IP Security Maintenance and Extensions A. Yamaya, Ed. (ipsecme) K. Ueki Internet-Draft T. Murai Intended status: Informational Furukawa Network Solution Corp. Expires: August 18, 2013 February 18, 2013 simple VPN solution using Multi-point Security Association draft-yamaya-ipsecme-mpsa-00.txt Abstract This document describes the over-lay network solution by utilizing dynamically established IPsec multi-point Security Association (SA) without individual connection. Multi-point SA technology provides the simplified mechanism of the Auto Discovery and Configuration function. This is applicable for any IPsec tunnels such as IPv4 over IPv4, IPv4 over IPv6, IPv6 over IPv4 and IPv6 over IPv6. 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 August 18, 2013. Copyright Notice Copyright (c) 2013 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 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 . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3. Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 3.1. Sequence . . . . . . . . . . . . . . . . . . . . . . . . . 3.2. Extended Format . . . . . . . . . . . . . . . . . . . . . 3.2.1 Vendor ID . . . . . . . . . . . . . . . . . . . . . . . . 3.2.2 MPSA_PUT . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Multi-point SA Management . . . . . . . . . . . . . . . . 3.3.1 Gateway . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.2 Endpoint . . . . . . . . . . . . . . . . . . . . . . . . . 3.3.3 Rekeying . . . . . . . . . . . . . . . . . . . . . . . . 3.4. Forwarding . . . . . . . . . . . . . . . . . . . . . . . . 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7. Normative References. . . . . . . . . . . . . . . . . . . . . Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 1. Introduction As described in the problem statement document[ad-vpn-problem], dynamic, secure and scalable system for establishing SAs is needed. With multi-point SA, an endpoint automatically discovers other endpoints. The endpoints also share a multi-point SA within the same group, and there is no individual connection between them. It can avoid the exhaustive configuration for endpoints/ gateways. No reconfiguration is needed when a new endpoint is added, removed, or changed. It can avoid high load on the gateways. 1.1. Terminology Multi-point SA - This is similar to Dynamic Full Mesh topology described in [ad-vpn-problem]; direct connections exist in a hub and spoke manner, but only one SA for data transfer is shared with all endpoints. 2. Motivation There are two major topologies - Star topology and full-mesh topology - to communicate securely on over-lay network by using IPsec. Figure.1 shows star topology. The number of IPsec connection is the same as the number of endpoints (EP). Authentication, Authorization and Accounting (AAA) of each endpoint can be achieved on the gateway. The problem of the star topology is all the traffic go through the gateway, then it causes high load and latency. +---------------------------------------------+ | IPsec Gateway | | | | +--------------(A<->C)--------------+ | | | +---(A<->B)---+ +---(B<->C)---+ | | +---:|-|:-----------:|---|:-----------:|-|:---+ :| |: :| |: :| |: :| |: :| |: :| |: :| |: :| |: :| |: +---:v-v:---+ :| |: +---:v-v:---+ | | :| |: | | | EP_A | :| |: | EP_C | | | :| |: | | +-----------+ :| |: +-----------+ +--:v---v:--+ | | | EP_B | | | +-----------+ Figure 1 Figure.2 shows Full-mesh topology. There is no gateways. Each endpoint establishes IPsec connection independently. The latency on this topology is relatively low compared to star topology. In large system, there are huge number ((N^2-N)/2) of IPsec connections. AAA of each endpoint is hard to manage in this topology. Moreover, when a endpoint is added, removed or changed, reconfiguration is needed for all rest of the endpoints. +-----------+ +-----------+ | |.....................| | | EP_A <-------(A<->C)-------> EP_C | | |.....................| | +---: ^ :---+ +---: ^ :---+ : | : : | : : | : +-----------+ : | : : | :........| |........: | : : +-(A<->B)--> EP_B <--(B<->C)-+ : :............| |............: +-----------+ Figure 2 The solution in this document eliminates the problems listed above. Figure 3 shows topology of multi-point SA. Traffic between endpoints does not go through the gateway, low latency, AAA of each endpoint can be achieved, the number of IPsec connection is almost same as star topology, and no reconfiguration is needed for all the rest of endpoints even when a endpoint is added, removed or changed. +---------------------------------------------+ | IPsec Gateway | | | +---: | :------------: | :------------: | :---+ : | : : | : : | : : | : : | : : | : ----------------------------------------- SA to distribute : | : : | : : | : Multi-point SA : | : : | : : | : +---: v :---+ +---: v :---+ +---: v :---+ | | | | | | | EP_A | | EP_B | | EP_C | | | | | | | +--- ^ ^ ---+ +--- ^ ^ ---+ +--- ^ ^ ---+ .....| |..............| |..............| |..... | | | | | | \ | +----(A<->B)---+ +---(B<->C)----+ | Multi-point SA +--------------(A<->C)--------------+ for data transfer .............................................../ Figure 3 3. Procedure 3.1 Sequence The multi-point SA capability of the remote host is determined by an exchange of Vendor ID payloads. In the IKE_SA_INIT exchange, the Vendor ID payload for this specification is sent if the multi-point SA is used. Endpoint Gateway ----------- ----------- HDR, SAi1, KEi, Ni, V(MPSA) --> <-- HDR, SAr1, KEr, Nr, V(MPSA), [CERTREQ] MPSA : multi-point SA The initial exchange (including IKE_AUTH) is same as [IKEV2], other than Vendor ID payload included in IKE_SA_INIT. After the initial exchange has finished successfully, a new INFORMATIONAL exchange is used to distribute multi-point SA to the endpoint, with the Notify payload of MPSA_PUT that includes cryptographic algorithm, nonce, keying material, SPI and so on. Keys for multi-point SA is generated according to the contents of the Notify payload bythe endpoint. The response of the Notify payload has empty Encrypted payload. Endpoint Gateway ----------- ----------- <-- HDR, SK {N(MPSA_PUT)} HDR, SK {} --> 3.2 Extended format 3.2.1 Vendor ID This document defines a new Vendor ID. The content of the payload is described below. "multi-point SA" 3.2.2 MPSA_PUT This document defines a new Notify Message Type MPSA_PUT. The Notify Message Type of MPSA_PUT is 40960. Notification Data of MPSA_PUT has a Proposal-substructure-like format. It consists of Transform-substructure-like structures that have following data. Description Trans. Reference Type ------------------------------------------------------------------ Encryption Algorithm (ENCR) 1 RFC5996 Pseudorandom Function (PRF) 2 RFC5996 Integrity Algorithm (INTEG) 3 RFC5996 Nonce (NONCE) 241 SK_d (SKD) 242 Lifetime (LIFE) 243 Rollover time 1 (ROLL1) 244 Rollover time 2 (ROLL2) 245 - Nonce For Nonce, the Transform ID is 1. The attribute contains actual nonce value with attribute type 16384. The size of the Nonce Data is between 16 and 256 octets. Name Number --------------------------------------------------- NONCE_NONCE 1 Attribute Type Value Attribute Format ------------------------------------------------------------ Nonce Value 16384 TLV - SK_d For SK_d, the Transform ID is 1. The attribute contains actual SK_d value with attribute type 16385. The length of SK_d Data is the preferred key length of the PRF. Name Number --------------------------------------------------- SKD_SK_D 1 Attribute Type Value Attribute Format ------------------------------------------------------------ SK_d Value 16385 TLV - Lifetime For Lifetime, the Transform ID is 1. The attribute contains actual lifetime value with attribute type 16386. The length of Lifetime Value is 4 octets. Lifetime is stored in seconds as effective time of the multi-point SA. Name Number --------------------------------------------------- LIFE_LIFETIME 1 Attribute Type Value Attribute Format ------------------------------------------------------------ Lifetime Value 16386 TLV - Rollover time 1 For Rollover time 1, the Transform ID is 1. The attribute contains actual rollover time 1 value with attribute type 16387. The length of Rollover time 1 Value is 4 octets. Rollover time 1 defines activation time delay for new outbound multi-point SA. Name Number --------------------------------------------------- ROLL1_ROLLOVER1 1 Attribute Type Value Attribute Format ------------------------------------------------------------ Rollover1 Value 16387 TLV - Rollover time 2 For Rollover time 2, the Transform ID is 1. The attribute contains actual rollover time 2 value with attribute type 16388. The length of Rollover time 2 Value is 4 octets. Rollover time 2 defines deactivation time delay for old inbound multi-point SA. Name Number --------------------------------------------------- ROLL2_ROLLOVER2 1 Attribute Type Value Attribute Format ------------------------------------------------------------ Rollover2 Value 16388 TLV Therefore, the format of the MPSA_PUT of the Notify Message is described below. 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Next Payload |C| RESERVED | Payload Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Protocol ID | SPI Size | Notify Message Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Security Parameter Index (SPI) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 0 (last) or 2 | RESERVED | Proposal Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Proposal Num | Protocol ID | SPI Size |Num Transforms| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Security Parameter Index (SPI) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 0 (last) or 3 | RESERVED | Transform Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Transform Type | RESERVED | Transform ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Transform Attributes ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 0 (last) or 3 | RESERVED | Transform Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Transform Type | RESERVED | Transform ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Transform Attributes ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 0 | RESERVED | Transform Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |Transform Type | RESERVED | Transform ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | ~ Transform Attributes ~ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The following example shows a N(MPSA_PUT) notification message. The SPIs in the Proposal-like and Tranform-like substructure are the same value. Following values are defined by the example. Protocol: ESP ENCR: AES-CBC (256bits) PRF: SHA-1 INTEG: HAMC-SHA-1-96 NONCE: 241 SKD: 242 LIFE: 243 ROLL1: 244 ROLL2: 245 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\ | 0 (last) |C| RESERVED | Payload Length | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ | 3 (ESP) | SPI Size = 4 | MPSA_PUT | Notify +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / | Security Parameter Index (SPI) | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+< | 0 (last) | RESERVED | Proposal Length | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Proposal- | Prop Num = 1 | 3 (ESP) | SPI Size = 4 |Num Transforms| like +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / | Security Parameter Index (SPI) | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+< | 3 | RESERVED | Transform Length | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ | 1 (ENCR) | RESERVED | 12 (ENCR_AES_CBC) | ENCR +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / |1| 14 (Key Length) | 256 | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+< | 3 | RESERVED | Transform Length | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ PRF | 2 (PRF) | RESERVED | 2 (PRF_HMAC_SHA1) | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+< | 3 | RESERVED | Transform Length | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ INTEG | 3 (INTEG) | RESERVED | 2 (AUTH_HMAC_SHA1_96) | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+< | 3 | RESERVED | Transform Length | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ | 241 (NONCE) | RESERVED | 1 | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ |0| 16384 (Nonce) | Attribute Length | NONCE +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / | | / ~ [Nonce] ~ / | | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+< | 3 | RESERVED | Transform Length | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ | 242 (SKD) | RESERVED | 1 | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ |0| 16385 (SK_d) | Attribute Length | SKD +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / | | / ~ [SK_d] ~ / | | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+< | 3 | RESERVED | Transform Length | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ | 243 (LIFE) | RESERVED | 1 | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ LIFE |0| 16386 (Lifetime) | Attribute Length = 4 | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / | [Lifetime] | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+< | 3 | RESERVED | Transform Length | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ | 244 (ROLL1) | RESERVED | 1 | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ROLL1 |0| 16386 (Lifetime) | Attribute Length = 4 | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / | [RolloverTime1] | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+< | 3 | RESERVED | Transform Length | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ \ | 245 (ROLL2) | RESERVED | 1 | \ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ROLL2 |0| 16386 (Lifetime) | Attribute Length = 4 | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / | [RolloverTime2] | / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+< 3.3 Multi-point SA Management 3.3.1 Gateway Gateway generates a multi-point SA for a group before connecting to any endpoints. After the initial exchanges have finished, Gateway distributes the same multi-point SA information to endpoints within the group by sending N(MPSA_PUT). SPI and Nonce is generated similar way of [IKEv2]. SK_d is generated from random numbers similar to Nonce. The same SPI value is stored to Notify payload and Proposal-like substructure. The multi-point SA will not be negotiated between gateway and endpoint, but will be notified from gateway to endpoint one way. Gateway initiates rekey before Lifetime expiration. As the Lifetime, gateway notifies the effective time left of the multi-point SA. 3.3.2 Endpoint After the initial exchange has finished, Endpoint obtains multi-point SA information by receiving N(MPSA_PUT) from gateway. The keys for the multi-point SA are generated in the same procedure described in [IKEv2], except Ni | Nr is replaced by Nonce. Therefore, KEYMAT is derived by PRF listed below. KEYMAT = prf+(SK_d, Nonce) The multi-point SA is protected in a cryptographic manner by ENCR and INTEG which uses the generated keys. The SPI value for the multi-point SA is the same of its in Notify message. Endpoint uses the same multi-point SA as both inbound and outbound SAs. Endpoint deletes both of inbound and outbound SA when Lifetime is expired. Rollover time 1, 2 have no meaning when no old multi-point SA exists. 3.3.3 Rekeying Rekeying should be finished before Lifetime expiration of current multi-point SA. Rekeying of multi-point SA will be performed as follows. - Gateway generates a new multi-point SA - Gateway distributes a new multi-point SA to all endpoints within the group - Endpoint replaces the current multi-point SA to new one Endpoint replaces multi-point SA using rollover method like [GDOI]. 3.4 Forwarding Each endpoint sends and receives encapsulated packets using the multi-point SA. The destination address of encapsulated packet will be determined with routing information, which can achieved by static configuration or route exchange mechanism such as BGP on encapsulated environment described in [MESH]. It is applicable for any IPsec tunnels such as IPv4 over IPv4, IPv4 over IPv6, IPv6 over IPv4 and IPv6 over IPv6. 4. Security Considerations 5. IANA Considerations There is no new IANA considerations in this document. 6. References 6.1 Normative References [IKEv2] Charlie Kaufman, Paul Hoffman, Yoav Nir, Pasi Eronen "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC5596, September 2010 6.2 Informative References [GDOI] B. Weis, S. Rowles, T. Hardjono "The Group Domain of Interpretation" RFC6407, October 2011 [MESH] J. Wu, Y. Cui, C. Metz, E. Rosen "Softwire Mesh Framework" RFC5565, June 2009 [ad-vpn-problem] S. Hanna, V. Manral "Auto Discovery VPN Problem Statement and Requirements" draft-ietf-ipsecme-ad-vpn-problem-03, "work in progress." December 17, 2012 7. Acknowledgments Author's Addresses Arifumi Yamaya Furukawa Network Solution Corp. 5-1-9, Higashi-Yawata, Hiratsuka Kanagawa 254-0016, JAPAN Email: yamaya@fnsc.co.jp Ken Ueki Furukawa Network Solution Corp. 5-1-9, Higashi-Yawata, Hiratsuka Kanagawa 254-0016, JAPAN Email: ueki@fnsc.co.jp Tomoki Murai Furukawa Network Solution Corp. 5-1-9, Higashi-Yawata, Hiratsuka Kanagawa 254-0016, JAPAN Email: murai@fnsc.co.jp