IPSEC Working Group Baiju Patel INTERNET-DRAFT Intel Category: Standards Track Bernard Aboba <draft-ietf-ipsec-dhcp-10.txt> Microsoft Scott Kelly RedCreek Communications Vipul Gupta Sun Microsystems, Inc. DHCPv4 Configuration of IPSEC Tunnel Mode This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. This document is an Internet-Draft. Internet-Drafts are working docu- ments of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Copyright Notice Copyright (C) The Internet Society (2001). All Rights Reserved. Abstract In many remote access scenarios, a mechanism for making the remote host appear to be present on the local corporate network is quite useful. This may be accomplished by assigning the host a "virtual" address from the corporate network, and then tunneling traffic via Ipsec from the host's ISP-assigned address to the corporate security gateway. In IPv4, Dynamic Host Configuration Protocol (DHCP) provides for such remote host configuration. This draft explores the requirements for host configuration in IPSEC tunnel mode, and describes how DHCPv4 may be leveraged for configuration. Patel, Aboba, Kelly & Gupta Standards Track [Page 1]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 1. Introduction In many remote access scenarios, a mechanism for making the remote host appear to be present on the local corporate network is quite useful. This may be accomplished by assigning the host a "virtual" address from the corporate network, and then tunneling traffic via IPSEC from the host's ISP-assigned address to the corporate security gateway. In IPv4, Dynamic Host Configuration Protocol (DHCP) [3] provides for such remote host configuration. This draft explores the requirements for host configuration in IPSEC tunnel mode, and describes how DHCPv4 may be leveraged for configuration. 1.1. Terminology This document uses the following terms: DHCP client A DHCP client or "client" is an Internet host using DHCP to obtain configuration parameters such as a network address. DHCP server A DHCP server or "server" is an Internet host that returns configuration parameters to DHCP clients. 1.2. Requirements language In this document, the key words "MAY", "MUST, "MUST NOT", "optional", "recommended", "SHOULD", and "SHOULD NOT", are to be interpreted as described in [1]. 2. IPSEC tunnel mode configuration requirements As described in [21], the configuration requirements of a host with an IPSEC tunnel mode interface include the need to obtain an IPv4 address and other configuration parameters appropriate to the class of host. In addition to meeting the basic requirements [21], the following additional capabilities may be desirable: 1. integration with existing IPv4 address management facilities 2. support for address pool management 3. reconfiguration when required 4. support for fail-over 5. maintaining security and simplicity in the IKE implementation. 6. authentication where required Patel, Aboba, Kelly & Gupta Standards Track [Page 2]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 2.1. DHCP configuration evaluation Leveraging DHCP for configuration of IPSEC tunnel mode meets the basic requirements described in [21]. It also provides the additional capabilities described above. Basic configuration In IPv4, leveraging DHCPv4 [3] for the configuration of IPSEC tunnel mode satisfies the basic requirements described in [21]. Since the required configuration parameters described in [21] are a subset of those already supported in DHCPv4 options [5], no new DHCPv4 options are required, and no modifications to DHCPv4 [3] are required. Address management integration Since DHCPv4 is widely deployed for address management today, reuse of DHCPv4 for IPSEC tunnel mode address management enables compatibility and integration with existing addressing implementations and IPv4 address management software. Address pool management As described in [18], DHCPv4 implementations support conditional behavior so that the address and configuration parameters assigned can be dependent on parameters included in the DHCPDISCOVER. This makes it possible for the security gateway to ensure that the client receives an IP address assignment from the appropriate address pool, such as via the User Class option, described in [16]. Reconfiguration DHCP supports the concept of configuration leases, and there is a proposal for handling forced reconfiguration [14]. Fail-over support When leveraging DHCPv4, configuration and addressing state is kept on the DHCP server, not within the IKE implementation. As a result, the loss of a tunnel server does not result in the loss of configuration and addressing state, thus making it easier to support fail-over [8]. Security and simplicity Leveraging DHCPv4 also makes it easier to maintain security in the IKE implementation since no IKE modifications are required to support configuration. Authentication Where DHCPv4 authentication [6] is required, this can be supported on an IPSEC tunnel mode interface as it would be on Patel, Aboba, Kelly & Gupta Standards Track [Page 3]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 any other interface. 2.2. Summary As described, DHCPv4 [3] meets the IPSEC tunnel mode configuration requirements [21], as well as providing additional capabilities. As described in the Appendix, IKECFG [13] does not meet the basic requirements, nor does it provide the additional capabilities. As a result, DHCPv4 is the superior alternative for IPSEC tunnel mode configuration. 3. Scenario overview IPSEC [2], [9]-[12] is a protocol suite defined to secure communication at the network layer between communicating peers. Among many applications enabled by IPSEC, a useful application is to connect a remote host to a corporate intranet via a security gateway, using IPSEC tunnel mode. This host is then configured in such a manner so as to provide it with a virtual presence on the internal network. This is accomplished in the following manner: A remote host on the Internet will connect to the security gateway and then establish an IPSEC tunnel to it. The remote host then interacts via the IPSEC tunnel with a DHCPv4 server which provides the remote host with an address from the corporate network address space. The remote host subsequently uses this as the source address for all interactions with corporate resources. Note that this implies that the corporate security gateway continues to recognize the host's original, routable IP address as the tunnel endpoint. The virtual identity assumed by the remote host when using the assigned address appears to the corporate network as though it were situated behind a security gateway bearing the original routable IP address. All the traffic between the remote host and the intranet will be carried over the IPSEC tunnel via the security gateway as shown below: corporate net +------------------+ | | externally | +--------+ | !~~~~~~~~~~! |+-------+ visible | | | | ! rmt host ! ||virtual| host | |security| |---! virtual ! || host | |--------|gateway/| | ! presence ! || |<================>| DHCP |----| !~~~~~~~~~~! |+-------+ |--------| Relay | | +------------------+ ^ +--------+ | +--------+ | |---| DHCPv4 | IPSEC tunnel | | server | with encapsulated | +--------+ traffic inside Patel, Aboba, Kelly & Gupta Standards Track [Page 4]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 This scenario assumes that the remote host already has Internet connectivity and the host Internet interface is appropriately configured. The mechanisms for configuration of the remote host's address for the Internet interface are well defined; i.e., PPP IP control protocol (IPCP), described in [4], DHCPv4, described in [3], and static addressing. The mechanisms for auto-configuration of the intranet are also standardized. It is also assumed that the remote host has knowledge of the location of the security gateway. This can be accomplished via DNS, using either A, KX, or SRV records. Typically the DHCPv4 server will not reside on the same machine as the security gateway, which will act as a DHCPv4 relay. In this case, the security gateway merely relays packets between the client and the DHCPv4 server, but does not request or renew addresses on the client's behalf. A typical configuration of the remote host in this application would use two addresses: 1) an interface to connect to the Internet (Internet interface), and 2) a virtual interface to connect to the intranet (intranet interface). The IP address of the Internet and intranet interfaces are used in the outer and inner headers of the IPSEC tunnel mode packet, respectively. 3.1. Configuration walk-through The configuration of the intranet interface of the IPSEC tunnel mode host is accomplished in the following steps: 1. The remote host establishes an IKE security association with the security gateway in a main mode or aggressive mode exchange. This IKE SA then serves to secure additional quick mode IPSEC SAs. 2. The remote host establishes a DHCP SA with the IPSEC tunnel mode server in a quick mode exchange. The DHCP SA is an IPSEC tunnel mode SA established to protect initial DHCPv4 traffic between the security gateway and the remote host. The DHCP SA MUST only be used for DHCP traffic. The details of how this SA is set up are described in Section 6.1. 3. DHCP messages are sent back and forth between the remote host and the DHCPv4 server. While other configurations are possible, typically the IPSEC tunnel server acts as a DHCPv4 relay. The traffic is protected between the remote host and the security gateway using the DHCP SA established in step 2. After the DHCP conversation completes, the remote host's intranet interface obtains an IP address as well as other configuration parameters. 4. The remote host MAY request deletion of the DHCP SA since future DHCP messages will be carried over a new IPSEC tunnel. Patel, Aboba, Kelly & Gupta Standards Track [Page 5]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 Alternatively, the remote host and the security gateway MAY continue to use the same SA for all subsequent traffic by adding temporary SPD selectors in the same manner as is provided for name ID types in [2]. 5. If a new IPSEC tunnel is required, the remote host establishes a tunnel mode SA to the security gateway in a quick mode exchange. In this case, the new address assigned via DHCPv4 SHOULD be used in the quick mode ID. At the end of the last step, the remote host is ready to communicate with the intranet using an IPSEC tunnel. All the IP traffic (including future DHCPv4 messages) between the remote host and the intranet are now tunneled over this IPSEC tunnel mode SA. Since the security parameters used for different SAs are based on the unique requirements of the remote host and the security gateway, they are not described in this document. The mechanisms described here work best when the VPN is implemented using a virtual interface. 4. Detailed description This section provides details relating to the messages exchanged during the setup and teardown of the DHCP SAs. Patel, Aboba, Kelly & Gupta Standards Track [Page 6]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 4.1. DHCPDISCOVER message processing The events begin with the remote host intranet interface generating a DHCPDISCOVER message. Details are described below: FIELD OCTETS DESCRIPTION ----- ------ ----------- op 1 Message op code / message type. 1 = BOOTREQUEST, 2 = BOOTREPLY htype 1 Hardware address type. Set to value (TBD) signifying an IPSEC tunnel mode virtual interface. hlen 1 Hardware address length hops 1 Client sets to zero, optionally used by relay agents when booting via a relay agent. xid 4 Transaction ID, a random number chosen by the client, used by the client and server to associate messages and responses between a client and a server. secs 2 Filled in by client, seconds elapsed since client began address acquisition or renewal process. flags 2 Flags ciaddr 4 Client IP address; only filled in if client is in BOUND, RENEW or REBINDING state. yiaddr 4 'your' (client) IP address. siaddr 4 IP address of next server to use in bootstrap; returned in DHCPOFFER, DHCPACK by server. giaddr 4 Security gateway IP address, used in booting via a relay agent. chaddr 16 Client hardware address. Should be unique. sname 64 Optional server host name, null terminated string. file 128 Boot file name, null terminated string; "generic" name or null in DHCPDISCOVER, fully qualified directory-path name in DHCPOFFER. options var Optional parameters field. Table 1: Description of fields in the DHCP message The htype value is set to the value TBD, signifying a virtual IPSEC tunnel mode interface, in order to enable the DHCP server to differentiate VPN from non-VPN requests. The chaddr field of the DHCPDISCOVER SHOULD include a unique identifier. The client MUST use the same chaddr field in all subsequent messages within the same DHCPv4 exchange. This permits the use of DHCP Relay load balancing as described in [19]. In addition, the chaddr SHOULD be persistent between reboots so that the DHCP server will be able to re-assign the same address if desired. Patel, Aboba, Kelly & Gupta Standards Track [Page 7]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 The hlen and chaddr fields SHOULD be determined as follows: 1. If one or more LAN interfaces are available, the hlen and chaddr fields SHOULD be determined from the active LAN interface with the lowest interface number. If no active LAN interface is available, then the parameters SHOULD be determined from the LAN interface with the lowest interface number. This enables the chaddr to be persistent between reboots, as long as the LAN interface hardware is not removed. 2. If there is no LAN interface, then the chaddr is not guaranteed to be persistent between reboots. The chaddr field SHOULD be determined by concatenating H'4000', the IPv4 address of the interface supplying network connectivity, and an additional octet. The H'4000' value indicates a locally administered unicast MAC address, thus guaranteeing that the constructed chaddr value will not conflict with a globally assigned value. The additional octet (which MAY represent an interface number) SHOULD be persistent between reboots, so that the chaddr value will be persistent across reboots if the assigned IPv4 address remains consistent. In order to deliver the DHCPDISCOVER packet from the intranet interface to the security gateway, an IKE Phase 1 SA is established between the Internet interface and the security gateway. A phase 2 (quick mode) DHCP SA tunnel mode SA is then established. The key lifetime for the DHCP SA SHOULD be on the order of minutes since it will only be temporary. The remote host SHOULD use an IDci payload of 0.0.0.0/UDP/port 68 in the quick mode exchange. The security gateway will use an IDcr payload of its own Internet address/UDP/port 67 The DHCP SA is established as a tunnel mode SA with filters set as follows: From client to server: Any to Any, destination: UDP port 67 From server to client: Any to Any, destination: UDP port 68 Note that these filters will work not only for a client without configuration, but also with a client that has previously obtained a configuration lease, and is attempting to renew it. In the latter case, the DHCP SA will initially be used to send a DHCPREQUEST rather than a DHCPDISCOVER message. The initial DHCPv4 message (DHCPDISCOVER or DHCPREQUEST) is then tunneled to the security gateway using the tunnel mode SA. Since the security gateway is acting as a DHCP relay, it will insert its address in the "giaddr" field, possibly adding a relay agent option [17], and will forward the message to one or more intranet DHCP servers. Patel, Aboba, Kelly & Gupta Standards Track [Page 8]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 4.2. DHCPOFFER message processing Typically, the security gateway will also store the xid and the chaddr gleaned from the DHCPDISCOVER in a table so as to be able to route the corresponding DHCPOFFER message(s) back to the remote host. 4.3. DHCPREQUEST message processing After the Internet interface has received the DHCPOFFER message, it forwards this to the intranet interface after IPSEC processing. The intranet interface then responds by creating a DHCPREQUEST message, which is tunneled to security gateway using the DHCP SA. 4.4. DHCPACK message processing The DHCPv4 server then replies with a DHCPACK or DHCPNAK message, which is forwarded down the DHCP SA by the security gateway. The remote host Internet interface then forwards the DHCPACK or DHCPNAK message to the intranet interface after IPSEC processing. To learn the IP address of the client in order to route packets to it, the security gateway will typically snoop the yiaddr field within the DHCPACK and plumb a corresponding route as part of DHCP relay processing. After processing of the DHCPACK, the intranet interface is configured and the Internet interface can establish a new IPSEC tunnel mode SA to the security gateway. The remote host may now delete the DHCP tunnel mode SA. All future DHCP messages sent by the client, including DHCPREQUEST, DHCPINFORM, DHCPDECLINE, and DHCPRELEASE messages will use the newly established VPN SA. Similarly, all DHCP messages subsequently sent by the DHCPv4 server will be forwarded by the security gateway (acting as a DHCP relay) using the IPSEC tunnel mode SA, including DHCPOFFER, DHCPACK, and DHCPNAK messages. It SHOULD be possible to configure the client to forward all Internet- bound traffic through the tunnel. While this adds overhead to round- trips between the client and the Internet, it provides some added security in return for this, in that the corporate security gateway may now filter traffic as it would if the remote host were physically located on the corporate network. 4.5. Configuration policy Several mechanisms can be used to enable IPSEC tunnel mode clients to be assigned different configurations. For example, clients may use the User Class Option [16] to request various configuration profiles. The DHCPv4 server may also take a number of other variables into account, including the chaddr; the client-identifier option; the DHCP relay option [17]; the vendor-class-identifier option; the vendor-specific information Patel, Aboba, Kelly & Gupta Standards Track [Page 9]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 option; the subnet selection option [15] or the host name option [18]. Conditional configuration of clients, described in [18], can be used to solve a number of problems, including assignment of options based on the client operating system; assignment of groups of clients to address ranges subsequently used to determine quality of service; allocation of special address ranges for IPSEC tunnel mode clients; special treatment for various hardware types, assignment of static routes to clients [20], etc. As noted in the security considerations, these mechanisms, while useful, do not enhance security since they can be evaded by a client choosing its own IP address. For use in DHCPv4 configuration of IPSEC tunnel mode, the client- identifier option SHOULD be included and set to something that is unique and persistent across reboots. Possibilities include: a) The htype/chaddr combination, if a LAN interface is present. b) The machine FQDN concatenated with an interface number. c) The user FQDN as determined from the user's NAI or certificate, concatenated with an interface number. 5. Appendix - IKECFG evaluation Alternatives to DHCPv4, such as ISAKMP CFG, described in [13], do not meet the basic requirements described in [21], nor do they provide the additional capabilities of DHCPv4. Basic configuration While ISAKMP CFG can provide for IP address assignment as well as configuration of a few additional parameters such as the DNS server and WINS server addresses, the rich configuration facilities of DHCPv4 are not supported. Past experience with similar configuration mechanisms within PPP IPCP [7] has taught us that it is not viable merely to support minimal configuration. Eventually, either much of the functionality embodied in the DHCPv4 options [5] is duplicated or support for DHCPINFORM [3] will be required. Address management integration Since IKECFG is not integrated with existing IP address management facilities, it is difficult to integrate it with policy management services that may be dependent on the user to IP address binding. Address pool management IKECFG does not provide a mechanism for the client to indicate Patel, Aboba, Kelly & Gupta Standards Track [Page 10]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 a preference for a particular address pool. This makes it difficult to support address pool management. Reconfiguration IKECFG does not support the concept of configuration leases or reconfiguration. Fail-over support Since IKECFG creates a separate pool of address state, it complicates the provisioning of network utility-class reliability, both in the IP address management system and in the security gateways themselves. Security and simplicity As past history with PPP IPCP demonstrates, once it is decided to provide non-integrated address management and configuration facilities within IKE, it will be difficult to limit the duplication of effort to address assignment. Instead, it will be tempting to also duplicate the configuration, authentication and fail-over facilities of DHCPv4. This duplication will greatly increase the scope of work, eventually compromising the security of IKE. Authentication While IKECFG can support mutual authentication of the IPSEC tunnel endpoints, it is difficult to integrate IKECFG with DHCPv4 authentication [6]. This is because the security gateway will not typically have access to the client credentials necessary to issue an DHCPv4 authentication option on the client's behalf. As a result, security gateways implementing IKECFG typically request allocation of an IP address on their own behalf, and then assign this to the client via IKECFG. Since IKECFG does not support the concept of an address lease, the security gateway will need to do the renewal itself. This complicates the renewal process. Since RFC 2131 [3] assumes that a DHCPREQUEST will not contain a filled in giaddr field when generated during RENEWING state, the DHCPACK will be sent directly to the client, which will not be expecting it. As a result, it is either necessary for the security gateway to add special code to avoid forwarding such packets, or to wait until REBINDING state. Since [3] does not specify that the giaddr field cannot be filled in when in the REBINDING state, the security gateway may put its own address in the giaddr field when in REBINDING state, thereby ensuring that it can receive the renewal response without Patel, Aboba, Kelly & Gupta Standards Track [Page 11]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 treating it as a special case. 6. References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [2] Atkinson, R., Kent, S., "Security Architecture for the Internet Protocol", RFC 2401, November 1998. [3] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, March 1997. [4] McGregor, G., "The PPP Internet Protocol Control Protocol (IPCP)", RFC 1332, May 1992. [5] Alexander, S., Droms, R., "DHCP Options and BOOTP Vendor Extensions", RFC 2132, March 1997. [6] Droms, R., Arbaugh, W., "Authentication for DHCP Messages", Internet draft (work in progress), draft-ietf-dhc- authentication-16.txt, January 2001. [7] Cobb, S., "PPP Internet Protocol Control Protocol Extensions for Name Server Addresses", RFC 1877, December 1995. [8] Droms, R., Kinnear, K., Stapp, M., Volz, B., Gonczi, S., Rabil, G., Dooley, M., Kapur, A., "DHCP Failover Protocol", Internet draft (work in progress), draft-ietf-dhc-failover-08.txt, July 2000. [9] Kent,S., Atkinson, R., "IP Authentication Header", RFC 2402, November 1998. [10] Kent,S., Atkinson, R., "IP Encapsulating Security Payload (ESP)", RFC 2406, November 1998. [11] Piper, D., "The Internet IP Security Domain of Interpretation of ISAKMP", RFC 2407, November 1998. [12] Harkins, D., Carrel, D., "The Internet Key Exchange (IKE)", RFC 2409, November 1998. [13] Dukes, D., Pereira, R., "The ISAKMP Configuration Method", Internet draft (work in progress), draft-dukes-ike-mode-cfg-00.txt, October 2000. Patel, Aboba, Kelly & Gupta Standards Track [Page 12]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 [14] De Schrijver, P., T'Joens, Y., Hublet, C., "Dynamic host configuration : DHCP reconfigure extension", Internet draft (work in progress), draft-ietf-dhc-pv4-reconfigure-02.txt, November 2000. [15] Waters, G., "The IPv4 Subnet Selection Option for DHCP", RFC 3011, November 2000. [16] Stump, G., Droms, R., Gu, Y., Vyaghrapuri, R., Demirtjis, A., Beser, B., Privat, J., "The User Class Option for DHCP", RFC 3004, November 2000. [17] Patrick, M., "DHCP Relay Agent Information Option", RFC 3046, January 2001. [18] Droms, R., and Lemon, T., The DHCP Handbook, Macmillan, Indianapolis, Indiana, 1999. [19] Volz, B., Gonczi, S., Lemon, T., Stevens, R., "DHC Load Balancing Algorithm", RFC 3074, February 2001. [20] Lemon, T., "The Classless Static Route Option for DHCP", Internet draft (work in progress), draft-ietf-dhc-csr-04.txt, February 2001. [21] Kelly, S., Ramamoorthi, S., "Requirements for IPSEC Remote Access Scenarios", Internet draft (work in progress), draft-ietf-ipsra- reqmts-03.txt, January 2001. 7. Security Considerations This protocol is secured using IPSEC, and as a result the DHCP packets flowing between the client and the security gateway are authenticated and integrity protected. However, since the security gateway acts as a DHCP Relay, no protection is afforded the DHCP packets in the portion of the path between the security gateway and the DHCP server, unless DHCP authentication is used. Note that authenticated DHCP cannot be used as an access control mechanism. This is because a client can always set its own IP address and thus evade any security measures based on DHCP authentication. As a result, the assigned address MUST NOT be depended upon for security. Instead, the security gateway can use other techniques such as instantiating packet filters or quick mode selectors on a per-tunnel basis. Patel, Aboba, Kelly & Gupta Standards Track [Page 13]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 8. IANA Considerations This draft requires that an htype value be allocated for use with IPSEC tunnel mode, as described in section 4.1. Note that DHCP relies on the arp-parameters registry for definition of both the hrd parameter in ARP and the htype parameter in BOOTP/DHCP. As a result, an assignment in the arp-parameters registry is required, even though IPSEC-DHCP will never use that parameter for ARP purposes, since conceptually BOOTP/DHCP and ARP share the arp-parameters registry. This draft does not create any new number spaces for IANA administration. 9. Acknowledgments This draft has been enriched by comments from John Richardson and Prakash Iyer of Intel, Gurdeep Pall and Peter Ford of Microsoft. 10. Authors' Addresses Baiju V. Patel Intel Corp, JF3-206 2511 NE 25th Ave Hillsboro, OR 97124 Phone: +1 503 264-2422 EMail: baiju.v.patel@intel.com Bernard Aboba Microsoft Corporation One Microsoft Way Redmond, WA 98052 Phone: +1 425 936-6605 EMail: bernarda@microsoft.com Scott Kelly RedCreek Communications 3900 Newpark Mall Road Newark, CA 94560 Phone: +1 510 745-3969 Email: skelly@redcreek.com Vipul Gupta Sun Microsystems, Inc. 901 San Antonio Rd. Palo Alto, CA 94303 Patel, Aboba, Kelly & Gupta Standards Track [Page 14]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 Phone: +1 650 786 3614 Fax: +1 650 786 6445 EMail: vipul.gupta@eng.sun.com 11. Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. Information on the IETF's procedures with respect to rights in standards-track and standards- related documentation can be found in BCP-11. Copies of claims of rights made available for publication and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementors or users of this specification can be obtained from the IETF Secretariat. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights which may cover technology that may be required to practice this standard. Please address the information to the IETF Executive Director. 12. Full Copyright Statement Copyright (C) The Internet Society (2001). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE." Patel, Aboba, Kelly & Gupta Standards Track [Page 15]
INTERNET-DRAFT DHCPv4 Config. of IPSEC Tunnel Mode 19 April 2001 13. Expiration Date This memo is filed as <draft-ietf-ipsec-dhcp-10.txt>, and expires November 1, 2001. Patel, Aboba, Kelly & Gupta Standards Track [Page 16]
