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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NETWORK WORKING GROUP N. Williams 3 Internet-Draft Sun 4 Expires: May 22, 2008 November 19, 2007 6 GSS-API Internationalization and Domain-Based Service Names and Name 7 Type 8 draft-ietf-kitten-gssapi-domain-based-names-04.txt 10 Status of this Memo 12 By submitting this Internet-Draft, each author represents that any 13 applicable patent or other IPR claims of which he or she is aware 14 have been or will be disclosed, and any of which he or she becomes 15 aware will be disclosed, in accordance with Section 6 of BCP 79. 17 Internet-Drafts are working documents of the Internet Engineering 18 Task Force (IETF), its areas, and its working groups. Note that 19 other groups may also distribute working documents as Internet- 20 Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six months 23 and may be updated, replaced, or obsoleted by other documents at any 24 time. It is inappropriate to use Internet-Drafts as reference 25 material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt. 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html. 33 This Internet-Draft will expire on May 22, 2008. 35 Copyright Notice 37 Copyright (C) The IETF Trust (2007). 39 Abstract 41 This document describes domainname-based service principal names and 42 the corresponding name type for the Generic Security Service 43 Application Programming Interface (GSS-API). Internationalization of 44 the GSS-API is also covered. 46 Domain-based service names are similar to host-based service names, 47 but using a domain name (not necessarily an Internet domain name) in 48 addition to a hostname. The primary purpose of domain-based names is 49 to provide a measure of protection to applications that utilize 50 insecure service discovery protocols. This is achieved by providing 51 a way to name clustered services after the "domain" which they 52 service, thereby allowing their clients to authorize the service's 53 servers based on authentication of their service names. 55 Table of Contents 57 1. Conventions used in this document . . . . . . . . . . . . . 3 58 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 59 3. Name Type OID and Symbolic Name . . . . . . . . . . . . . . 5 60 4. Query and Display Syntaxes . . . . . . . . . . . . . . . . . 6 61 4.1. Examples of domain-based names . . . . . . . . . . . . . . . 6 62 5. Internationalization (I18N) considerations . . . . . . . . . 7 63 5.1. Importing internationalized names . . . . . . . . . . . . . 7 64 5.2. Displaying internationalized names . . . . . . . . . . . . . 7 65 6. Application protocol examples . . . . . . . . . . . . . . . 8 66 6.1. NFSv4 domain-wide namespace root server discovery . . . . . 8 67 6.2. LDAP server discovery . . . . . . . . . . . . . . . . . . . 8 68 7. Security Considerations . . . . . . . . . . . . . . . . . . 9 69 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 70 8.1. Normative References . . . . . . . . . . . . . . . . . . . . 10 71 8.2. Informative References . . . . . . . . . . . . . . . . . . . 10 72 Author's Address . . . . . . . . . . . . . . . . . . . . . . 12 73 Intellectual Property and Copyright Statements . . . . . . . 13 75 1. Conventions used in this document 77 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 78 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 79 document are to be interpreted as described in [RFC2119]. 81 2. Introduction 83 Some applications need to discover the names of servers for a 84 specific resource. Some common methods for server discovery are 85 insecure, e.g., queries for DNS [RFC1035] SRV resource records 86 [RFC2782] without using DNSSEC [RFC4033] and subject to attacks 87 whereby a client can be re-directed to incorrect and possibly 88 malicious servers. A client may even be re-directed to a server that 89 has credentials for itself and may thus authenticate itself to the 90 client, and yet it could be incorrect or malicious (because it has 91 been compromised, say). 93 Domain-based names allow for GSS-API [RFC2743] initiator applications 94 (clients) to authorize acceptor principals (servers) to serve the 95 resource for which the client used insecure server discovery without 96 either securing the server discovery method nor requiring an 97 additional protocol for server authorization -- either a discovered 98 server has credentials for authenticating the domain-based service 99 names that it is intended to respond to, or it does not. 100 Availability of valid credentials for authenticating domain-based 101 names embodies the authorization of a given server to a domain-wide 102 service. 104 A domain-based name consists of three required elements: 106 o a service name 108 o a domain name 110 o a hostname 112 The domain name and the hostname should be Domain Name System (DNS) 113 names, though domain-based names could be used in non-DNS 114 environments. Because of the use of DNS names we must also provide 115 for internationalization of the GSS-API. 117 Note that domain-based naming isn't new. According to a report to 118 the KITTEN WG mailing list there exists at least one implementation 119 of LDAP which uses domain-based service naming, and the DIGEST-MD5 120 HTTP/SASL mechanism [RFC2831] describes a similar notion (see section 121 2.1.2, description of the "serv-name" field of the digest-response). 123 3. Name Type OID and Symbolic Name 125 The new name type has an OID of 127 [NOTE: OID assignment to be made with IANA.] 129 {iso(1) org(3) dod(6) internet(1) security(5) nametypes(6) gss- 130 domain-based(5)} 132 The recommended symbolic name for this GSS-API name type is 133 "GSS_C_NT_DOMAINBASED_SERVICE". 135 4. Query and Display Syntaxes 137 There is a single name syntax for domain-based names. 139 The syntax is: 141 domain-based-name := 143 '@' '@' 145 Note that for Internet domain names the trailing '.' MUST NOT be 146 included in the hostname part of the display form GSS-API domain- 147 based MNs; hostnames MUST NOT contain '@'. 149 4.1. Examples of domain-based names 151 These examples are not normative: 153 o ldap@example.tld@ds1.example.tld 155 o nfs@example.tld@nfsroot1.example.tld 157 5. Internationalization (I18N) considerations 159 We introduce new versions of GSS_Import_name() and GSS_Display_name() 160 to better support Unicode. Additionally we provide for the use of 161 ACE-encoded DNS in the non-internationalized interfaces [RFC3490]. 163 5.1. Importing internationalized names 165 When the input_name_type parameter is the 166 GSS_C_NT_DOMAINBASED_SERVICE OID then GSS_Import_name() 167 implementations and GSS-API mechanisms MUST accept ACE-encoded 168 internationalized domain names in the hostname and domain name slots 169 of the given domain-based name string. 171 Support for non-ASCII internationalized domain names SHOULD be 172 provided through a new function, GSS_Import_name_utf8(), that 173 operates exactly like GSS_Import_name(), except that it MUST accept 174 internationalized domain names both, as UTF-8 strings and as ACE- 175 encoded strings via its input_name_string argument. 177 5.2. Displaying internationalized names 179 Implementations of GSS_Display_name() MUST only output US-ASCII or 180 ACE-encoded internationalized domain names in the hostname and domain 181 name slots of domain-based names (or mechanism names (MN) that 182 conform to the mechanism's form for domain-based names). 184 Support for non-ASCII internationalized domain names SHOULD be 185 provided through a new function, GSS_Display_name_utf8(), that 186 operates exactly like GSS_Display_name(), except that it outputs 187 UTF-8 strings via its name_string output argument. 188 GSS_Display_name_utf8() MUST NOT output ACE-encoded internationalized 189 domain names. 191 6. Application protocol examples 193 The following examples are not normative. They describe how the 194 author envisions two applications' use of domain-based names. 196 6.1. NFSv4 domain-wide namespace root server discovery 198 Work is ongoing to provide a method for constructing domain-wide 199 NFSv4 [RFC3530] filesystem namespaces where there is a single "root" 200 with one or more servers (replicas) and multiple filesystems glued 201 into the namespace through use of "referrals." Clients could then 202 construct a "global" namespace through use of the DNS domain 203 hierarchy. 205 Here clients would always know, from context, when they need to find 206 the root servers for a given DNS domain. Root server discovery would 207 be performed using DNS SRV RR lookups, without using DNSSEC where 208 DNSSEC has not been deployed. 210 When using RPCSEC_GSS [RFC2203] for security NFSv4 clients would then 211 use domain-based names to ensure that that the servers named in the 212 SRV RRs are in fact authorized to be the NFSv4 root servers for the 213 target domain. 215 6.2. LDAP server discovery 217 LDAP clients using the GSS-API through SASL too would benefit from 218 use of domain-based names to protect server discovery through 219 insecure DNS SRV RR lookups, much as described above. 221 Unlike NFSv4 clients, not all LDAP clients may always know from 222 context when they should use domain-based names. That's because 223 existing clients may use host-based naming to authenticate servers 224 discovered through SRV RR lookups. Changing such clients to use 225 domain-based naming when domain-based acceptor credentials have not 226 been deployed to LDAP servers, or when LDAP servers have not been 227 modified to allow use of domain-based naming, would break 228 interoperability. That is, there is a legacy server interoperability 229 issue here. Therefore LDAP clients may require additional 230 configuration at deployment time to enable (or disable) use of 231 domain-based naming. 233 Note: whether SASL [RFC4422] or its GSS-API bridges 234 [I-D.ietf-sasl-gssapi] [I-D.josefsson-sasl-gs2] require updates in 235 order allow use of domain-based names is not relevant to the theory 236 of how domain-based naming would protect LDAP clients' server 237 discovery. 239 7. Security Considerations 241 Use of GSS-API domain-based names may not be negotiable by some GSS- 242 API mechanisms, and some acceptors may not support GSS-API domain- 243 based names. In such cases initiators are left to fallback on the 244 use of hostbased names, in which case the initiators MUST also verify 245 that the acceptor's hostbased name is authorized to provide the given 246 service for the domain that the initiator had wanted. 248 The above security consideration also applies to all GSS-API 249 initiators who lack support for domain-based service names. 251 8. References 253 8.1. Normative References 255 [RFC1035] Mockapetris, P., "Domain names - implementation and 256 specification", STD 13, RFC 1035, November 1987. 258 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 259 Requirement Levels", BCP 14, RFC 2119, March 1997. 261 [RFC2743] Linn, J., "Generic Security Service Application Program 262 Interface Version 2, Update 1", RFC 2743, January 2000. 264 [RFC2782] Gulbrandsen, A., Vixie, P., and L. Esibov, "A DNS RR for 265 specifying the location of services (DNS SRV)", RFC 2782, 266 February 2000. 268 [RFC2831] Leach, P. and C. Newman, "Using Digest Authentication as a 269 SASL Mechanism", RFC 2831, May 2000. 271 [RFC3490] Faltstrom, P., Hoffman, P., and A. Costello, 272 "Internationalizing Domain Names in Applications (IDNA)", 273 RFC 3490, March 2003. 275 [RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S. 276 Rose, "DNS Security Introduction and Requirements", 277 RFC 4033, March 2005. 279 8.2. Informative References 281 [I-D.ietf-sasl-gssapi] 282 Melnikov, A., "The Kerberos V5 ("GSSAPI") SASL mechanism", 283 draft-ietf-sasl-gssapi-08 (work in progress), 284 September 2006. 286 [I-D.josefsson-sasl-gs2] 287 Josefsson, S., "Using GSS-API Mechanisms in SASL: The GS2 288 Mechanism Family", draft-josefsson-sasl-gs2-00 (work in 289 progress), November 2005. 291 [RFC2203] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol 292 Specification", RFC 2203, September 1997. 294 [RFC3530] Shepler, S., Callaghan, B., Robinson, D., Thurlow, R., 295 Beame, C., Eisler, M., and D. Noveck, "Network File System 296 (NFS) version 4 Protocol", RFC 3530, April 2003. 298 [RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and 299 Security Layer (SASL)", RFC 4422, June 2006. 301 Author's Address 303 Nicolas Williams 304 Sun Microsystems 305 5300 Riata Trace Ct 306 Austin, TX 78727 307 US 309 Email: Nicolas.Williams@sun.com 311 Full Copyright Statement 313 Copyright (C) The IETF Trust (2007). 315 This document is subject to the rights, licenses and restrictions 316 contained in BCP 78, and except as set forth therein, the authors 317 retain all their rights. 319 This document and the information contained herein are provided on an 320 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 321 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 322 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 323 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 324 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 325 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 327 Intellectual Property 329 The IETF takes no position regarding the validity or scope of any 330 Intellectual Property Rights or other rights that might be claimed to 331 pertain to the implementation or use of the technology described in 332 this document or the extent to which any license under such rights 333 might or might not be available; nor does it represent that it has 334 made any independent effort to identify any such rights. 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