NSIS S. Thiruvengadam Internet-Draft H. Tschofenig Expires: April 23, 2005 Siemens F. Le Nokia October 23, 2004 Mobile IPv6 - NSIS Interaction for Firewall traversal draft-thiruvengadam-nsis-mip6-fw-01 Status of this Memo This document is an Internet-Draft and is subject to all provisions of section 3 of RFC 3667. By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents 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. This Internet-Draft will expire on April 23, 2005. Copyright Notice Copyright (C) The Internet Society (2004). Abstract Most of the firewalls deployed today are Mobile IPv6 unaware. Widespread Mobile IPv6 deployment is not possible unless Mobile IPv6 messages are allowed to pass through these firewalls. A signaling protocol is needed which can communicate with these firewalls and instruct them to bypass these Mobile IPv6 messages. The goal of this Thiruvengadam, et al. Expires April, 2005 [Page 1] Internet-Draft Mobile IPv6-NSIS October 2004 document is to describe the interaction between NSIS and Mobile IPv6 for successful deployment of Mobile IPv6. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Route Optimization . . . . . . . . . . . . . . . . . . . . . . 5 3.1 Correspondant Node behind a firewall . . . . . . . . . . . 5 3.2 Mobile Node behind a firewall . . . . . . . . . . . . . . 7 3.3 Home Agent behind a firewall . . . . . . . . . . . . . . . 9 4. Bi-directional tunneling . . . . . . . . . . . . . . . . . . . 12 4.1 Correspondant Node behind firewall . . . . . . . . . . . . 12 4.2 Mobile Node behind firewall . . . . . . . . . . . . . . . 13 4.3 Home Agent behind firewall . . . . . . . . . . . . . . . . 14 5. Triangular routing . . . . . . . . . . . . . . . . . . . . . . 16 5.1 Correspondant Node behind Firewall . . . . . . . . . . . . 16 5.2 Mobile Node behind Firewall . . . . . . . . . . . . . . . 17 5.3 Home Agent behind Firewall . . . . . . . . . . . . . . . . 18 6. Security Considerations . . . . . . . . . . . . . . . . . . . 20 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21 8. Open Issues . . . . . . . . . . . . . . . . . . . . . . . . . 22 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 23 9.1 Normative References . . . . . . . . . . . . . . . . . . . . 23 9.2 Informative References . . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 23 Intellectual Property and Copyright Statements . . . . . . . . 25 Thiruvengadam, et al. Expires April, 2005 [Page 2] Internet-Draft Mobile IPv6-NSIS October 2004 1. Introduction Route optimization, an integral part of Mobile IPv6 specification does not work with state of the art firewalls that employ stateful packet filtering. This problem is well described in [6]. The other modes of communication in Mobile IPv6 nameley bi-directional tunneling and triangular routing also do not work under some firewall placements. There is a need for identifying a signaling protocol that can install some firewall rules to allow these Mobile IPv6 messages to pass through. The NSIS NAT/FW NSLP described in [2], allows other protocols to establish, maintain and delete Middlebox state (NAT bindings and Firewall rules). We identify NSIS as possible solution to the aforementioned problem and describe the solution in detail. For every communication mode, we will consider the application of NSIS signaling for the following simple scenarios: o Correspondant Node (CN) behind a firewall o Mobile Node (MN) behind a firewall o Home Agent (HA) behind a firewall It is to be noted that a real scenario could include a combination of these cases. In all the scenarios, we assume that the Correspondant Node(CN), Mobile Node(MN) and the Firewalls(FW) are NSIS aware. For every NSIS message, we have also provided the NTLP flow-id which will be used to install the firewall policies. Thiruvengadam, et al. Expires April, 2005 [Page 3] Internet-Draft Mobile IPv6-NSIS October 2004 2. Terminology 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 [3]. Furthermore, we use the same terminology as in [1], [2], and [7]. Apart from this, we use some abbreviations to describe the flow-id of the NSIS messages: SA-Source Address, DA-Destination Address, SP-Source Port, DP-Destination Port and an asterisk is used as wild-card. Thiruvengadam, et al. Expires April, 2005 [Page 4] Internet-Draft Mobile IPv6-NSIS October 2004 3. Route Optimization In this communication mode, the CN and the MN deliver packets directly to each other. But before this, the MN has to perform Return Routability Test (RRT), where it has to send a home test init (HoTI) message (through the HA) and a Careof test init (CoTI) (directly) to the CN. The replies for these two messages home test (HoT) message (from the HA) and the Careof test (CoT) message (from the CN) are used to construct the binding-key which is used in the binding update procedure. 3.1 Correspondant Node behind a firewall In Figure 1, the CN is protected by a firewall that employs stateful packet filtering (SPF). The external MN and its associated HA are also shown in the figure. The MN is in its home network and is communicating with the CN. Here it is assumed that CN has initiated the communication and hence it has no problems with the SPF. The MN moves out of its home network and has to perform the return routability test (RRT) before sending the binding update to the CN. It sends a HoTI message through the HA to the CN and expects a HoT message from the CN in the same path. It also sends a CoTI message directly to the CN and expects CoT message in the same path from the CN. The SPF will only allow packets that belong to an existing session and hence both the packets (HoTI, CoTI) will be dropped as these packets are Mobile IPv6 packets and these packets have different header structure. The existing rules at the firewall might have been installed for some kind of data traffic. Thiruvengadam, et al. Expires April, 2005 [Page 5] Internet-Draft Mobile IPv6-NSIS October 2004 +----------------+ +----+ | | | HA | | | +----+ | | Home Agent | +----+ +----+ of MN | | CN | | FW | | +----+ +----+ | | +----+ | | | MN | | | +----+ +----------------+ External Mobile Network protected Node by a firewall Figure 1: CN behind the firewall As the RRT can not be executed, the firewalls rules have to be modified to allow these MIPv6 messages to go through. The MN initiates the NSIS session by sending a CREATE message to the CN. The FW may not necessarily know the MN and it may not be able to authenticate the MN. Hence it stores some relevant state regarding this 'firewall policy installation' request and waits for the CN's authorization. Once the CN approves the request, the FW will install the relevant policy requested by the MN. When the MN receives both the messages CoT and HoT, it will construct the binding key and perform binding update to the CN. Note, the signaling that was aforementioned was only to allow the Mobile IPv6 messages. Signaling to let the MIPv6 messages will be referred to as Signaling-C and signaling to let the data traffic pass through will be referred to as Signaling-D from hereon. The message flow for NSIS signaling (with MN as data sender) is shown in Figure 2. Note, only the message flow between MN and CN is shown in the diagram. For the Signaling-C CREATE message from MN to CN, the flow-id will be: SA: CoA, DA: CN. It is to be noted that policy rules that are to be installed to allow the HoTI and CoTI packets are different and the NI has to perform signaling twice. If the CN wants to continue sending data traffic (CN is the DS) to the new CoA, it can do so without any additional signaling. This is because the SPF will allow the traffic initiated by the nodes that it protects. But if the MN wants to continue sending data traffic (MN is the DS), it has to perform Signaling-D to install filter rules for data traffic. This will be referred to as Signaling-D from hereon. The possibility of combined signaling is a topic for further discussion. Thiruvengadam, et al. Expires April, 2005 [Page 6] Internet-Draft Mobile IPv6-NSIS October 2004 For the Signaling-D CREATE message from MN to CN, the flow-id will be: SA: CoA, DA: CN This solution works with the NSIS assumption that the firewalls will allow NSIS message from external network. However, operators might be reluctant to allow NSIS message from external network as this might lead to DoS attacks. This threat assumes significant importance if the NR is a mobile terminal. To avoid this, it is also possible to ask the CN to open pin-holes in the firewall on behalf of the MN. But this solution will not work in some scenarios due to routing asymmetry concerns as explained in [5]. +-----------------------+ | | Home Agent | +-----+ +----+ | | | | HA | | | | +----+ |+----+ | | || | | | CREATE-C +----+ || +--------<-----+ +---------<----------+ | || | SUCCEED | | | | || +-------->-----+ FW +--------->----------+ | || | | | CoTI | | || CN +--------<-----+ +---------<----------+ MN | || | CoT | | | | ||(DR)+-------->-----+ +--------->----------+(DS)| || | | | Binding update | | || +--------<-----+ +---------<----------+ | || | | | | | |+----+ +-----+ +----+ | | Mobile | | Node +-----------------------+ Network protected by a firewall Figure 2: NSIS signaling for CN behind the firewall 3.2 Mobile Node behind a firewall In Figure 3, the message flow for MN behind firewall scenario is shown (with CN as data sender). Here, all the messages initiated by Thiruvengadam, et al. Expires April, 2005 [Page 7] Internet-Draft Mobile IPv6-NSIS October 2004 the MN will be bypassed. Immediately after moving to a new network, the MN acquires a new CoA and it performs the Binding Update to the HA. The HoT message received by the MN is actually a tunneled message and as it does not belong to the session initiated by the MN, it will be dropped by the FW. Hence, either the HA could initiate NSIS signaling to MN and open pin-holes (only for NSIS aware HA) or the MN can open pin-holes for these messages to traverse (for NSIS unaware HA). The latter solution has additional concerns about routing asymmetry. For the Signaling-C CREATE message from HA to MN, the flow-id will be: SA: HA, DA: CoA Once the RRT is successfull, the binding update message is sent to the CN. If the MN wants to continue sending data traffic, then no NSIS signaling is needed at all for this scenario. However, if the CN wants to send data traffic, the relevant packet filter rules have to be installed at the firewall. Hence CN has to initiate Signaling-D to MN but this happens after the RRT. The MN has to perform binding update to the CN, conveying its new CoA. Then, if the CN wants to start the data transfer, it will send an NSLP message directly to the MN. The HA is not involved in this process (for this scenario). In scenarios where the network is protected by a single firewall, the MN can open pin-holes. It should be noted that the HA signals on behalf of the CN because the CN may not know that the MN is behind a firewall. The MN might move to different networks, some protected by a firewall. For the Signaling-D CREATE message from CN to MN, the flow-id will be: SA: CN, DA: CoA, SP: data application port, DP: data application port. Thiruvengadam, et al. Expires April, 2005 [Page 8] Internet-Draft Mobile IPv6-NSIS October 2004 Network protected +-------------------------+ | | | +-----+ +-----+ +----+ | | | | | | | | | |Binding Update| | | | | | |-------->-----+ +--------->----------+ | | | | | | Binding ACK | | | | |--------<-----+ +---------<----------+ | | | | | | | | | | MN | | FW | CREATE-C | HA | | | +--------<-----+ +---------<----------+ | | |(DS) | SUCCEED | | | | | | +-------->-----+ +--------->----------+ | | | | | | HoTI | | | | +-------->-----+ +--------->----------+ | | | | HoT | | | | | | +--------<-----+ +---------<----------+ | | | | | | | | | +-----+ +-----+ +----+ | | | | | ^ +-------------------------+ v | +----+ | CN | | | |(DR)| +----+ ----- = signaling traffic Correspondant node Figure 3: MN behind the firewall scenario 3.3 Home Agent behind a firewall This is a special case which requires the HA also to be NSIS aware. The HA should have NR (NSIS) responder capabilities. MN, after entering a new network, sends a binding update to the HA. But as it is initiated by the MN, it first has to install some filter rules in the FW before sending the binding update. The MN-HA binding update message is assumed to be IPsec protected. This might cause problems, as some primitive firewalls do not recognise IPsec traffic and hence drop the packets because of the Thiruvengadam, et al. Expires April, 2005 [Page 9] Internet-Draft Mobile IPv6-NSIS October 2004 absence of any transport header. Hence UDP encapsulation of IPsec traffic might be needed to alleviate this problem. The present firewalls use the SPI (Security Parameter Index) instead of the port numbers for IPsec traffic. The MN initiates the NSIS Signaling-C to create rules that will allow the binding update messages. Then it performs the binding update to the HA. For the Signaling-C CREATE message from MN to HA, the flow-id will be: SA: MN, DA: HA, SPIx. The authors are awaiting feedback from the MIP6 WG which is currently discussing the possibility of using Authentication Data field to carry Binding Update/Acknowledgement. This might be a possible alternative for Binding update protection. The firewall rules previously installed will not allow the HoTI message. Hence the MN has to install a different set of rules to allow these messages, by initiating another Signaling-C and then it sends teh HOTI message to HA. The HA will then send the HoTI to CN and obviously this message is allowed as it is initiated by the HA. The HoT message from CN to HA is also allowed by the SPF as it belongs to the session previously initiated by the HA. The HoT message from HA to MN is also allowed as it is initiated by the HA. The RRT completes successfully. For the Signaling-C CREATE message from MN to HA, the flow-id will be: SA: MN, DA: HA Detailed message flow (with MN as data sender) is shown in Figure 4. Note, only the interaction between HA and MN is shown in the figure. Thiruvengadam, et al. Expires April, 2005 [Page 10] Internet-Draft Mobile IPv6-NSIS October 2004 +------------------------+ +----+ | | | CN | | | |(DR)| | | +----+ | | | +----+ +-----+ +------------------+ | | | | | CREATE-C | +----+ | | | +--------<-----+ +---------<------|---<---+ | | | | | SUCCEED | | | | | | | | +-------->-----+ +--------->------|--->---+ | | | | | | | Binding update | | | | | | +--------<-----+ +---------<------|---<---+ | | | | HA | | FW | Binding ACK | | MN | | | | +-------->-----+ +--------->------|--->---+ | | | | | | | | |(DS)| | | | | | | CREATE-C | | | | | | +--------<-----+ +---------<------|---<---+ | | | | | SUCCEED | | | | | | | | +-------->-----+ +--------->------|--->---+ | | | | | | | HoTI | | | | | | +--------<-----+ +---------<------|---<---+ | | | | | | | HoT | | | | | | +-------->-----+ +--------->------|--->---+ | | | | | | | | | | | | +----+ +-----+ | +----+ | | | | | +------------------------+ +------------------+ HA protected by firewall Visited Network (Home Network) Figure 4: NSIS signaling for HA behind the firewall For the data traffic, there is no additional signaling as the MN sends data directly to CN and none of these networks (CN network and MN network) are protected by firewalls. This is applicable for both MN and CN as data senders. Thiruvengadam, et al. Expires April, 2005 [Page 11] Internet-Draft Mobile IPv6-NSIS October 2004 4. Bi-directional tunneling After roaming into a new network, the MN obtains a CoA in the visiting network. The MN registers itself with the HA. If CN is the data sender, it sends data to the HoA of the MN. It is routed to the Home Agent in a normal manner. HA encapsulates this packet and sends it to the MN. The MN decapsulates the packet. In the opposite direction, it is reverse tunneled to the Home Agent and then uses normal IP routing from there to the CN. 4.1 Correspondant Node behind firewall If we consider the scenario of the CN being protected by a firewall, there is no need for any signaling if the CN initiates data traffic. The CN sends the data traffic and hence the SPF will store relevant connection information and allow the packets in the reverse direction. If MN is the DS, then the HA has to initiate signaling-D, so that the firewall will allow the data traffic from the HA to CN. The message flow is shown in Figure 5. Thiruvengadam, et al. Expires April, 2005 [Page 12] Internet-Draft Mobile IPv6-NSIS October 2004 Protected network +-------------------------+ External Mobile | | Node | +-----+ +-----+ +----+ | | | | | | | | | | | | | | | | CN | | FW | CREATE-D | HA | | | +--------<-----+ +---------<----------+ | | |(DR) | SUCCEED | | | | | | +-------->-----+ +--------->----------+ | | | | | | | | | | | | | Data traffic | | | | +**************+ +********************+ | | | | | | | | | +-----+ +-----+ +----+ | | # +-------------------------+ # # +----+ | MN | |(DS)| ***** = Data traffic (both direction) +----+ ----- = signaling traffic Correspondant node ##### = tunneled traffic Figure 5: NSIS signaling for CN behind the firewall 4.2 Mobile Node behind firewall Consider the scenario where the MN is protected by a SPF. The CN is generally unaware that the MN is behind the firewall. This might happen because, as the MN roams it might find itself protected by a firewall in some networks and the CN is not conveyed this information. For this scenario, the HA is forced to do the NSIS signaling. This is unavoidable because the outer header (in the encapsulated packet) will have HA as the source address and the CoA as the destination address. The CN does not know the CoA of the MN and hence it has not chance of opening the pin-hole. Ultimately, the responsibility falls on the HA. If CN is the DS, then we would require an NSIS aware HA. Even though the MN had earlier initiated a connection for the purpose of binding update, new filter rules have to be installed to allow the tunneled data traffic. The message flow is shown in Figure 6. As explained earlier, it could be done either by NSIS aware HA or by the MN itself. The latter solution might require some topology assumptions. There is another important question to be resolved in this approach which is the timing of the Thiruvengadam, et al. Expires April, 2005 [Page 13] Internet-Draft Mobile IPv6-NSIS October 2004 signaling i.e., when the HA should signal to the MN. This is an open issue which needs further discussion. If the MN is the DS, no signaling is needed at all. For the Signaling-D CREATE message from HA to MN, the flow-id will be: SA: HA, DA: MN. Note these data messages for which we do signaling, are IP-in-IP tunneled messages and do not have any transport header. Protected network +-------------------------+ External Mobil | | Node | +-----+ +-----+ +----+ | | | | | | | | | |Binding update| | | | | | |-------->-----+ +--------->----------+ | | | | | | Binding ACK | | | | |--------<-----+ +---------<----------+ | | | | | | | | | | MN | | FW | CREATE-D | HA | | |(DR) +--------<-----+ +---------<----------+ | | | | SUCCEED | | | | | | +-------->-----+ +--------->----------+ | | | | | | | | | | | | | Data traffic | | | | +*******<******+ +*********<**********+ | | | | | | | | | +-----+ +-----+ +----+ | | * +-------------------------+ ^ * +----+ | CN | |(DS)| ***** = Data traffic +----+ ----- = signaling traffic Correspondant node Figure 6: NSIS signaling for MN behind the firewall 4.3 Home Agent behind firewall This is a special case which requires the HA also to be NSIS aware. The HA should have the capabilities of NR (NSIS responder). The CN has to open pin-holes in the FW protecting the HA by initiating Thiruvengadam, et al. Expires April, 2005 [Page 14] Internet-Draft Mobile IPv6-NSIS October 2004 Signaling-D. It is now allowed to send the data traffic through the FW. After intercepting the packet, the HA tunnels the packet and sends it to the MN. Figure 7 shows the message flow. For the Signaling-D CREATE message from CN to HA, the flow-id will be: SA: CN, DA: HoA, SP: Data application port, DP: Data application port. HA Network protected +-------------------------+ | | | +-----+ +-----+ +----+ | | | | | | | | | | | | CREATE-D | | | | |--------<-----+ +---------<----------+ CN | | | | SUCCEED | | |(DS)| | | |-------->-----+ +---------<----------+ | | | | | | Data traffic | | | | HA |********<*****+ FW +*********<**********+ | | | | | | | | | | | | | +----+ | | | | | | | | | | +----+ | | | | | | | | | +########>#####+ +#########>##########+ MN | | | | | | |(DR)| | | | | | | | | +-----+ +-----+ +----+ | | +-------------------------+ ----- = signaling traffic ***** = Data traffic ##### = tunneled packet Figure 7: NSIS signaling for HA behind the firewall Thiruvengadam, et al. Expires April, 2005 [Page 15] Internet-Draft Mobile IPv6-NSIS October 2004 5. Triangular routing The triangular routing differs from the bi-directional routing in the reverse direction only (MN to CN direction). In bi-directional routing, even though the MN obtains the address of the CN, it sends replies through the HA. This is avoided in triangular routing as the replies are directly sent to the CN. In this routing mode, the CN sends the packets with MN's HoA as the destination address and CN's address as the source address. The HA intercepts it and performs standard Mobile IP processing. The HA then sends the encapsulated packet to the MN which has HA's address as the source address and MN's address as the destination address. The MN decapsulates the packet and gets to know the address of the CN. The MN now sends the packets directly to the CN. 5.1 Correspondant Node behind Firewall Consider the scenario shown in Figure 8 where the CN is protected by a FW that has SPF functionality. If the CN is the DS, then the data traffic will be bypassed by the firewall. But if the MN is the DS, the firewall will not allow the data packets from the MN (packets in the reverse direction) as it does not belong to any connection that exists already. Hence, the MN has to initiate Signaling-D by sending the CREATE message to the CN and the FW will install the policies when it receives the SUCCEED/ERROR message. The CN could also install the relevant firewall rules for the MN in certain scenarios. Now the MN is allowed to communicate in the reverse direction. Thiruvengadam, et al. Expires April, 2005 [Page 16] Internet-Draft Mobile IPv6-NSIS October 2004 +-------------------------+ Home Agent | | of MN | +-----+ +-----+ +----+ | | | | | | HA | | | | | | | | | | | | | +----+ | | | | | | | | | | | | CN | | FW | | |(DR) | | | CREATE-D +-+--+ | | +--------<-----+ +---------<----------+ | | | | SUCCEED | | | | | | +-------->-----+ +--------->----------+ | | | | | | |(DS)| | | | | | Data traffic | MN | | | +********<*****+ +*********<**********+ | | | | | | | | | +-----+ +-----+ +----+ | | External Mobile | | Node +-------------------------+ Network protected ----- = signaling traffic ***** = Data traffic Figure 8: NSIS signaling for CN behind the firewall For the Signaling-D CREATE message from MN to CN, the flow-id will be: SA: MN, DA: CN, SP: Data application port, DP: Data application port. 5.2 Mobile Node behind Firewall This is a special case where the HA should be NSIS aware and should have NSIS Initiator (NI) capabilities. After mobility the MN sends a Binding update message to register its new CoA. If the CN is the DS, it sends the data to MN through HA. It is HA's responsibility to discover that the MN is behind a SPF and initiate signaling to MN to send the tunneled packets. The HA to MN signaling is completely transparent to CN. The CN is not aware of the fact that the MN is behind a firewall. The MN could also install the firewall rules in single firewall scenarios. For the Signaling-D CREATE message from HA to MN, the flow-id will be: SA: HA, DA: MN. Note these data messages for which we do signaling, are IP-in-IP tunneled messages and do not have any Thiruvengadam, et al. Expires April, 2005 [Page 17] Internet-Draft Mobile IPv6-NSIS October 2004 transport header. If the MN is the data sender, no further signaling is needed as the session is initiated by the MN. The message flow is shown in Figure 9. Network protected +-------------------------+ | | Home Agent | +-----+ +-----+ +----+ | | |Binding update| | | | | | |-------->-----+ +--------->----------+ | | | | | | Binding ACK | | | | |--------<-----+ +---------<----------+ | | | | | | CREATE-D | HA | | | +--------<-----+ +---------<----------+ | | | | SUCCEED | | | | | | +-------->-----+ +--------->----------+ | | | MN | | FW | Tunneled packets | | | |(DR) +########<#####+ +#########<##########+ | | | | | | | | | | | | | +----+ | | | | | * | | | | | ^ | | | | | * | | | | | +----+ | | | | | | CN | | +-----+ +-----+ |(DS)| | | +----+ +-------------------------+ Correspondant Node ----- = signaling traffic ***** = Data traffic ##### = tunneled traffic Figure 9: NSIS signaling for MN behind the firewall 5.3 Home Agent behind Firewall This is also a special case where the HA is assumed to be NSIS aware with NSIS Responder (NR) capabilities. The CN initiates NSIS signaling to open pin-holes in the FW protecting the HA. Then it can send the data traffic to HoA. The message flow is shown in Figure 10. Thiruvengadam, et al. Expires April, 2005 [Page 18] Internet-Draft Mobile IPv6-NSIS October 2004 For the Signaling-D CREATE message from HA to MN, the flow-id will be: SA: CN, DA: HoA, SP: Data application port, DP: Data application port. +------------------------+ | | | +----+ +-----+ | | | | | CREATE +----+ | | +--------<-----+ +---------<---------+ | | | | SUCCEED | | | | | | +-------->-----+ +--------->---------+ | | | HA | | FW | | | | | | | | DATA | CN | | | +******<*******+ +*********<*********+ | | | | | | +----+ | | | | | | | | | | | | | | | | | | | | Tunneled data +----+ | | +########>#####+ +#########>#########+ MN | | | | | | +----+ | +----+ +-----+ | | +------------------------+ HA protected by firewall (Home Network) ----- = signaling traffic ***** = Data traffic ##### = tunneled traffic Figure 10: NSIS signaling for HA behind the firewall Thiruvengadam, et al. Expires April, 2005 [Page 19] Internet-Draft Mobile IPv6-NSIS October 2004 6. Security Considerations The NAT/FW NSLP is in itself a very security sensitive service. A detailed description of possible threats and counter measures are described in [4]. In addition to that, the prospect of DoS when firewalls allow all NSIS signaling messages is dealt with in this draft. Thiruvengadam, et al. Expires April, 2005 [Page 20] Internet-Draft Mobile IPv6-NSIS October 2004 7. Acknowledgements Many parts of this documents are the result of some discussions within the NAT/firewall-NSLP-team including: Marcus Brunner, Miquel Martin, Martin Stiemerling, and Cedric Aoun. Thiruvengadam, et al. Expires April, 2005 [Page 21] Internet-Draft Mobile IPv6-NSIS October 2004 8. Open Issues o Do we need to combine Signaling-C and Signaling-D? o The timing of the HA-MN signaling i.e., when the HA should signal to the MN behind the firewall. Thiruvengadam, et al. Expires April, 2005 [Page 22] Internet-Draft Mobile IPv6-NSIS October 2004 9. References 9.1 Normative References [1] Johnson, D., Perkins, C. and J. Arkko, "Mobility Support in IPv6", RFC 3775, June 2004. [2] Stiemerling, M., "A NAT/Firewall NSIS Signaling Layer Protocol (NSLP)", draft-ietf-nsis-nslp-natfw-03 (work in progress), July 2004. [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", March 1997. 9.2 Informative References [4] Fessi, A., "Security Threats for the NAT/Firewall NSLP", draft-fessi-nsis-natfw-threats-01 (work in progress), July 2004. [5] Tschofenig, H., "Path-coupled NAT/Firewall Signaling Security Problems", draft-tschofenig-nsis-natfw-security-problems-00 (work in progress), July 2004. [6] Le, F., "Mobile IPv6 and Firewalls Problem statement", draft-ietf-mip6-firewalls-00 (work in progress), August 2004. [7] Brunner, M., "Requirements for Signaling Protocols", RFC 3726, April 2004. Authors' Addresses Srinath Thiruvengadam Siemens Otto-Hahn-Ring 6 Munich, Bayern 81739 Germany EMail: srinath@mytum.de Hannes Tschofenig Siemens Otto-Hahn-Ring 6 Munich, Bayern 81739 Germany EMail: Hannes.Tschofenig@siemens.com Thiruvengadam, et al. Expires April, 2005 [Page 23] Internet-Draft Mobile IPv6-NSIS October 2004 Franck Le Nokia Research Center 6000 Connection Drive, Irving Dallas, Texas 75063 USA EMail: franck.le@nokia.com Thiruvengadam, et al. Expires April, 2005 [Page 24] Internet-Draft Mobile IPv6-NSIS October 2004 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights 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; nor does it represent that it has made any independent effort to identify any such rights. 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Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM 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. Copyright Statement Copyright (C) The Internet Society (2004). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Thiruvengadam, et al. Expires April, 2005 [Page 25]