Network Working Group Louis Chan INTERNET-DRAFT Intended status: Standard Track Juniper Networks Expires: Aug 21, 2022 Feb 21, 2022 Enhanced Port Forwarding functions with CGNAT draft-chan-tsvwg-eipf-cgnat-00.txt Abstract There is a need for peer-to-peer (P2P) communication under the use of CGNAT in service providers. With the combination of home gateway, this becomes NAT444. In RFC5128, methods of using UDP hole punching solves the problem partially when EIM (Endpoint-Independent Mapping) is supported in NAT device in the path, and there exists a common rendezvous server. The success rate of UDP hole punching is high, but not TCP hole punching in practical world. Also, the P2P solution requires a common server in the public internet to exchange the IP and port information. In this draft, a method is described to achieve incoming TCP or UDP session without a common rendezvous server in NAT444 situation. 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 Aug 21, 2022. Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. Chan Expires Aug 21, 2022 [Page 1] Internet-Draft draft-chan-tsvwg-eipf-cgnat-00 February 2022 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 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. Introduction ......................................................... 2 2. Conventions used in this document..................................... 3 3. Port acquiring procedure in Application............................... 3 4. Endpoint Independent port forwarding (EIPF) Enhancement .............. 4 4.1. When this feature enabled in CGNAT with EIM...................... 4 4.2. When this feature is enabled in CGNAT with both EIM and EIF ..... 4 5. Retrieval of IP and port information via HTTP......................... 5 5.1. IP and port - URI /ipport/ ...................................... 5 5.2. IP and port range - URI /ipportrange/............................ 5 6. Compatibility ........................................................ 6 7. Security Considerations .............................................. 6 8. References ........................................................... 6 8.1. Normative References ............................................ 6 8.2. Informative References .......................................... 6 9. Acknowledgments....................................................... 7 1. Introduction The purpose of this document is to describe to a way to allow incoming TCP or UDP sessions under NAT444 situation. The success rate of TCP and UDP session would be guaranteed under this proposal. There would be two sections in the draft. - The first section describes a procedure for an application in end device to detect and allocate TCP or UDP port for its use for incoming session. The required tools are STUN [RFC5389] and UPNP [RFC6970]. - The second section describes a method for residential gateway RG to discover the usable port range under a CGNAT deployment with port-block-allocation. In turn, the home gateway could allocate TCP or UDP to the end devices via UPNP, NAT-PMP [RFC6886] or PCP [RFC6887]. Chan Expires Aug 21, 2022 [Page 2] Internet-Draft draft-chan-tsvwg-eipf-cgnat-00 February 2022 2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. In this document, these words will appear with that interpretation only when in ALL CAPS. Lower case uses of these words are not to be interpreted as carrying significance described in RFC 2119. 3. Port acquiring procedure in Application PC1-----RG-------CGNAT------Internet------PC2 | +-----STUN server - Private network: PC1: 192.168.1.10, RG: 192.168.1.1 - WAN: RG: 10.1.1.20, CGNAT: 10.1.1.1 - CGNAT: public IP 100.1.1.1 - PC2: public IP 201.1.1.10 Here is an example of step to acquire a TCP or UDP port - Application in PC1 sends a STUN request to STUN servers in public internet. The STUN server would reply the XOR-mapped-address. E.g. 100.1.1.1:1024 ;public ip is 100.1.1.1 with port 1024 This detects both public IP address and the UDP port available. This assumes the same TCP port is also available since most CGNAT implementations allocate the same port number for both TCP and UDP with EIM enabled. The application will then send UPNP request to residential gateway RG, 192.168.1.1, for port forward TCP port 1024 to the local device IP, 192.168.1.10. - CGNAT, due to PBA allocation and a special setting enabled, TCP traffic sent to 100.1.1.1:1024 as destination would be forwarded to RG 10.1.1.20:1024 without changing port value. Then, RG would pass the TCP traffic to PC1 with 192.168.10.1:1024 as destination due to the registration of UPNP. In this case, PC2 could initiate a direct TCP session to PC1 via 100.1.1.1:1024. - UDP would work in the same way. Any host in the internet could create TCP or UDP session directly with the application in PC1 The above procedure assumes both RG and CGNAT have EIM capability enabled. Chan Expires Aug 21, 2022 [Page 3] Internet-Draft draft-chan-tsvwg-eipf-cgnat-00 February 2022 The application in PC1, optionally, could release the UPNP mapping after finishing the session. 4. Endpoint Independent Port Forwarding (EIPF) Enhancement 4.1. When this feature enabled in CGNAT with EIM - the associated TCP or UDP port is UNCHANGED for the inbound traffic if there is no matching session in the NAT table. - only the IP address is going through NAT process. That is changing the public IP to a private IP - It is working like port forward function in a NAT44 - In the example, any IP source address, 202.1.1.1 or 222.1.1.1, sending traffic to 100.1.1.1:1024. CGNAT would translate the traffic as 10.1.1.20:1024 as destination. - UDP hole punching would be compatible if the UDP session is still in RG and CGNAT session table. Port 1024 would follow the translation. 4.2. When this feature is enabled in CGNAT with both EIM and EIF - EIF (Endpoint-Independent Filtering), described in RFC5128, will happen only if the external host already has a session through EIM. - The TCP or UDP port is kept UNCHANGED for any other external hosts sending inbound traffic. - For example, there is a session originated from PC1 to PC3, 201.1.1.20 PC1-----------RG----------CGNAT-----------Internet---------PC3 | +---------------------PC4 Src: 192.168.1.10:3333 10.1.1.20:4444 100.1.1.1:1033 Dst: 201.1.1.20:5555 201.1.1.20:5555 201.1.1.20:5555 When PC3 sends traffic with different source port, 201.1.1.20:6666 and destination 100.1.1.1:1033, CGNAT should honor the EIF behavior. It would be translated back to 10.1.1.20:4444. When other host without any session established through EIM, and it sends traffic with destination port 1033, the port 1033 should not be changed at CGNAT. When PC4 send traffic to 100.1.1.1:1033, the port 1033 is kept UNCHANGED. PC4 has no previous established sessions with PC1. This behavior is an optional implementation with EIF enabled. Another option is to make EIPF and EIF exclusive. Chan Expires Aug 21, 2022 [Page 4] Internet-Draft draft-chan-tsvwg-eipf-cgnat-00 February 2022 5. Retrieval of IP and port information via HTTP The internet service provider host a HTTP web server for the enquiry of IP and port information. Two URIs are suggested 5.1. IP and port - URI /ipport/ With the URI /ipport/, the HTTP response is clear text with IP:PORT, where IP is the external public IP address and the PORT is external port as seen. For example, the response is 100.1.1.1:1040 The HTTP response should be human readable with a web browser. Although TCP port 1040 is seen here, it is assumed that UDP port 1040 is also available from CGNAT for incoming mapping. 5.2. IP and port range - URI /ipportrange/ With the URI /ipportrange/, the HTTP response is clear text with IP:PORT_START:PORT_END IP:PORT_START:PORT_END IP:PORT_START Where is ASCII character for line feed. The response is a human readable format in a normal web browser. For examples, here are valid responses a) Single line 100.1.1.1:1024:1031 Port range 1024 to 1031 assigned for both TCP and UDP. b) Two lines 100.1.1.1:1024:1031 100.1.1.1:1064:1071 Port ranges 1024 to 1031 and range 1064 and 1071 are assigned for both TCP and UDP. It is possible to have multiple port block allocated to the same private IP address from CGNAT perspective. Chan Expires Aug 21, 2022 [Page 5] Internet-Draft draft-chan-tsvwg-eipf-cgnat-00 February 2022 If the RG device or application could not support multiple entries of IP and port range, it should take one of the lines, preferably the first line. Human user or RG could use this information to plan for incoming services. For example, when PC1 requests a TCP 8888 port forward from RG via UPNP [RFC6970], NAT- PMP [RFC6886] or PCP [RFC6887], RG would counter offer another TCP port 1031. 6. Compatibility TBD 7. Security Considerations TBD 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. 8.2. Informative References [RFC5128] Srisuresh, P., Ford, B., and D. Kegel, "State of Peer-to- Peer (P2P) Communication across Network Address Translators (NATs)", March 2008. [RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing, "Session Traversal Utilities for NAT (STUN)", October 2008. [RFC6886] S. Cheshire and M. Krochmal. NAT Port Mapping Protocol (NAT-PMP), April 2013. [RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P. Selkirk, "Port Control Protocol (PCP)", April 2013. [RFC6970] Boucadair, M., Penno, R., and D. Wing, "Universal Plug and Play (UPnP) Internet Gateway Device - Port Control Protocol Interworking Function (IGD-PCP IWF)", July 2013 Chan Expires Aug 21, 2022 [Page 6] Internet-Draft draft-chan-tsvwg-eipf-cgnat-00 February 2022 9. Acknowledgments The following people have contributed to this document: Author Address Louis Chan (editor) Juniper Networks 2604, Cityplaza One, 1111 King's Road Taikoo Shing Hong Kong Phone: +852-25876659 Email: louisc@juniper.net Chan Expires Aug 21, 2022 [Page 7]