IIJ & Arrcus

5147 Crystal Springs Bainbridge Island Washington 98110 United States of America randy@psg.com

NTT

Siriusdreef 70-72 Hoofddorp 2132 WT Netherlands massimo@ntt.net

Google

1600 Amphitheatre Parkway Mountain View CA 94043 United States of America warren@kumari.net

Vigil Security, LLC

516 Dranesville Road Herndon VA 20170 United States of America housley@vigilsec.com

geolocation geo-location RPSL This document specifies how to augment the Routing Policy Specification Language inetnum: class to refer specifically to geofeed data files and describes an optional scheme that uses the Resource Public Key Infrastructure to authenticate the geofeed datafiles.

Introduction Providers of Internet content and other services may wish to customize those services based on the geographic location of the user of the service. This is often done using the source IP address used to contact the service. Also, infrastructure and other services might wish to publish the locale of their services. defines geofeed, a syntax to associate geographic locales with IP addresses, but it does not specify how to find the relevant geofeed data given an IP address. This document specifies how to augment the Routing Policy Specification Language (RPSL) inetnum: class to refer specifically to geofeed data files and how to prudently use them. In all places inetnum: is used, inet6num: should also be assumed . The reader may find and informative, and certainly more verbose, descriptions of the inetnum: database classes. An optional utterly awesome but slightly complex means for authenticating geofeed data is also defined. This document obsoletes . Changes from include the following:

• It is no longer assumed that a geofeed file is a CSV, comma separated value list.
• RIPE has implemented the geofeed: attribute.
• Allow, but discourage, an inetnum: to have both a geofeed remarks: attribute and a geofeed: attribute.
• Stress that authenticating geofeed data is optional.
• IP Address Delegation extensions must not use "inherit".
• If geofeed data are present, ignore geographic location hints in other data.

Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Geofeed Files Geofeed files are described in . They provide a facility for an IP address resource "owner" to associate those IP addresses to geographic locales. Content providers and other parties who wish to locate an IP address to a geographic locale need to find the relevant geofeed data. In , this document specifies how to find the relevant geofeed file given an IP address. Geofeed data for large providers with significant horizontal scale and high granularity can be quite large. The size of a file can be even larger if an unsigned geofeed file combines data for many prefixes, if dual IPv4/IPv6 spaces are represented, etc. Geofeed data do have privacy considerations (see ); this process makes bulk access to those data easier. This document also suggests an optional signature to strongly authenticate the data in the geofeed files.

inetnum: Class The original RPSL specifications starting with , , and a trail of subsequent documents were written by the RIPE community. The IETF standardized RPSL in and . Since then, it has been modified and extensively enhanced in the Regional Internet Registry (RIR) community, mostly by RIPE . Currently, change control effectively lies in the operator community. The RPSL, and and used by the Regional Internet Registries (RIRs), specify the inetnum: database class. Each of these objects describes an IP address range and its attributes. The inetnum: objects form a hierarchy ordered on the address space. Ideally, RPSL would be augmented to define a new RPSL geofeed: attribute in the inetnum: class. Currently, this has been implemented in only the RIPE Database. Until such time, this document defines the syntax of a Geofeed remarks: attribute, which contains an HTTPS URL of a geofeed file. The format of the inetnum: geofeed remarks: attribute MUST be as in this example, "remarks: Geofeed ", where the token "Geofeed " MUST be case sensitive, followed by a URL that will vary, but it MUST refer only to a single geofeed file. While we leave global agreement of RPSL modification to the relevant parties, we specify that a proper geofeed: attribute in the inetnum: class MUST be "geofeed:" and MUST be followed by a single URL that will vary, but it MUST refer only to a single geofeed file. Registries MAY, for the interim, provide a mix of the remarks: attribute form and the geofeed: attribute form. The URL uses HTTPS, so the WebPKI provides authentication, integrity, and confidentiality for the fetched geofeed file. However, the WebPKI can not provide authentication of IP address space assignment. In contrast, the RPKI (see ) can be used to authenticate IP space assignment; see optional authentication in . Until all producers of inetnum: objects, i.e., the RIRs, state that they have migrated to supporting a geofeed: attribute, consumers looking at inetnum: objects to find geofeed URLs MUST be able to consume both the remarks: and geofeed: forms. The migration not only implies that the RIRs support the geofeed: attribute, but that all registrants have migrated any inetnum: objects from remarks: to geofeed: attributes. Any particular inetnum: object SHOULD have, at most, one geofeed reference, whether a remarks: or a proper geofeed: attribute when it is implemented. If there is more than one, the geofeed: attribute SHOULD be used. For inetnum:s covering the same address range, or an inetnum: with both remarks: and geofeed: attributes, a signed geofeed file SHOULD be preferred over an unsigned file. If a geofeed file describes multiple disjoint ranges of IP address space, there are likely to be geofeed references from multiple inetnum: objects. Files with geofeed references from multiple inetnum: objects are not compatible with the signing procedure in . An unsigned, and only an unsigned, geofeed file MAY be referenced by multiple inetnum:s and MAY contain prefixes from more than one registry. When geofeed references are provided by multiple inetnum: objects that have identical address ranges, then the geofeed reference on the inetnum: with the most recent last-modified: attribute SHOULD be preferred. As inetnum: objects form a hierarchy, geofeed references SHOULD be at the lowest applicable inetnum: object covering the relevant address ranges in the referenced geofeed file. When fetching, the most specific inetnum: object with a geofeed reference MUST be used. It is significant that geofeed data may have finer granularity than the inetnum: that refers to them. For example, an INETNUM object for an address range P could refer to a geofeed file in which P has been subdivided into one or more longer prefixes. Currently, the registry data published by ARIN are not the same RPSL as that of the other registries (see for a survey of the WHOIS Tower of Babel); therefore, when fetching from ARIN via FTP , WHOIS , the Registration Data Access Protocol (RDAP) , etc., the "NetRange" attribute/key MUST be treated as "inetnum", and the "Comment" attribute MUST be treated as "remarks".

Authenticating Geofeed Data (Optional) The question arises whether a particular geofeed data set is valid, i.e., is authorized by the "owner" of the IP address space and is authoritative in some sense. The inetnum: that points to the geofeed file provides some assurance. Unfortunately, the RPSL in some repositories is weakly authenticated at best. An approach where RPSL was signed per would be good, except it would have to be deployed by all RPSL registries, and there is a fair number of them. A single optional authenticator MAY be appended to a geofeed file. It is a digest of the main body of the file signed by the private key of the relevant RPKI certificate for a covering address range. One needs a format that bundles the relevant RPKI certificate with the signature of the geofeed text. The canonicalization procedure converts the data from their internal character representation to the UTF-8 character encoding, and the <CRLF> sequence MUST be used to denote the end of a line of text. A blank line is represented solely by the <CRLF> sequence. For robustness, any non-printable characters MUST NOT be changed by canonicalization. Trailing blank lines MUST NOT appear at the end of the file. That is, the file must not end with multiple consecutive <CRLF> sequences. Any end-of-file marker used by an operating system is not considered to be part of the file content. When present, such end-of-file markers MUST NOT be processed by the digital signature algorithm. Should the authenticator be syntactically incorrect per the above, the authenticator is invalid. Borrowing detached signatures from , after file canonicalization, the Cryptographic Message Syntax (CMS) would be used to create a detached DER-encoded signature that is then padded BASE64 encoded (as per ) and line wrapped to 72 or fewer characters. The same digest algorithm MUST be used for calculating the message digest on content being signed, which is the geofeed file, and for calculating the message digest on the SignerInfo SignedAttributes . The message digest algorithm identifier MUST appear in both the SignedData DigestAlgorithmIdentifiers and the SignerInfo DigestAlgorithmIdentifier . The address range of the signing certificate MUST cover all prefixes in the geofeed file it signs. An address range A "covers" address range B if the range of B is identical to or a subset of A. "Address range" is used here because inetnum: objects and RPKI certificates need not align on Classless Inter-Domain Routing (CIDR) prefix boundaries, while those of the lines in a geofeed file do. As the signer specifies the covered RPKI resources relevant to the signature, the RPKI certificate covering the inetnum: object's address range is included in the CMS SignedData certificates field. Identifying the private key associated with the certificate and getting the department that controls the private key (which might be trapped in a Hardware Security Module (HSM)) to sign the CMS blob is left as an exercise for the implementor. On the other hand, verifying the signature requires no complexity; the certificate, which can be validated in the public RPKI, has the needed public key. The trust anchors for the RIRs are expected to already be available to the party performing signature validation. Validation of the CMS signature on the geofeed file involves:

1. Obtaining the signer's certificate from the CMS SignedData CertificateSet . The certificate SubjectKeyIdentifier extension MUST match the SubjectKeyIdentifier in the CMS SignerInfo SignerIdentifier . If the key identifiers do not match, then validation MUST fail. Validation of the signer's certificate MUST ensure that it is part of the current manifest and that the resources are covered by the RPKI certificate.
2. Constructing the certification path for the signer's certificate. All of the needed certificates are expected to be readily available in the RPKI repository. The certification path MUST be valid according to the validation algorithm in and the additional checks specified in associated with the IP Address Delegation certificate extension and the Autonomous System Identifier Delegation certificate extension. If certification path validation is unsuccessful, then validation MUST fail.
3. Validating the CMS SignedData as specified in using the public key from the validated signer's certificate. If the signature validation is unsuccessful, then validation MUST fail.
4. Verifying that the IP Address Delegation certificate extension covers all of the address ranges of the geofeed file. If all of the address ranges are not covered, then validation MUST fail.

All of these steps MUST be successful to consider the geofeed file signature as valid. As the signer specifies the covered RPKI resources relevant to the signature, the RPKI certificate covering the inetnum: object's address range is included in the CMS SignedData certificates field . An IP Address Delegation extension using "inherit" would complicate processing. The implementation would have to build the certification path from the end-entity to the trust anchor, then validate the path from the trust anchor to the end-entity, and then the parameter would have to be remembered when the validated public key was used to validate a signature on a CMS object. Having to remember things from certification path validation for use with CMS object processing is too hard. And, the certificates do not get that much bigger by repeating the information. Therefore an extension using "inherit" MUST NOT be used. This is consistent with other RPKI signed objects. Identifying the private key associated with the certificate and getting the department with the Hardware Security Module (HSM) to sign the CMS blob is left as an exercise for the implementor. On the other hand, verifying the signature requires no complexity; the certificate, which can be validated in the public RPKI, has the needed public key. The appendix MUST be hidden as a series of "#" comments at the end of the geofeed file. The following is a cryptographically incorrect, albeit simple, example. A correct and full example is in . The signature does not cover the signature lines. The bracketing "# RPKI Signature:" and "# End Signature:" MUST be present following the model as shown. Their IP address range MUST match that of the inetnum: URL followed to the file. describes and provides code for a CMS profile for a general purpose listing of checksums (a "checklist") for use with the Resource Public Key Infrastructure (RPKI). It provides usable, albeit complex, code to sign geofeed files. describes a CMS profile for a general purpose Resource Tagged Attestation (RTA) based on the RPKI. While this is expected to become applicable in the long run, for the purposes of this document, a self-signed root trust anchor is used.

Operational Considerations To create the needed inetnum: objects, an operator wishing to register the location of their geofeed file needs to coordinate with their Regional Internet Registry (RIR) or National Internet Registry (NIR) and/or any provider Local Internet Registry (LIR) that has assigned address ranges to them. RIRs/NIRs provide means for assignees to create and maintain inetnum: objects. They also provide means of assigning or sub-assigning IP address resources and allowing the assignee to create WHOIS data, including inetnum: objects, thereby referring to geofeed files. The geofeed files MUST be published via and fetched using HTTPS . When using data from a geofeed file, one MUST ignore data outside the referring inetnum: object's inetnum: attribute address range. If and only if the geofeed file is not signed per , then multiple inetnum: objects MAY refer to the same geofeed file, and the consumer MUST use only lines in the geofeed file where the prefix is covered by the address range of the inetnum: object's URL it has followed. If the geofeed file is signed, and the signer's certificate changes, the signature in the geofeed file MUST be updated. It is good key hygiene to use a given key for only one purpose. To dedicate a signing private key for signing a geofeed file, an RPKI Certification Authority (CA) may issue a subordinate certificate exclusively for the purpose shown in . To minimize the load on RIR WHOIS services, use of the RIR's FTP services SHOULD be used for large-scale access to gather geofeed URLs. This also provides bulk access instead of fetching by brute-force search through the IP space. Harvesting and publishing aggregated geofeed data outside of the RPSL model should be avoided as it can have the effect that more specifics from one aggregatee could undesirably affect the less specifics of a different aggregatee. The validation model in Section handles this issue within the RPSL model. Currently, geolocation providers have bulk WHOIS data access at all the RIRs. An anonymized version of such data is openly available for all RIRs except ARIN, which requires an authorization. However, for users without such authorization, the same result can be achieved with extra RDAP effort. There is open-source code to pass over such data across all RIRs, collect all geofeed references, and process them . Geofeed data are orthogonal to geographic attributes in the inetnum:. Attributes such as country: tend to be administrative, and not deployment specific. Consider large, possibly global, providers with headquarters very far from most of their deployments. To prevent undue load on RPSL and geofeed servers, entity-fetching geofeed data using these mechanisms MUST NOT do frequent real-time lookups. suggests use of the HTTP Expires header to signal when geofeed data should be refetched. As the data change very infrequently, in the absence of such an HTTP Header signal, collectors SHOULD NOT fetch more frequently than weekly. It would be polite not to fetch at magic times such as midnight UTC, the first of the month, etc., because too many others are likely to do the same. If geofeed data are specified, either as a geofeed: attribute or in a geofeed remarks: attribute, other geographic hints such as country:, DNS geoloc RRsets, etc., for that address range should be ignored.

Privacy Considerations geofeed data may reveal the approximate location of an IP address, which might in turn reveal the approximate location of an individual user. Unfortunately, provides no privacy guidance on avoiding or ameliorating possible damage due to this exposure of the user. In publishing pointers to geofeed files as described in this document, the operator should be aware of this exposure in geofeed data and be cautious. All the privacy considerations of apply to this document. Where provided the ability to publish location data, this document makes bulk access to those data readily available. This is a goal, not an accident.

Security Considerations It is generally prudent for a consumer of geofeed data to also use other sources to cross-validate the data. All the security considerations of apply here as well. The consumer of geofeed data SHOULD fetch and process the data themselves. Importing datasets produced and/or processed by a third-party places ill-advised trust in the third-party. As mentioned in , some RPSL repositories have weak, if any, authentication. This allows spoofing of inetnum: objects pointing to malicious geofeed files. suggests an unfortunately complex method for stronger authentication based on the RPKI. For example, if an inetnum: for a wide address range (e.g., a /16) points to an RPKI-signed geofeed file, a customer or attacker could publish an unsigned equal or narrower (e.g., a /24) inetnum: in a WHOIS registry that has weak authorization, abusing the rule that the most-specific inetnum: object with a geofeed reference MUST be used. If signatures were mandatory, the above attack would be stymied, but of course that is not happening anytime soon. The RPSL providers have had to throttle fetching from their servers due to too-frequent queries. Usually, they throttle by the querying IP address or block. Similar defenses will likely need to be deployed by geofeed file servers.

IANA Considerations There are no new actions needed by the IANA.

RIPE NCC RIPE NCC RIPE NCC RIPE NCC RIPE NCC commit 5f557a4

Example This appendix provides an example that includes a trust anchor, a CA certificate subordinate to the trust anchor, an end-entity certificate subordinate to the CA for signing the geofeed, and a detached signature. The trust anchor is represented by a self-signed certificate. As usual in the RPKI, the trust anchor has authority over all IPv4 address blocks, all IPv6 address blocks, and all Autonomous System (AS) numbers. The CA certificate is issued by the trust anchor. This certificate grants authority over one IPv4 address block (192.0.2.0/24) and two AS numbers (64496 and 64497). The end-entity certificate is issued by the CA. This certificate grants signature authority for one IPv4 address block (192.0.2.0/24). Signature authority for AS numbers is not needed for geofeed data signatures, so no AS numbers are included in the certificate. The end-entity certificate is displayed below in detail. For brevity, the other two certificates are not. To allow reproduction of the signature results, the end-entity private key is provided. For brevity, the other two private keys are not. Signing of "192.0.2.0/24,US,WA,Seattle," (terminated by CR and LF) yields the following detached CMS signature.

Acknowledgments Thanks to for CMS and detached signature clue, for the first and substantial external review, and who was too shy to agree to coauthorship. Additionally, we express our gratitude to early implementors, including ; ; ; , who also found an ASN.1 'inherit' issue; and . Also, thanks to the following geolocation providers who are consuming geofeeds with this described solution: (ipdata.co), (ipinfo.io), and (bigdatacloud.com). For an amazing number of helpful reviews, we thank , , , (INTDIR), , (SECDIR), , , (GENART), , , and .