Network Working Group P. Srisuresh
Request for Comments: 5508 Kazeon Systems
BCP: 148 B. Ford
Category: Best Current Practice MPI-SWS
S. Sivakumar
Cisco Systems
S. Guha
Cornell U.
April 2009
NAT Behavioral Requirements for ICMP
Status of This Memo
This document specifies an Internet Best Current Practices for the
Internet Community, and requests discussion and suggestions for
improvements. Distribution of this memo is unlimited.
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Srisuresh, et al. Best Current Practice [Page 1]
RFC 5508 NAT Behavioral Requirements for ICMP April 2009
Abstract
This document specifies the behavioral properties required of the
Network Address Translator (NAT) devices in conjunction with the
Internet Control Message Protocol (ICMP). The objective of this memo
is to make NAT devices more predictable and compatible with diverse
application protocols that traverse the devices. Companion documents
provide behavioral recommendations specific to TCP, UDP, and other
protocols.
Table of Contents
1. Introduction and Scope ..........................................3
2. Terminology .....................................................4
3. ICMP Query Handling .............................................6
3.1. ICMP Query Mapping .........................................6
3.2. ICMP Query Session Timeouts ................................7
4. ICMP Error Forwarding ...........................................8
4.1. ICMP Error Payload Validation ..............................8
4.2. ICMP Error Packet Translation .............................10
4.2.1. ICMP Error Packet Received from the External Realm .11
4.2.2. ICMP Error Packet Received from the Private Realm ..13
4.3. NAT Sessions Pertaining to ICMP Error Payload .............15
5. Hairpinning Support for ICMP Packets ...........................16
6. Rejection of Outbound Flows Disallowed by NAT ..................17
7. Conformance to RFC 1812 ........................................17
7.1. IP Packet Fragmentation ...................................19
7.1.1. Generating "Packet Too Big" ICMP Error Message ....19
7.1.2. Forwarding "Packet Too Big" ICMP Error Message ....20
7.2. Time Exceeded Message .....................................20
7.3. Source Route Options ......................................20
7.4. Address Mask Request/Reply Messages .......................20
7.5. Parameter Problem Message .................................21
7.6. Router Advertisement and Solicitations ....................21
7.7. DS Field Usage ............................................21
8. Non-QueryError ICMP Messages ...................................22
9. Summary of Requirements ........................................22
10. Security Considerations .......................................25
11. Acknowledgements ..............................................26
12. References ....................................................27
12.1. Normative References .....................................27
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