Behave S. Sivakumar Internet-Draft Cisco Systems Intended status: Informational R. Penno Expires: April 26, 2012 Juniper Networks October 24, 2011 Logging of NAT Events draft-sivakumar-behave-nat-logging-03 Abstract Carrier grade NAT (CGN) devices are required to log events like creation and deletion of translations and information about the resources it is managing. The logs are required in many cases to identify an attacker or a host that was used to launch malicious attacks and/or for various other purposes of accounting. Since there is no standard way of logging this information, different NAT devices behave differently and hence it is difficult to expect a consistent behavior. 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. 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 April 26, 2012. Copyright Notice Copyright (c) 2011 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 Sivakumar & Penno Expires April 26, 2012 [Page 1] Internet-Draft Logging of NAT Events October 2011 (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect 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. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Event based logging . . . . . . . . . . . . . . . . . . . . . 4 4.1. Information Elements . . . . . . . . . . . . . . . . . . . 4 4.2. Definition of NAT Events . . . . . . . . . . . . . . . . . 6 4.3. Templates for NAT Events . . . . . . . . . . . . . . . . . 6 4.3.1. NAT44 create and delete session event . . . . . . . . 6 4.3.2. NAT64 create and delete session event . . . . . . . . 7 4.3.3. NAT44 BIB create and delete event . . . . . . . . . . 8 4.3.4. NAT64 BIB create and delete event . . . . . . . . . . 8 4.3.5. DS-Lite Session Create and Delete Event . . . . . . . 8 4.3.6. DS-Lite BIB Create and Delete Event . . . . . . . . . 9 4.3.7. PCP MAP Create and Delete Event . . . . . . . . . . . 10 4.3.8. PCP PEER Create and Delete Event . . . . . . . . . . . 10 4.3.9. Addresses Exhausted event . . . . . . . . . . . . . . 11 4.3.10. Ports Exhausted event . . . . . . . . . . . . . . . . 11 4.3.11. Quota exceeded . . . . . . . . . . . . . . . . . . . . 11 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . . 12 8.2. Informative References . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Sivakumar & Penno Expires April 26, 2012 [Page 2] Internet-Draft Logging of NAT Events October 2011 1. Terminology The usage of the term "NAT device" in this document refer to any NAT44, Firewall and NAT64 devices. The usage of the term "collector" refers to any device that receives the binary data from a NAT device and converts that into meaningful information. This document uses the term "Session" as it is defined in [RFC2663] and the term BIB as it is defined in [RFC6146] 2. Introduction This document details the Information Elements(IEs) that are required to be logged by a NAT device. The document will specify the formats of each and every field that are required to be logged by every NAT device and all the optional fields. The fields specified in this document are gleaned from [RFC4787] and [RFC5382]. 2.1. Requirements Language 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 [RFC2119]. 3. Scope This document provides the information model to be used for logging the Carrier Grade NAT (CGN) events. This document does not provide guidance on the transport protocol that is to be used to log NAT events. The log events SHOULD NOT be lost but the choice of the actual transport protocol is beyond the scope of this document. The existing IANA IPFIX Information Elements registry [IPFIX-IANA] already has assignments for many NAT logging events. For convenience, this document uses those same Information Elements. However, as stated earlier, this document is not defining IPFIX or Netflow 9 as the framework for logging. Rather, the information contained in these elements is within the scope of this document. This document assumes that the NAT device will use some existing framework like IPFIX, Netflow version 9, etc to send the log events to the collector. But it is beyond the scope of the document to define the framework to be used for logging. However, the framework should support specifying a template that the NAT device will use to send its events. The templates can be of varying length and there could be multiple templates that a NAT device could use to log the events. This document provides IPFIX IEs as examples as most of the Sivakumar & Penno Expires April 26, 2012 [Page 3] Internet-Draft Logging of NAT Events October 2011 IEs defined for NAT event logging are already allocated by IANA in the IPFIX registry. The implementation details of the collector application is beyond the scope of this document. The optimization of logging the NAT events are left to the implementation and are beyond the scope of this document. 4. Event based logging An event in a NAT device can be viewed as a happening as it relates to the management of NAT resources. The creation and deletion of NAT sessions and bindings are examples of events as it results in the resources (addresses and ports) being allocated or freed. The events can happen either through the processing of data packets flowing through the NAT device or through an external entity installing policies on the NAT router. The list of events are provided in Section 4.1. Each of these events SHOULD be logged, unless they are administratively prohibited. A NAT device MAY log these events to multiple collectors if redundancy is required. The network administrator will specify the collectors to which the log records are to be sent. Prior to logging any events, the NAT device MUST send the template of the record to the collector to declare the format of the data record that it is using to send the events. The templates can be exchanged as frequently as required given the reliability of the connection. NAT device SHOULD combine as many events as possible in a single packet to effectively utilize the network bandwidth. 4.1. Information Elements The templates could contain a subset of the Information Elements(IEs) shown in Table 1 depending upon the event being logged. For example a NAT44 session creation template record will contain, {sourceIPv4Adress, postNATSourceIPv4Address, destinationIpv4Address, postNATDestinationIPv4Address, sourceTransportPort, postNAPTSourceTransportPort, destinationTransportPort, postNAPTDestTransportPort, natOriginatingAddressRealm, natEvent, timeStamp} An example of the actual event data record is shown below - in a readable form {192.168.16.1, 201.1.1.100, 207.85.231.104, 207.85.231.104, 14800, Sivakumar & Penno Expires April 26, 2012 [Page 4] Internet-Draft Logging of NAT Events October 2011 1024, 80, 80, 0, 1, 09:20:10:789} A single NAT device could be exporting multiple templates and the collector should support receiving multiple templates from the same source. +----------------------------------+--------+-----------------------+ | Field Name | Size | Description | | | (bits) | | +----------------------------------+--------+-----------------------+ | timeStamp | 64 | System Time when the | | | | event occured. | | sourceIPv4Address | 32 | Source IPv4 Address | | postNATSourceIPv4Address | 32 | Translated Source | | | | IPv4 Address | | protocolIdentifier | 8 | Transport protocol | | sourceTransportPort | 16 | Source Port | | postNAPTsourceTransportPort | 16 | Translated Source | | | | port | | destinationIPv4Address | 32 | Destination IPv4 | | | | Address | | postNATDestinationIPv4Address | 32 | Translated IPv4 | | | | destination address | | destinationTransportPort | 16 | Destination port | | postNAPTdestinationTransportPort | 16 | Translated | | | | Destination port | | sourceIPv6Address | 128 | Source IPv6 address | | destinationIPv6Address | 128 | Destination IPv6 | | | | address | | postNATSourceIPv6Address | 128 | Translated source | | | | IPv6 addresss | | postNATDestinationIPv6Address | 128 | Translated | | | | Destination IPv6 | | | | address | | natOriginatingAddressRealm | 8 | Address Realm | | natEvent | 8 | Type of Event | | postNATPortBlockStart | 16 | Allocated port block | | | | start | | postNATPortBlockEnd | 16 | Allocated Port block | | | | end | | ipv6Prefix | 128 | IPv6 prefix in | | | | DS-lite | | srcMacAddress | 48 | MAC address in case | | | | of L2 NAT | | vlanId | 16 | VLAN ID in case of | | | | overlapping networks | Sivakumar & Penno Expires April 26, 2012 [Page 5] Internet-Draft Logging of NAT Events October 2011 | ingressVRFID | 32 | VRF ID in case of | | | | overlapping networks | +----------------------------------+--------+-----------------------+ Table 1: Template format Table 4.2. Definition of NAT Events The following are the list of NAT events and the proposed event values. The list can be expanded in the future as necessary. The data record will have the corresponding natEvent value to identify the event being logged. +-------------------------+--------+ | Event Name | Values | +-------------------------+--------+ | NAT44 Session create | 1 | | NAT44 Session delete | 2 | | NAT64 Session create | 3 | | NAT64 Session delete | 4 | | NAT44 BIB create | 5 | | NAT44 BIB delete | 6 | | NAT64 BIB create | 7 | | NAT64 BIB delete | 8 | | NAT Addresses exhausted | 9 | | NAT ports exhausted | 10 | | Quota exceeded | 11 | | PCP MAP Create | 12 | | PCP MAP Delete | 13 | | PCP PEER Create | 14 | | PCP PEER Delete | 15 | +-------------------------+--------+ Table 2: NAT Event ID table 4.3. Templates for NAT Events The following events are identified at the time of this writing but the events are expandable. Depending on the implementation and configuration various IE's specified can be included or ignored 4.3.1. NAT44 create and delete session event This event will be generated when a NAT44 session is created or deleted. The template will be the same, the natEvent will indicate whether it is a create or a delete event. The following is a template of the event. Sivakumar & Penno Expires April 26, 2012 [Page 6] Internet-Draft Logging of NAT Events October 2011 +----------------------------------+-------------+-----------+ | Field Name | Size (bits) | Mandatory | +----------------------------------+-------------+-----------+ | timeStamp | 64 | Yes | | vlanId | 16 | No | | ingressVRFID | 32 | No | | sourceIPv4Address | 32 | Yes | | postNATSourceIPv4Address | 32 | Yes | | protocolIdentifier | 8 | Yes | | sourceTransportPort | 16 | Yes | | postNAPTsourceTransportPort | 16 | Yes | | destinationIPv4Address | 32 | No | | postNATDestinationIPv4Address | 32 | No | | destinationTransportPort | 16 | No | | postNAPTdestinationTransportPort | 16 | No | | natOriginatingAddressRealm | 8 | No | | natEvent | 8 | Yes | +----------------------------------+-------------+-----------+ Table 3: NAT44 Session delete/create template 4.3.2. NAT64 create and delete session event This event will be generated when a NAT64 session is created. The following is a template of the event. +----------------------------------+-------------+-----------+ | Field Name | Size (bits) | Mandatory | +----------------------------------+-------------+-----------+ | timeStamp | 64 | Yes | | sourceIPv6Address | 128 | Yes | | postNATSourceIPv4Address | 32 | Yes | | protocolIdentifier | 8 | Yes | | sourceTransportPort | 16 | Yes | | postNAPTsourceTransportPort | 16 | Yes | | destinationIPv6Address | 128 | No | | postNATDestinationIPv4Address | 32 | No | | destinationTransportPort | 16 | No | | postNAPTdestinationTransportPort | 16 | No | | natOriginatingAddressRealm | 8 | No | | natEvent | 8 | Yes | +----------------------------------+-------------+-----------+ Table 4: NAT64 session create/delete event template Sivakumar & Penno Expires April 26, 2012 [Page 7] Internet-Draft Logging of NAT Events October 2011 4.3.3. NAT44 BIB create and delete event This event will be generated when a NAT44 Bind entry is created. The following is a template of the event. +-----------------------------+-------------+-----------+ | Field Name | Size (bits) | Mandatory | +-----------------------------+-------------+-----------+ | timeStamp | 64 | Yes | | vlanId | 16 | No | | ingressVRFID | 32 | No | | sourceIPv4Address | 32 | Yes | | postNATSourceIPv4Address | 32 | Yes | | protocolIdentifier | 8 | No | | sourceTransportPort | 16 | No | | postNAPTsourceTransportPort | 16 | No | | natOriginatingAddressRealm | 8 | No | | natEvent | 8 | Yes | +-----------------------------+-------------+-----------+ Table 5: NAT44 BIB create/delete event template 4.3.4. NAT64 BIB create and delete event This event will be generated when a NAT64 Bind entry is created. The following is a template of the event. +-----------------------------+-------------+-----------+ | Field Name | Size (bits) | Mandatory | +-----------------------------+-------------+-----------+ | timeStamp | 64 | Yes | | sourceIPv6Address | 128 | Yes | | postNATSourceIPv4Address | 32 | Yes | | protocolIdentifier | 8 | No | | sourceTransportPort | 16 | No | | postNAPTsourceTransportPort | 16 | No | | natOriginatingAddressRealm | 8 | No | | natEvent | 8 | Yes | +-----------------------------+-------------+-----------+ Table 6: NAT64 BIB create/delete event template 4.3.5. DS-Lite Session Create and Delete Event This is the generic template to log DS-Lite session events. If the purpose of the logging event is to identify a subscriber for traceability purposes, the following fields can be ommitted: sourceIPv4Address, protocolIdentifier, sourceIPv4TransportPort, Sivakumar & Penno Expires April 26, 2012 [Page 8] Internet-Draft Logging of NAT Events October 2011 destinationIPv6Address, destinationIPv4TransportPort, natOriginatingAddressRealm +----------------------------------+-------------+-----------+ | Field Name | Size (bits) | Mandatory | +----------------------------------+-------------+-----------+ | timeStamp | 64 | Yes | | sourceIPv6Address | 128 | Yes | | sourceIPv4Address | 32 | Yes | | postNATSourceIPv4Address | 32 | Yes | | protocolIdentifier | 8 | Yes | | sourceIPv4TransportPort | 16 | Yes | | postNAPTsourceTransportPort | 16 | Yes | | destinationIPv6Address | 128 | Yes | | postNATDestinationIPv4Address | 32 | Yes | | destinationIPv4TransportPort | 16 | Yes | | postNAPTdestinationTransportPort | 16 | Yes | | natOriginatingAddressRealm | 8 | No | | natEvent | 8 | Yes | +----------------------------------+-------------+-----------+ Table 7: DS-Lite session create/delete event template 4.3.6. DS-Lite BIB Create and Delete Event This event will be generated when a DS-Lite BIB is created or deleted. +-----------------------------+-------------+-----------+ | Field Name | Size (bits) | Mandatory | +-----------------------------+-------------+-----------+ | timeStamp | 64 | Yes | | sourceIPv6Address | 128 | Yes | | sourceIPv4Address | 32 | Yes | | postNATSourceIPv4Address | 32 | Yes | | protocolIdentifier | 8 | Yes | | sourceIPv4TransportPort | 16 | Yes | | postNAPTsourceTransportPort | 16 | Yes | | destinationIPv6Address | 128 | Yes | | natOriginatingAddressRealm | 8 | No | | natEvent | 8 | Yes | +-----------------------------+-------------+-----------+ Table 8: DS-Lite bib create/delete event template Sivakumar & Penno Expires April 26, 2012 [Page 9] Internet-Draft Logging of NAT Events October 2011 4.3.7. PCP MAP Create and Delete Event This event is generated when a PCP Server creates or deletes a PCP NAT mapping. +----------------------------+-------------+-----------+ | Field Name | Size (bits) | Mandatory | +----------------------------+-------------+-----------+ | timeStamp | 64 | Yes | | vlanId | 16 | No | | ingressVRFID | 32 | No | | PCPClientAdress | 128 | Yes | | ExternalIPAdress | 128 | Yes | | InternalIPAddress | 128 | Yes | | protocolIdentifier | 8 | No | | ExternalPort | 16 | Yes | | InternalPort | 16 | Yes | | natOriginatingAddressRealm | 8 | No | | natEvent | 8 | Yes | +----------------------------+-------------+-----------+ Table 9: PCP MAP4 create and delete event template 4.3.8. PCP PEER Create and Delete Event This event is generated when a PCP Server creates or deletes a PCP PEER mapping. +----------------------------+-------------+-----------+ | Field Name | Size (bits) | Mandatory | +----------------------------+-------------+-----------+ | timeStamp | 64 | Yes | | vlanId | 16 | No | | ingressVRFID | 32 | No | | PCPClientAdress | 128 | Yes | | RemoteIPPAdress | 128 | Yes | | ExternalIPAddress | 128 | Yes | | protocolIdentifier | 8 | Yes | | InternallPort | 16 | Yes | | ExternalPort | 16 | Yes | | RemotePort | 16 | Yes | | natOriginatingAddressRealm | 8 | No | | natEvent | 8 | Yes | +----------------------------+-------------+-----------+ Table 10: PCP PEER4 create and delete event template Sivakumar & Penno Expires April 26, 2012 [Page 10] Internet-Draft Logging of NAT Events October 2011 4.3.9. Addresses Exhausted event This event will be generated when a NAT device runs out of global IPv4 addresses. Typically, this event would mean that the NAT device wont be able to create any new translations until some addresses/ ports are freed. The following is a template of the event. +--------------------------+-------------+-----------+ | Field Name | Size (bits) | Mandatory | +--------------------------+-------------+-----------+ | timeStamp | 64 | Yes | | natEvent | 8 | Yes | | postNATSourceIPv4Address | 32 | Yes | +--------------------------+-------------+-----------+ Table 11: NAT Address Exhausted event template 4.3.10. Ports Exhausted event This event will be generated when a NAT device runs out of ports for a global IPv4 address. Port exhaustion shall be reported per protocol (UDP, TCP etc) The following is a template of the event. +--------------------------+-------------+-----------+ | Field Name | Size (bits) | Mandatory | +--------------------------+-------------+-----------+ | timeStamp | 64 | Yes | | natEvent | 8 | Yes | | postNATSourceIPv4Address | 32 | Yes | | protocolIdentifier | 8 | Yes | +--------------------------+-------------+-----------+ Table 12: NAT Ports Exhausted event template 4.3.11. Quota exceeded This event will be generated when a NAT device cannot allocate resources as a result of an administratively defined policy. The examples of Quota exceeded are to allow only certain number of NAT sessions per device, certain number of NAT sessions per user etc. The following is a template of the event. Sivakumar & Penno Expires April 26, 2012 [Page 11] Internet-Draft Logging of NAT Events October 2011 +--------------------+-------------+-----------+ | Field Name | Size (bits) | Mandatory | +--------------------+-------------+-----------+ | timeStamp | 64 | Yes | | natEvent | 8 | Yes | | Limit value | 32 | Yes | | sourceIPv4 address | 32 | No | | sourceIPv6 address | 128 | No | +--------------------+-------------+-----------+ Table 13: NAT Quota Exceeded event template 5. Acknowledgements Thanks to Dan Wing, Selvi Shanmugam, Mohamed Boucadir, Jacni Qin and Ramji Vaithianathan for their review and comments. 6. IANA Considerations IANA is requested to create a new registry, titled NAT Event Logging [NAT-EVENT-LOG-IANA]. This new registry is initially populated with the values from Section 4.2. Additional values can be created via Specification Required [RFC5226]. 7. Security Considerations None. 8. References 8.1. Normative References [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. [RFC4787] Audet, F. and C. Jennings, "Network Address Translation (NAT) Behavioral Requirements for Unicast UDP", BCP 127, RFC 4787, January 2007. [RFC5382] Guha, S., Biswas, K., Ford, B., Sivakumar, S., and P. Sivakumar & Penno Expires April 26, 2012 [Page 12] Internet-Draft Logging of NAT Events October 2011 Srisuresh, "NAT Behavioral Requirements for TCP", BCP 142, RFC 5382, October 2008. [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. 8.2. Informative References [I-D.ietf-pcp-base] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P. Selkirk, "Port Control Protocol (PCP)", draft-ietf-pcp-base-16 (work in progress), October 2011. [I-D.ietf-softwire-dual-stack-lite] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- Stack Lite Broadband Deployments Following IPv4 Exhaustion", draft-ietf-softwire-dual-stack-lite-11 (work in progress), May 2011. [NAT-EVENT-LOG-IANA] IANA, "NAT event log entities", 2011, . Authors' Addresses Senthil Sivakumar Cisco Systems 7100-8 Kit Creek Road Research Triangle Park, North Carolina 27709 USA Phone: +1 919 392 5158 Email: ssenthil@cisco.com Renaldo Penno Juniper Networks 1194 N Mathilda Avenuw Sunnyvale, California 94089 USA Phone: Email: rpenno@juniper.net Sivakumar & Penno Expires April 26, 2012 [Page 13]