Discovering the Local Location Information Server (LIS)
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From: The IESG <firstname.lastname@example.org> To: IETF-Announce <email@example.com> Cc: Internet Architecture Board <firstname.lastname@example.org>, RFC Editor <email@example.com>, geopriv mailing list <firstname.lastname@example.org>, geopriv chair <email@example.com> Subject: Protocol Action: 'Discovering the Local Location Information Server (LIS)' to Proposed Standard The IESG has approved the following document: - 'Discovering the Local Location Information Server (LIS) ' <draft-ietf-geopriv-lis-discovery-15.txt> as a Proposed Standard This document is the product of the Geographic Location/Privacy Working Group. The IESG contact persons are Robert Sparks and Gonzalo Camarillo. A URL of this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-ietf-geopriv-lis-discovery-15.txt
Technical Summary: This document describes a method for the discovery of a Location Information Server (LIS) in the access network serving a device. Discovery of the correct LIS in the local access network is necessary for devices that wish to acquire location information from the network. The method described defines Dynamic Host Configuration Protocol (DHCP) options for IP versions 4 and 6 that specify a domain name. This domain name is then used as input to a URI-enabled NAPTR (U- NAPTR) resolution process. Working Group Summary: This document represents the consensus of the GEOPRIV working group. The original drafts of this document contained several different methods of performing LIS discovery. Through the working group review process, the DHCP/U-NAPTR method outlined in the current document was selected as the most appropriate for standardization at the current time. Document Quality: The key decision in drafting this document was to craft the LIS discovery mechanism in a near-identical fashion to the server discovery process outlined in RFCs 5222 and 5223, which had already been thoroughly vetted. RFC Editor Note OLD: U-NAPTR is entirely dependent on its inputs. In falsifying a domain name, an attacker avoids any later protections, bypassing them entirely. To ensure that the access network domain name DHCP option can be relied upon, preventing DHCP messages from being modified or spoofed by attackers is necessary. Physical or link layer security are commonplace methods that can reduce the possibility of such an attack within an access network; alternatively, DHCP authentication [RFC3118] can provide a degree of protection against modification or spoofing. The domain name that is used to authenticated the LIS is the domain name in the URI that is the result of the U-NAPTR resolution. Therefore, if an attacker were able to modify or spoof any of the DNS records used in the DDDS resolution, this URI could be replaced by an invalid URI. The application of DNS security (DNSSEC) [RFC4033] provides a means to limit attacks that rely on modification of the DNS records used in U-NAPTR resolution. Security considerations specific to U-NAPTR are described in more detail in [RFC4848]. An "https:" URI is authenticated using the method described in Section 3.1 of [RFC2818]. The domain name used for this authentication is the domain name in the URI resulting from U-NAPTR resolution, not the input domain name as in [RFC3958]. Using the domain name in the URI is more compatible with existing HTTP client software, which authenticate servers based on the domain name in the URI. NEW: The domain name that used to authenticate the LIS is the domain name input to the U-NAPTR process, not the output of that process [RFC3958], [RFC4848]. As a result, the results of DNS queries do not need integrity protection. An "https:" URI is authenticated using the method described in Section 3.1 of [RFC2818]. HTTP client implementations frequently do not provide a means to authenticate a based on a domain name other than the one indicated in the request URI, namely the U-NAPTR output. To avoid having to authenticate the LIS with a domain name that is different to the one used to identify it, a client MAY choose to reject URIs that contain a domain name that is different to the U-NAPTR input. To support endpoints that enforce the above restriction on URIs, network administrators SHOULD ensure that the domain name in the DHCP option is the same as the one contained in the resulting URI. Authentication of a LIS relies on the integrity of the domain name acquired from DHCP. An attacker that is able to falsify a domain name circumvents the protections provided. To ensure that the access network domain name DHCP option can be relied upon, preventing DHCP messages from being modified or spoofed by attackers is necessary. Physical or link layer security are commonplace methods that can reduce the possibility of such an attack within an access network. DHCP authentication [RFC3118] might also provide a degree of protection against modification or spoofing.