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diff --git a/doc/rfc/rfc4559.txt b/doc/rfc/rfc4559.txt new file mode 100644 index 0000000..fa63f62 --- /dev/null +++ b/doc/rfc/rfc4559.txt @@ -0,0 +1,451 @@ + + + + + + +Network Working Group K. Jaganathan +Request for Comments: 4559 L. Zhu +Category: Informational J. Brezak + Microsoft Corporation + June 2006 + + + SPNEGO-based Kerberos and NTLM HTTP Authentication + in Microsoft Windows + + +Status of This Memo + + This memo provides information for the Internet community. It does + not specify an Internet standard of any kind. Distribution of this + memo is unlimited. + +Copyright Notice + + Copyright (C) The Internet Society (2006). + +Abstract + + This document describes how the Microsoft Internet Explorer (MSIE) + and Internet Information Services (IIS) incorporated in Microsoft + Windows 2000 use Kerberos for security enhancements of web + transactions. The Hypertext Transport Protocol (HTTP) auth-scheme of + "negotiate" is defined here; when the negotiation results in the + selection of Kerberos, the security services of authentication and, + optionally, impersonation (the IIS server assumes the windows + identity of the principal that has been authenticated) are performed. + This document explains how HTTP authentication utilizes the Simple + and Protected GSS-API Negotiation mechanism. Details of Simple And + Protected Negotiate (SPNEGO) implementation are not provided in this + document. + +Table of Contents + + 1. Introduction ....................................................2 + 2. Conventions Used in This Document ...............................2 + 3. Access Authentication ...........................................2 + 3.1. Reliance on the HTTP/1.1 Specification .....................2 + 4. HTTP Negotiate Authentication Scheme ............................2 + 4.1. The WWW-Authenticate Response Header .......................2 + 5. Negotiate Operation Example .....................................4 + 6. Security Considerations .........................................5 + 7. Normative References ............................................6 + + + + +Jaganathan, et al. Informational [Page 1] + +RFC 4559 HTTP Authentication in Microsoft Windows June 2006 + + +1. Introduction + + Microsoft has provided support for Kerberos authentication in + Microsoft Internet Explorer (MSIE) and Internet Information Services + (IIS), in addition to other mechanisms. This provides the benefits + of the Kerberos v5 protocol for Web applications. + + Support for Kerberos authentication is based on other previously + defined mechanisms, such as SPNEGO Simple And Protected Negotiate + (SPNEGO) [RFC4178] and the Generic Security Services Application + Program Interface(GSSAPI). + +2. Conventions Used in This Document + + The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", + "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to + be interpreted as described in [RFC2119]. + +3. Access Authentication + +3.1. Reliance on the HTTP/1.1 Specification + + This specification is a companion to the HTTP/1.1 specification + [RFC2616], and it builds on the authentication mechanisms defined in + [RFC2617]. It uses the augmented BNF section of that document (2.1), + and it relies on both the non-terminals defined in that document and + other aspects of the HTTP/1.1 specification. + +4. HTTP Negotiate Authentication Scheme + + Use of Kerberos is wrapped in an HTTP auth-scheme of "Negotiate". + The auth-params exchanged use data formats defined for use with the + GSS-API [RFC2743]. In particular, they follow the formats set for + the SPNEGO [RFC4178] and Kerberos [RFC4121] mechanisms for GSSAPI. + The "Negotiate" auth-scheme calls for the use of SPNEGO GSSAPI tokens + that the specific mechanism type specifies. + + The current implementation of this protocol is limited to the use of + SPNEGO with the Kerberos and Microsoft(NT Lan Manager) NTLM + protocols. + +4.1. The WWW-Authenticate Response Header + + If the server receives a request for an access-protected object, and + if an acceptable Authorization header has not been sent, the server + responds with a "401 Unauthorized" status code, and a "WWW- + Authenticate:" header as per the framework described in [RFC2616]. + The initial WWW-Authenticate header will not carry any gssapi-data. + + + +Jaganathan, et al. Informational [Page 2] + +RFC 4559 HTTP Authentication in Microsoft Windows June 2006 + + + The negotiate scheme will operate as follows: + + challenge = "Negotiate" auth-data + auth-data = 1#( [gssapi-data] ) + + The meanings of the values of the directives used above are as + follows: + + gssapi-data + + If the gss_accept_security_context returns a token for the client, + this directive contains the base64 encoding of an + initialContextToken, as defined in [RFC2743]. This is not present in + the initial response from the server. + + A status code 200 status response can also carry a "WWW-Authenticate" + response header containing the final leg of an authentication. In + this case, the gssapi-data will be present. Before using the + contents of the response, the gssapi-data should be processed by + gss_init_security_context to determine the state of the security + context. If this function indicates success, the response can be + used by the application. Otherwise, an appropriate action, based on + the authentication status, should be taken. + + For example, the authentication could have failed on the final leg if + mutual authentication was requested and the server was not able to + prove its identity. In this case, the returned results are suspect. + It is not always possible to mutually authenticate the server before + the HTTP operation. POST methods are in this category. + + When the Kerberos Version 5 GSSAPI mechanism [RFC4121] is being used, + the HTTP server will be using a principal name of the form of + "HTTP/hostname". + +4.2. The Authorization Request Header + + Upon receipt of the response containing a "WWW-Authenticate" header + from the server, the client is expected to retry the HTTP request, + passing a HTTP "Authorization" header line. This is defined + according to the framework described in [RFC2616] and is utilized as + follows: + + credentials = "Negotiate" auth-data2 + auth-data2 = 1#( gssapi-data ) + + gssapi-data + + + + + +Jaganathan, et al. Informational [Page 3] + +RFC 4559 HTTP Authentication in Microsoft Windows June 2006 + + + This directive contains the base64 encoding of an + InitialContextToken, as defined in [RFC2743]. + + Any returned code other than a success 2xx code represents an + authentication error. If a 401 containing a "WWW-Authenticate" + header with "Negotiate" and gssapi-data is returned from the server, + it is a continuation of the authentication request. + + A client may initiate a connection to the server with an + "Authorization" header containing the initial token for the server. + This form will bypass the initial 401 error from the server when the + client knows that the server will accept the Negotiate HTTP + authentication type. + +5. Negotiate Operation Example + + The client requests an access-protected document from server via a + GET method request. The URI of the document is + "http://www.nowhere.org/dir/index.html". + + C: GET dir/index.html + + The first time the client requests the document, no Authorization + header is sent, so the server responds with + + S: HTTP/1.1 401 Unauthorized + S: WWW-Authenticate: Negotiate + + The client will obtain the user credentials using the SPNEGO GSSAPI + mechanism type to identify generate a GSSAPI message to be sent to + the server with a new request, including the following Authorization + header: + + C: GET dir/index.html + C: Authorization: Negotiate a87421000492aa874209af8bc028 + + The server will decode the gssapi-data and pass this to the SPNEGO + GSSAPI mechanism in the gss_accept_security_context function. If the + context is not complete, the server will respond with a 401 status + code with a WWW-Authenticate header containing the gssapi-data. + + S: HTTP/1.1 401 Unauthorized + S: WWW-Authenticate: Negotiate 749efa7b23409c20b92356 + + The client will decode the gssapi-data, pass this into + Gss_Init_security_context, and return the new gssapi-data to the + server. + + + + +Jaganathan, et al. Informational [Page 4] + +RFC 4559 HTTP Authentication in Microsoft Windows June 2006 + + + C: GET dir/index.html + C: Authorization: Negotiate 89a8742aa8729a8b028 + + This cycle can continue until the security context is complete. When + the return value from the gss_accept_security_context function + indicates that the security context is complete, it may supply final + authentication data to be returned to the client. If the server has + more gssapi data to send to the client to complete the context, it is + to be carried in a WWW-Authenticate header with the final response + containing the HTTP body. + + S: HTTP/1.1 200 Success + S: WWW-Authenticate: Negotiate ade0234568a4209af8bc0280289eca + + The client will decode the gssapi-data and supply it to + gss_init_security_context using the context for this server. If the + status is successful from the final gss_init_security_context, the + response can be used by the application. + +6. Security Considerations + + The SPNEGO HTTP authentication facility is only used to provide + authentication of a user to a server. It provides no facilities for + protecting the HTTP headers or data including the Authorization and + WWW-Authenticate headers that are used to implement this mechanism. + + Alternate mechanisms such as TLS can be used to provide + confidentiality. Hashes of the TLS certificates can be used as + channel bindings to secure the channel. In this case clients would + need to enforce that the channel binding information is valid. Note + that Kerb-TLS [RFC2712] could be used to provide both authentication + and confidentiality, but this requires a change to the TLS provider. + + This mechanism is not used for HTTP authentication to HTTP proxies. + + If an HTTP proxy is used between the client and server, it must take + care to not share authenticated connections between different + authenticated clients to the same server. If this is not honored, + then the server can easily lose track of security context + associations. A proxy that correctly honors client to server + authentication integrity will supply the "Proxy-support: Session- + Based-Authentication" HTTP header to the client in HTTP responses + from the proxy. The client MUST NOT utilize the SPNEGO HTTP + authentication mechanism through a proxy unless the proxy supplies + this header with the "401 Unauthorized" response from the server. + + + + + + +Jaganathan, et al. Informational [Page 5] + +RFC 4559 HTTP Authentication in Microsoft Windows June 2006 + + + When using the SPNEGO HTTP authentication facility with client- + supplied data such as PUT and POST, the authentication should be + complete between the client and server before sending the user data. + The return status from the gss_init_security_context will indicate + that the security context is complete. At this point, the data can + be sent to the server. + +7. Normative References + + [RFC2743] Linn, J., "Generic Security Service Application Program + Interface Version 2", 2, Update 1", 2743, January 2000. + + [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate + Requirement Levels", BCP 14, RFC 2119, March 1997. + + [RFC4178] Zhu, L., Leach, P., Jaganathan, K., and W. Ingersoll, "The + Simple and Protected GSS-API Generic Security Service + Application Program Interface (GSS-API) Negotiation + Mechanism", 4178, October 2005. + + [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., + Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext + Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. + + [RFC2617] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., + Leach, P., Luotonen, A., and L. Stewart, "HTTP + Authentication: Basic and Digest Access Authentication", + RFC 2617, June 1999. + + [RFC2712] Medvinsky, A. and M. Hur, "Addition of Kerberos Cipher + Suites to Transport Layer Security (TLS)", RFC 2712, + October 1999. + + [RFC4121] Zhu, L., Jaganathan, K., and S. Hartman, "The Kerberos + Version 5 Generic Security Service Application Program + Interface (GSS-API) Mechanism: Version 2", RFC 4121, July + 2005. + + + + + + + + + + + + + + +Jaganathan, et al. Informational [Page 6] + +RFC 4559 HTTP Authentication in Microsoft Windows June 2006 + + +Authors' Addresses + + Karthik Jaganathan + Microsoft Corporation + One Microsoft Way + Redmond, WA 98052 + US + + EMail: karthikj@microsoft.com + + + Larry Zhu + Microsoft Corporation + One Microsoft Way + Redmond, WA 98052 + US + + EMail: lzhu@microsoft.com + + + John Brezak + Microsoft Corporation + One Microsoft Way + Redmond, WA 98052 + US + + EMail: jbrezak@microsoft.com + + + + + + + + + + + + + + + + + + + + + + + + +Jaganathan, et al. Informational [Page 7] + +RFC 4559 HTTP Authentication in Microsoft Windows June 2006 + + +Full Copyright Statement + + Copyright (C) The Internet Society (2006). + + This document is subject to the rights, licenses and restrictions + contained in BCP 78 and at www.rfc-editor.org/copyright.html, and + except as set forth therein, the authors retain all their rights. + + 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. + +Intellectual Property + + 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. Information + on the procedures with respect to rights in RFC documents can be + found in BCP 78 and BCP 79. + + Copies of IPR disclosures made to the IETF Secretariat and any + assurances of licenses to be made available, or the result of an + attempt made to obtain a general license or permission for the use of + such proprietary rights by implementers or users of this + specification can be obtained from the IETF on-line IPR repository at + http://www.ietf.org/ipr. + + The IETF invites any interested party to bring to its attention any + copyrights, patents or patent applications, or other proprietary + rights that may cover technology that may be required to implement + this standard. Please address the information to the IETF at + ietf-ipr@ietf.org. + +Acknowledgement + + Funding for the RFC Editor function is provided by the IETF + Administrative Support Activity (IASA). + + + + + + + +Jaganathan, et al. Informational [Page 8] + |