| Network Working Group | S. Bhandari |
| Internet-Draft | S. Gundavelli |
| Intended status: Standards Track | M. Grayson |
| Expires: July 7, 2016 | B. Volz |
| Cisco Systems | |
| J. Korhonen | |
| Broadcom Communications | |
| January 04, 2016 |
Access Network Identifier Option in DHCP
draft-ietf-dhc-access-network-identifier-11
This document specifies the format and mechanism that is to be used for encoding access network identifiers in DHCPv4 and DHCPv6 messages by defining new access network identifier options and sub-options.
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 July 7, 2016.
Copyright (c) 2016 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.
Access network identification (ANI) of a network device has a range of applications. For example the local mobility anchor in a Proxy Mobile IPv6 domain is able to provide access network and access operator specific handling or policing of the mobile node traffic using information about the access network to which the mobile node is attached.
This document specifies Dynamic Host Configuration Protocol for IPv4 (DHCPv4) [RFC2131] and Dynamic Host Configuration Protocol for IPv6 (DHCPv6) [RFC3315] options for access network identification that is added by Relay agent in the DHCPv4 or DHCPv6 messages towards the Server.
Dynamic Host Configuration Protocol (DHCP) relay agent aware of the access network and access operator add this information in the DHCP messages. This information can be used to provide differentiated services and policing of traffic based on the access network to which a client is attached. Examples of how this information can be used in mobile networks can be found in [RFC6757].
Proxy mobile IPv6 [RFC5213] can be used for supporting network-based mobility management in various types of network deployments. The network architectures, such as Service provider Wi-Fi access aggregation or, WLAN integrated mobile packet core are examples where Proxy Mobile IPv6 is a component of the overall architecture. Some of these architectures require the ability of the local mobility anchor (LMA) [RFC5213] to provide differentiated services and policing of traffic to the mobile nodes based on the access network to which they are attached. Policy systems in mobility architectures such as PCC [TS23203] and ANDSF [TS23402] in 3GPP system allow configuration of policy rules with conditions based on the access network information. For example, the service treatment for the mobile node's traffic may be different when they are attached to a access network owned by the home operator than when owned by a roaming partner. The service treatment can also be different based on the configured Service Set Identifiers (SSID) in case of IEEE 802.11 based access networks. Other examples of services include the operator's ability to apply tariff based on the location.
The PMIPv6 extension as specified in [RFC6757] defines PMIPv6 options to carry access network identifiers in PMIPv6 signaling from Mobile Access Gateway (MAG) to LMA. MAG can learn this information from DHCP options as inserted by DHCP Relay agent before MAG. If MAG relays DHCP messages to LMA as specified in [RFC5844] this information can be inserted by MAG towards LMA in the forwarded DHCP messages.
Figure 1 illustrates an example Proxy Mobile IPv6 deployment where Access Points (AP) acting as a DHCP relay agent inserts access network identifiers in DHCP messages relayed from the connected clients. The DHCP Server collocated on the mobile access gateway learns this information over DHCP and delivers the information elements related to the access network to the local mobility anchor over Proxy Mobile IPv6 signaling messages. In this example, the additional information could comprise the SSID of the used IEEE 802.11 network and the identities of the operators running the IEEE 802.11 access network infrastructure.
SSID: IETF-1
Operator-Id: provider1.example
+--+ DHCP
|AP|-------. {Access Specific Policies)
+--+ | _-----_ |
+-----+ _( )_ +-----+
| MAG |-=====( PMIPv6 )======-| LMA |-
+-----+ (_ Tunnel_) +-----+
+--+ DHCP | '-----'
|AP|-------'
+--+
SSID: IETF-2
Operator-Id: provider2.example
Access Networks attached to MAG
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 [RFC2119].
All the DHCP related terms used in this document are to be interpreted as defined in the Dynamic Host Configuration Protocol (DHCPv4) [RFC2131] and Dynamic Host Configuration Protocol for IPv6 (DHCPv6) [RFC3315] specifications. DHCP message refers to both DHCPv4 and DHCPv6 messages throughout this document.
All the mobility related terms used in this document are to be interpreted as defined in the Proxy Mobile IPv6 specifications [RFC5213] and [RFC5844]. Additionally, this document uses the following abbreviations:
Service Set Identifier (SSID)
Operator-Identifier
The Access Network Identifier carries information to identify the access network to which the client is attached. This information includes access technology type, network identifier, and access-network operator identifiers.
Relay agents that include Access Network Identifier information include one or more sub-options (see Section 4.1) in the Relay Agent Information option [RFC3046].
The access network identifier information will be defined in multiple sub-options, allocated from the DHCP Relay Agent Sub-Option Codes.
ANI Sub-options: The ANI Sub-options consists of a sequence of Sub-Option Code, Length, and Value tuples for each sub-option, encoded in the following manner:
SubOpt Len Sub-option Data
+------+------+------+------+------+------+--...-+------+
| code | N | s1 | s2 | s3 | s4 | | sN |
+------+------+------+------+------+------+--...-+------+
+=================+=======================================+ | SUB-OPTION CODE | SUB-OPTION DESCRIPTION | +=================+=======================================+ | <IANA-1> | Access Technology Type Sub-option | +=========================================================+ | <IANA-2> | Access Network Name Sub-option | +=========================================================+ | <IANA-3> | Access Point Name Sub-option | +=========================================================+ | <IANA-4> | Access Point BSSID Sub-option | +=========================================================+ | <IANA-5> | Operator-Identifier Sub-option | +=========================================================+ | <IANA-6> | Operator-Realm Sub-option | +=========================================================+
The initial assignment of DHCP access network identifier sub-options is as follows:
This sub-option is used for exchanging the type of the access technology of the network to which the client is attached. Its format is as follows:
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subopt Code | Length | Reserved | ATT |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
These sub-options are used for carrying the name of the access network (e.g., a SSID in case of IEEE 802.11 Access Network, or PLMN Identifier [TS23003] in case of 3GPP access) and Access Point name to which the client is attached. The format of these sub-options is defined the following sections.
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subopt Code | Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. .
. Network Name (e.g., SSID or PLMNID) .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subopt Code | Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. .
. Access-Point Name .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subopt Code | Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| Access-Point BSSID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Operator identifier sub-options can be used for carrying the operator identifier of the access network to which the client is attached. The format of these sub-options is defined below.
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subopt Code | Length | .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. Operator Enterprise ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Subopt Code | Length | |
|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. .
. Operator Realm .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Access Network Identifier options defined here may be added by the DHCPv6 Relay agent in Relay-forward messages.
+=================+=======================================+ | OPTION CODE | OPTION DESCRIPTION | +=================+=======================================+ | <IANA-7> | OPTION_ANI_ATT | +=========================================================+ | <IANA-8> | OPTION_ANI_NETWORK_NAME | +=========================================================+ | <IANA-9> | OPTION_ANI_AP_NAME | +=========================================================+ | <IANA-10> | OPTION_ANI_AP_BSSID | +=========================================================+ | <IANA-11> | OPTION_ANI_OPERATOR_ID | +=========================================================+ | <IANA-12> | OPTION_ANI_OPERATOR_REALM | +=========================================================+
This option is used for exchanging the type of the access technology the client is attached to the network. Its format is as follows:
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ANI_ATT | Option-Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | ATT |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
These options can be used for carrying the name of the access network (e.g., a SSID in case of IEEE 802.11 Access Network, or PLMN Identifier [TS23003] in case of 3GPP access) and Access Point name to which the client is attached. The format of these options is defined below.
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ANI_NETWORK_NAME | Option-Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. Network Name (e.g., SSID or PLMNID) .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ANI_AP_NAME | Option-Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. Access-Point Name .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ANI_AP_BSSID | Option-Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Access-Point BSSID |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Operator Identifier options can be used for carrying the operator identifier of the access network to which the client is attached. The format of these options is defined below.
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ANI_OPERATOR_ID | Option-Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Operator Enterprise ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_ANI_OPERATOR_REALM | Option-Len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. Operator Realm .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
DHCPv4 Relay Agents MAY include sub-options defined in section 4.2 through 4.4 in the Relay Agent Information option as defined in [RFC3046] before forwarding the DHCP message to provide information about the access network over which DHCP messages from the client is received.
DHCPv6 Relay Agents MAY include options defined in Section 5 in Relay-forward message when forwarding any DHCPv6 message type from clients to the servers to provide information about the access network over which DHCPv6 messages from the client is received.
If DHCPv4 server does not understand the option defined in Section 4 it MUST ignore the DHCPv4 Access Network Identifier option received. If the DHCPv4 server does not understand the received sub-option defined in sections 4.1 through 4.4 in the DHCPv4 Relay Agent Information option (82) it MUST ignore those sub-options only. If DHCPv4 Server is able to process the DHCPv4 Access Network Identifier sub-options defined in sections 4.1 through 4.4 received in DHCPv4 Relay Agent Information option, it MAY use this information for address pool selection policy decisions as per its configured policy. The DHCPv4 server MAY store this information along with the lease for logging and audit purpose. The DHCPv4 server MAY use the sub-options defined in sections 4.1 through section 4.4 inserted by the DHCPv4 relay agent in the Relay Agent Information option based on its configured policy.
If the DHCPv6 server receives the options defined in Section 5 and is configured to store or use the options defined in Section 5, it SHOULD look for the DHCPv6 Access Network identifier options in the Relay-forward message of the DHCPv6 relay agent(s) based on its configured policy. The server MAY use received ANI options for its address pool selection policy decisions as per its configured policy.
IANA is requested to assign Sub-option codes for the following DHCPv4 Sub-options from the "DHCP Relay Agent Sub-Option Codes" registry, <http://www.iana.org/assignments/bootp-dhcp-parameters>:
+=================+=======================================+ | SUB-OPTION CODE | SUB-OPTION DESCRIPTION | +=================+=======================================+ | <IANA-1> | Access Technology Type Sub-option | +=========================================================+ | <IANA-2> | Access Network Name Sub-option | +=========================================================+ | <IANA-3> | Access Point Name Sub-option | +=========================================================+ | <IANA-4> | Access Point BSSID Sub-option | +=========================================================+ | <IANA-5> | Operator-Identifier Sub-option | +=========================================================+ | <IANA-6> | Operator-Realm Sub-option | +=========================================================+
IANA is requested to assign option codes for the following DHCPv6 options from the "Option Codes registry for DHCPv6" registry <http://www.iana.org/assignments/dhcpv6-parameters>, as specified in [RFC3315]:
+=================+=======================================+ | OPTION CODE | OPTION DESCRIPTION | +=================+=======================================+ | <IANA-7> | OPTION_ANI_ATT | +=========================================================+ | <IANA-8> | OPTION_ANI_NETWORK_NAME | +=========================================================+ | <IANA-9> | OPTION_ANI_AP_NAME | +=========================================================+ | <IANA-10> | OPTION_ANI_AP_BSSID | +=========================================================+ | <IANA-11> | OPTION_ANI_OPERATOR_ID | +=========================================================+ | <IANA-12> | OPTION_ANI_OPERATOR_REALM | +=========================================================+
Since there is no privacy protection for DHCP messages, an eavesdropper who can monitor the link between the DHCP server and relay agent can discover access network information.
[RFC3118] and [RFC3315] describe many of the threats in using DHCP. [RFC3118] and [RFC3315] each provide a solution, the Authentication Option for DHCPv4 and DHCPv6 (respectively). However, neither of these options are in active use and therefore are not a viable mitigation option. DHCP itself is inherently insecure and thus link-layer confidentiality and integrity protection SHOULD be employed to reduce the risk of disclosure and tampering.
It is possible for a rogue DHCP relay agent to insert or overwrite with incorrect access network identifier options for malicious purposes. A DHCP client can also pose as a rogue DHCP relay agent by sending incorrect access network identifier options. While the introduction of fraudulent DHCP relay agent information options can be prevented by a perimeter defense that blocks these options unless the DHCP relay agent is trusted, a deeper defense using the authentication sub-option for DHCPv4 relay agent information option [RFC4030] SHOULD be deployed as well. DHCP server administrators are strongly advised to configure DHCP servers that use this option to communicate with their relay agents using IPsec security association(s) offering integrity protection, as described in Section 21.1 of [RFC3315].
The information elements that this draft is exposing is the client’s access-network information. These pertain to the access network to which the client is attached, such as Access Technology Type (Ex: WLAN, Ethernet…etc), Access Point Identity (Name, BSSID), Operator Id/Realm. In deployments where this information is considered secure and when such threat cannot be mitigated using IPsec [RFC4301] or other security protocols, then the administrators have to consider disabling the capability specified in this document on the DHCP entities.
The authors would like to thank Kim Kinnear, Ted Lemon, Gaurav Halwasia, Hidetoshi Yokota, Sheng Jiang and Francis Dupont for their valuable inputs. And, to Tomek Mrugalski for a thorough review of the document.
| [RFC2119] | Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997. |
| [RFC2131] | Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, DOI 10.17487/RFC2131, March 1997. |
| [RFC3046] | Patrick, M., "DHCP Relay Agent Information Option", RFC 3046, DOI 10.17487/RFC3046, January 2001. |
| [RFC3315] | Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C. and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 2003. |