MSGID)
combination. As an extreme example, the address pool high-water-mark
threshold event (APP-NAME="NATTHR", MSGID="POOLHT") is obviously more
urgent than the low-water-mark threshold event (APP-NAME="NATTHR",
MSGID="POOLLT").
To some extent, this document tries to simplify message routing by
making a general distinction between event types recording the
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allocation of resources to hosts (with APP-NAME="NAT") and events of
interest to operations and maintenance (with APP-NAME="NATTHR" and
APP-NAME="NATLIM"). The need to provide different Severity levels
for different event types remains.
6.1.2. Ability For Each Collector To Detect Lost Event Reports
Operators have a need to know when a given collector has not received
all of the event reports it should have. It probably does not matter
if less-important events are tracked at the granularity of event type
(APP-NAME, MSGID combination), by APP-NAME, or just by PRI value.
The event types defined in this document relating to allocation of
resources to hosts are a special case. Regulatory requirements or
the possibility that such reports might be introduced into court in
cases such as abuse impose a requirement that the record of
allocations to a particular host be complete. This requirement is
important enough to be stated in the Security Considerations section
(Section 7), where the implementation of signed SYSLOG messages
[RFC5848], which also provides message sequencing, is mandated as
part of this specification.
In deploying [RFC5848], the operator needs to decide the level of
granularity of tracking, whether it should be over the whole set of
reports covered by APP-NAME="NAT" or at a finer level. This
judgement has to be tempered by local circumstances. One point to
note is that since both creations/allocations and deletions/
deallocations are recorded, a certain amount of redundancy is
available in the reports being generated. However, without both the
creation and deletion timestamps, there is no definitive evidence of
the specific period of time during which the resources concerned were
allocated to a specific host.
6.1.3. Ability To Rate Limit Or Disable Event Reports
The event report types specified with APP-NAME="NATTHR" and APP-
NAME="NATLIM" all relate to thresholds or limits. By their nature,
events of this sort will come in bursts. The threshold or limit will
be hit, the resource concerned will remain busy for a period, then
pressure on the resource will ease. Depending on the resource,
possibly hundreds of instances of the event concerned will be
detected during a single busy period.
Where repeated events involve the same resource, it makes little
sense to report all of them, since the NAT MIB counters provide the
necessary information more succinctly. On the other hand, it can be
useful to know that the fragmentation limit, for instance, is being
hit by successive packets from the same source address.
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As a result of these considerations, this document requires that
implementations MUST provide means to configure limits on the rate at
which event reports of a given type (APP-NAME, MSGID combination) are
generated. It is RECOMMENDED that it be possible to specify two
values per (APP-NAME, MSGID) combination:
o minimum time between initial instances of a given event report
type;
o maximum number of instances of the event report to generate per
busy period.
Regardless of the detailed method the implementation provides for
specifying the rate limiting of individual event report types, all
implementations MUST allow the operator to indicate through
configuration that a given event report type is to be completely
disabled. This is particularly required to disable logging of either
session or mapping creations and deletions when not required (see
discussion in Section 3.1.2). It is also required when the operator
prefers to receive threshold event notifications via SNMP rather than
SYSLOG.
The ability to rate limit or disable event reports MUST NOT interfere
with the requirement to detect lost messages. This has implications
for any sequence numbering used for that purpose. It is RECOMMENDED
in any event that the implementation provide MIB counters of numbers
of messages not generated due to rate limiting by event type
supported. If this is done, counters for disabled event report types
SHOULD NOT be incremented, since that could require keeping
unnecessary additional state.
6.2. Setting Limits and Thresholds
The "NATTHR" and "NATLIM" events specified in this document depend on
the thresholds and limits configured in the NAT MIB
[I-D.behave-NAT-MIB]. The limits have to do with policy in some
cases (e.g., most especially the subscriber-specific limits), but
generally depend on the implementation and the device in which it is
deployed.
The purpose of high-water-mark thresholds is, of course, to give
sufficient advance warning that utilization of a particular resource
is approaching its limit, so that appropriate provisioning or
reconfiguration action can be undertaken to preserve target service
levels on the NAT device. Thus the following general principles
apply:
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o A high-water-mark threshold should be derived as a percentage of
the relevant limit.
o The more quickly that utilization of a given resource can build
up, the lower the threshold must be to provide an adequate
response time.
o Some limits are more important than others in terms of their
effect on overall service levels provided by the NAT device. To
focus attention on the more important limits, their corresponding
thresholds should be set lower than those for less-important
limits, all other things being equal.
In practice, thresholds will require tuning to fit the particular
characteristics of the NAT device and its users.
The setting of the high-water-mark-thresholds for address pools
(Section 3.2.1) poses additional challenges. The problem is that the
bottleneck for port availability will generally be a single protocol,
which may vary from one time to another. However, the threshold is
based on overall port utilization. If port usage is such that one
protocol generally predominates, the required threshold value has to
be lower than if usage is more balanced between protocols. Clearly
the appropriate threshold value depends on the characteristics of the
traffic handled by the particular address pool concerned.
Pooling behaviour adds another factor for consideration. With a
pooling behaviour of "arbitrary" [RFC4787], port utilization for the
bottleneck protocol can be quite high before service levels offered
by the pool are in danger. On the other hand, with a pooling
behaviour of "paired", possible utilization levels will be much lower
because typically a number of port values will be reserved to each
address mapping and only some of those will be in use on the average.
The difference between "arbitrary" and "paired" utilization for a
given level of service may be quite dramatic.
6.3. Other Management Requirements
The identification of internal realms is contingent on the the
existence and applicability of default internal and external realms.
If the implementation is capable of supporting more than one internal
or external realm, it MUST provide the means for the operator to
specify which realm is the default internal and/or external realm, as
the case may be.
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7. Security Considerations
When logs are being recorded for regulatory reasons or as potential
evidence in abuse cases, preservation of their integrity and
authentication of their origin is essential. To achieve this result,
signed SYSLOG messages [RFC5848] MUST be implemented as part of this
specification. It is RECOMMENDED that the operator deploy [RFC5848]
where local requirements on integrity and authentication of origin
are stringent. In conjunction with [RFC5848] and as recommended in
Section 3 of that document, TLS transport as specified in [RFC5425]
SHOULD be used between the origin and the collector(s) and MUST be
implemented. Section 5.2.1 of [RFC5848] specifies the minimum
support for Key Blob Type that must be provided by implementations of
that specification.
Access to the logs defined in Section 3.1 and Section 5.3.1 while the
reported assignments are in force could improve an attacker's chance
of hijacking a session through port-guessing. Even after an
assignment has expired, the information in the logs SHOULD be treated
as confidential, since, if revealed, it could help an attacker trace
sessions back to a particular user or user location. It is therefore
RECOMMENDED that these logs be transported securely, using [RFC5425],
for example, even if [RFC5848] is not deployed, that they be stored
securely at the collector, and that access to them at the collector
and in applications be tightly controlled.
The logs defined in Section 3.2 and Section 3.3 are less sensitive in
general, but since many of them contain the subscriber identifier,
they could be used to get some sense of subscriber activity. The
fragmentation limit event provides actual packet header contents.
Operators SHOULD at the least deploy secure transport to ensure that
this information is not misused.
8. IANA Considerations
This document requests IANA to make the following assignments to the
SYSLOG Structured Data ID Values registry. RFCxxxx refers to the
present document when approved.
Some PARAM-NAMES appear under more than one SD-ID in Table 17.
Formally, a parameter used with more than one event is registered as
multiple separate parameters, one for each event report in which it
is used. However, there is no reason to change either the PARAM-NAME
or the encoding of the PARAM-VALUE between different instances of the
same parameter if the parameters have the same meaning in both event
reports.
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While a number of parameters are marked CONDITIONAL in the body of
this document, the SYSLOG registry provides only for MANDATORY and
OPTIONAL parameters. All CONDITIONAL parameters have been placed in
the OPTIONAL category in Table 17.
+----------------+--------------------+-----------------+-----------+
| Structured | Structured Data | Required or | Reference |
| Data ID | Parameter | Optional | |
+----------------+--------------------+-----------------+-----------+
| namap | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | SSUBIX | MANDATORY | RFCxxxx |
| | SIFIX | OPTIONAL | RFCxxxx |
| | SVLAN | OPTIONAL | RFCxxxx |
| | SVPN | OPTIONAL | RFCxxxx |
| | SV6ENC | OPTIONAL | RFCxxxx |
| | IRLM | OPTIONAL | RFCxxxx |
| | IATYP | MANDATORY | RFCxxxx |
| | ISADDR | MANDATORY | RFCxxxx |
| | XRLM | OPTIONAL | RFCxxxx |
| | XATYP | MANDATORY | RFCxxxx |
| | XSADDR | MANDATORY | RFCxxxx |
| | TRIG | OPTIONAL | RFCxxxx |
| ---- | ---- | ---- | ---- |
| napmap | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | SSUBIX | MANDATORY | RFCxxxx |
| | SIFIX | OPTIONAL | RFCxxxx |
| | SVLAN | OPTIONAL | RFCxxxx |
| | SVPN | OPTIONAL | RFCxxxx |
| | SV6ENC | OPTIONAL | RFCxxxx |
| | IRLM | OPTIONAL | RFCxxxx |
| | IATYP | MANDATORY | RFCxxxx |
| | ISADDR | MANDATORY | RFCxxxx |
| | ISPORT | MANDATORY | RFCxxxx |
| | XRLM | OPTIONAL | RFCxxxx |
| | XATYP | MANDATORY | RFCxxxx |
| | XSADDR | MANDATORY | RFCxxxx |
| | XSPORT | MANDATORY | RFCxxxx |
| | PROTO | MANDATORY | RFCxxxx |
| | TRIG | OPTIONAL | RFCxxxx |
| ---- | ---- | ---- | ---- |
| nsess | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | SSUBIX | MANDATORY | RFCxxxx |
| | SIFIX | OPTIONAL | RFCxxxx |
| | SVLAN | OPTIONAL | RFCxxxx |
| | SVPN | OPTIONAL | RFCxxxx |
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| | SV6ENC | OPTIONAL | RFCxxxx |
| | IRLM | OPTIONAL | RFCxxxx |
| | IATYP | MANDATORY | RFCxxxx |
| | ISADDR | MANDATORY | RFCxxxx |
| | ISPORT | MANDATORY | RFCxxxx |
| | XRLM | OPTIONAL | RFCxxxx |
| | XATYP | MANDATORY | RFCxxxx |
| | XSADDR | MANDATORY | RFCxxxx |
| | XSPORT | MANDATORY | RFCxxxx |
| | PROTO | MANDATORY | RFCxxxx |
| | IDADDR | OPTIONAL | RFCxxxx |
| | IDPORT | OPTIONAL | RFCxxxx |
| | DSUBIX | OPTIONAL | RFCxxxx |
| | DIFIX | OPTIONAL | RFCxxxx |
| | DVLAN | OPTIONAL | RFCxxxx |
| | DVPN | OPTIONAL | RFCxxxx |
| | DV6ENC | OPTIONAL | RFCxxxx |
| | XDADDR | OPTIONAL | RFCxxxx |
| | XDPORT | OPTIONAL | RFCxxxx |
| | TRIG | OPTIONAL | RFCxxxx |
| ---- | ---- | ---- | ---- |
| nprng | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | SSUBIX | MANDATORY | RFCxxxx |
| | SIFIX | OPTIONAL | RFCxxxx |
| | SVLAN | OPTIONAL | RFCxxxx |
| | SVPN | OPTIONAL | RFCxxxx |
| | SV6ENC | OPTIONAL | RFCxxxx |
| | IRLM | OPTIONAL | RFCxxxx |
| | IATYP | MANDATORY | RFCxxxx |
| | ISADDR | MANDATORY | RFCxxxx |
| | XRLM | OPTIONAL | RFCxxxx |
| | XATYP | MANDATORY | RFCxxxx |
| | XSADDR | MANDATORY | RFCxxxx |
| | PORTMN | MANDATORY | RFCxxxx |
| | PORTMX | MANDATORY | RFCxxxx |
| | TRIG | OPTIONAL | RFCxxxx |
| ---- | ---- | ---- | ---- |
| npool | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | POOLID | MANDATORY | RFCxxxx |
| | POOLLT | OPTIONAL | RFCxxxx |
| | POOLHT | OPTIONAL | RFCxxxx |
| ---- | ---- | ---- | ---- |
| ngamht | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | GAMCNT | MANDATORY | RFCxxxx |
| ---- | ---- | ---- | ---- |
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| ngapmht | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | GAPMCNT | MANDATORY | RFCxxxx |
| ---- | ---- | ---- | ---- |
| nsapmht | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | SSUBIX | MANDATORY | RFCxxxx |
| | SAPMCNT | MANDATORY | RFCxxxx |
| ---- | ---- | ---- | ---- |
| ngaml | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | SSUBIX | MANDATORY | RFCxxxx |
| ---- | ---- | ---- | ---- |
| ngapml | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | SSUBIX | OPTIONAL | RFCxxxx |
| | DSUBIX | OPTIONAL | RFCxxxx |
| | PSRLM | MANDATORY | RFCxxxx |
| | PATYP | OPTIONAL | RFCxxxx |
| | PSADDR | OPTIONAL | RFCxxxx |
| ---- | ---- | ---- | ---- |
| ngsl | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | SSUBIX | MANDATORY | RFCxxxx |
| ---- | ---- | ---- | ---- |
| nsapml | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | SSUBIX | MANDATORY | RFCxxxx |
| ---- | ---- | ---- | ---- |
| nfpkt | | OPTIONAL | RFCxxxx |
| | NATINST | OPTIONAL | RFCxxxx |
| | PSRLM | MANDATORY | RFCxxxx |
| | PATYP | MANDATORY | RFCxxxx |
| | PSADDR | MANDATORY | RFCxxxx |
| | PDADDR | MANDATORY | RFCxxxx |
| | SSUBIX | OPTIONAL | RFCxxxx |
+----------------+--------------------+-----------------+-----------+
Table 17: NAT-Related STRUCTURED-DATA Registrations
9. References
9.1. Normative References
[I-D.behave-NAT-MIB]
Perreault, S., Tsou, T., and S. Sivakumar, "Additional
Managed Objects for Network Address Translators (NAT)
(Work in progress)", September 2013.
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[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address
Translator (NAT) Terminology and Considerations", RFC
2663, August 1999.
[RFC2685] Fox, B. and B. Gleeson, "Virtual Private Networks
Identifier", RFC 2685, September 1999.
[RFC2863] McCloghrie, K. and F. Kastenholz, "The Interfaces Group
MIB", RFC 2863, June 2000.
[RFC4265] Schliesser, B. and T. Nadeau, "Definition of Textual
Conventions for Virtual Private Network (VPN) Management",
RFC 4265, November 2005.
[RFC4363] Levi, D. and D. Harrington, "Definitions of Managed
Objects for Bridges with Traffic Classes, Multicast
Filtering, and Virtual LAN Extensions", RFC 4363, January
2006.
[RFC4784] Carroll, C. and F. Quick, "Verizon Wireless Dynamic Mobile
IP Key Update for cdma2000(R) Networks", RFC 4784, June
2007.
[RFC4787] Audet, F. and C. Jennings, "Network Address Translation
(NAT) Behavioral Requirements for Unicast UDP", BCP 127,
RFC 4787, January 2007.
[RFC5424] Gerhards, R., "The Syslog Protocol", RFC 5424, March 2009.
[RFC5425] Miao, F., Ma, Y., and J. Salowey, "Transport Layer
Security (TLS) Transport Mapping for Syslog", RFC 5425,
March 2009.
[RFC5848] Kelsey, J., Callas, J., and A. Clemm, "Signed Syslog
Messages", RFC 5848, May 2010.
[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
Address Text Representation", RFC 5952, August 2010.
[RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
Algorithm", RFC 6145, April 2011.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, April 2011.
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[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, August 2011.
[US-ASCII]
American National Standards Institute, , "Coded Character
Set -- 7-bit American Standard Code for Information
Interchange", ANSI X3.4, 1986.
9.2. Informative References
[I-D.behave-ipfix-nat-logging]
Sivakumar, S. and R. Penno, "IPFIX Information Elements
for logging NAT Events (Work in progress)", August 2013.
[I-D.pcp-port-set]
Sun, Q., Boucadair, M., Sivakumar, S., Zhou, C., Tsou, T.,
and S. Perreault, "Port Control Protocol (PCP) Extension
for Port Set Allocation (Work in progress)", July 2013.
[I-D.softwire-lw4over6]
Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
Farrer, "Lightweight 4over6: An Extension to the DS-Lite
Architecture (Work in progress)", July 2013.
[I-D.softwire-map]
Troan, O., Dec, W., Li, X., Bao, C., Matsushima, S.,
Murakami, T., and T. Taylor, "Mapping of Address and Port
with Encapsulation (MAP) (Work in progress)", August 2013.
[I-D.tsou-behave-natx4-log-reduction]
Tsou, T., Li, W., and T. Taylor, "Port Management To
Reduce Logging In Large-Scale NATs (Work in progress)",
July 2013.
[RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network
Address Translator (Traditional NAT)", RFC 3022, January
2001.
[RFC4026] Andersson, L. and T. Madsen, "Provider Provisioned Virtual
Private Network (VPN) Terminology", RFC 4026, March 2005.
[RFC5382] Guha, S., Biswas, K., Ford, B., Sivakumar, S., and P.
Srisuresh, "NAT Behavioral Requirements for TCP", BCP 142,
RFC 5382, October 2008.
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[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification", RFC
5969, August 2010.
[RFC6264] Jiang, S., Guo, D., and B. Carpenter, "An Incremental
Carrier-Grade NAT (CGN) for IPv6 Transition", RFC 6264,
June 2011.
[RFC6674] Brockners, F., Gundavelli, S., Speicher, S., and D. Ward,
"Gateway-Initiated Dual-Stack Lite Deployment", RFC 6674,
July 2012.
[RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
2013.
[RFC6888] Perreault, S., Yamagata, I., Miyakawa, S., Nakagawa, A.,
and H. Ashida, "Common Requirements for Carrier-Grade NATs
(CGNs)", BCP 127, RFC 6888, April 2013.
[RFC7011] Claise, B., Trammell, B., and P. Aitken, "Specification of
the IP Flow Information Export (IPFIX) Protocol for the
Exchange of Flow Information", STD 77, RFC 7011, September
2013.
[RFC7040] Cui, Y., Wu, J., Wu, P., Vautrin, O., and Y. Lee, "Public
IPv4-over-IPv6 Access Network", RFC 7040, November 2013.
Authors' Addresses
Zhonghua Chen
China Telecom
P.R. China
Email: 18918588897@189.cn
Cathy Zhou
Huawei Technologies
Bantian, Longgang District
Shenzhen 518129
P.R. China
Email: cathy.zhou@huawei.com
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Tina Tsou
Huawei Technologies
Bantian, Longgang District
Shenzhen 518129
P.R. China
Email: tina.tsou.zouting@huawei.com
T. Taylor (editor)
Huawei Technologies
Ottawa
Canada
Email: tom.taylor.stds@gmail.com
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