Network Working Group
Internet DraftS. Suehring Document: draft-ietf-secsh-scp-sftp-ssh-uri- Sentry Insurance 01.txtInternet-Draft Expires: December 16, 2005 J. Salowey Cisco Systems Expires: April 2004 October 2003June 14, 2005 SCP/SFTP/SSH URI Format draft-ietf-secsh-scp-sftp-ssh-uri-01.txtdraft-ietf-secsh-scp-sftp-ssh-uri-02.txt Status of this Memo This documentBy submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is an Internet-Draftaware have been or will be disclosed, and is subject to all provisionsany of which he or she becomes aware will be disclosed, in accordance with Section 106 of RFC2026.BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.htmlhttp://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.htmlhttp://www.ietf.org/shadow.html. This Internet DraftInternet-Draft will expire on February 8, 2004.December 16, 2005. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved.(2005). Abstract This document describes the Uniform Resource Identifiers used to locate resources for the SCP, SFTP, and SSH protocols. The document describes the generic syntax involved in URI definitions as well as specific definitions for each protocol. These specific definitions may include user credentials such as username and password and also may include other parameters such as fingerprint. In addition, security considerations and examples are also provided within this document. SCP/SFTP/SSH URI Format October 2003Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. General Syntax.................................................2 1.1Syntax . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1 SSH URI....................................................2 1.2URI . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 SCP and SFTP URI...........................................2 2. Parameters.....................................................3 2.1URI . . . . . . . . . . . . . . . . . . . . . 3 3. Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1 SSH connection parameters..................................3 2.2parameters . . . . . . . . . . . . . . . . 4 3.2 SFTP Parameters............................................4 3. Examples.......................................................4Parameters . . . . . . . . . . . . . . . . . . . . . 5 4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations........................................4Considerations . . . . . . . . . . . . . . . . . . . 6 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6 6.1 Normative References..............................................5 Non-Normative References..........................................6 Author Information................................................6References . . . . . . . . . . . . . . . . . . . 6 6.2 Informative References . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 7 Intellectual Property and Copyright Statements . . . . . . . . 8 1. Introduction This document describes the Uniform Resource Identifiers (URIs) to be used with the SSH, SCP, and SFTP protocols. 2. General Syntax The URI for each protocol shall consist of the scheme and the scheme specific portion separated by a colon ":", as discussed in RFC 2396 .[RFC3986] This specification shall adopt the definitions "port", "host", "scheme", "userinfo", and "authority" from RFC 2396. 1.1[RFC3986]. 2.1 SSH URI The SSH scheme shall consist of the protocol acronym followed by a colon ":" and a double slash "//" in accordance with RFC 2718.[RFC2718]. The first component of the scheme specific portion MAY include credentials (userinfo) consisting of a username and optionally also including a password.password, separated by a colon ":". Including the password in the URLURI is NOT RECOMMENDED. The usernameRECOMMENDED and password componentsis deprecated in accordance with [RFC3986] One or more optional connection parameters (conn-parameters) may be specified within the userinfo section of the URI. These conn- parameters are separated from the credentials by a single colon ":".semi-colon ";" and from each other by a comma ",". Following the userinfo, if present, and the conn-parameters, if present the at-sign "@" shall precede the authority section of the URI. Optionally, the authority section MAY also include the port preceded by a colon ":". If the port is not included, the default port is assumed. Following the port additional parameters may be specified. These parameters are defined in the connection parameters section.ssh_URI = "ssh://" [ userinfo ] [ ";"conn-parameter=value ] [ "@" ] host [ ":" port ] [;conn-parameter=value] 1.22.2 SCP and SFTP URI For SCP and SFTP, the scheme portion (scp: or sftp:) is followed by a double slash "//". SCP/SFTP/SSH URI Format October 2003Both SCP and SFTP URLsURIs are terminated by a single slash "/" followed by the path information to the requested resource. The first component of the scheme specific portion MAY include credentials (userinfo) consisting of a username and optionally also including a password.password, separated by a colon ":". Including the password in the URLURI is NOT RECOMMENDED. The usernameRECOMMENDED and password componentsis deprecated in accordance with [RFC3986] One or more optional connection parameters (conn-parameters) may be specified within the userinfo section of the URI. These conn- parameters are separated from the credentials by a single colon ":".semi-colon ";" and from each other by a comma ",". Following the userinfo, if present, and the conn-parameters, if present the at-sign "@" shall precede the authority section of the URL.URI. Optionally, the authority section MAY also include the port preceded by a colon ":". If the port is not included, the default port is assumed. Following the port additional parameters may be specified. These parameters are defined in the connection parameters section.scp_URI = "scp://" [userinfo ] [ ";"conn-parameter=value ] [ userinfo"@" ] host [ ":" port ] [ ; parameter = value ] [ abs_path[abs_path ] Following the port additional parameters may be specified. These parameters are defined in the connection parameters section. Following the path additional sftp specific parameters may be specified. sftp_URI = "sftp://" [ userinfo ] [ ";"conn-parameter=value] [ "@" ] host [ ":" port ] [;conn-parameter=value][ abs_path ] [;sftp-parameter=value][ ";"sftp-parameter=value ] The URIs for SFTP and SCP are hierarcicalhierarchical URIs where each component of the abs_path consists of path elements separated by a '/'. This formatting is meant to represent the same formatpath information as usedin the FTP URL described in section 2.2.2Section 5 of . 2.[I-D.ietf-secsh-filexfer]. 3. Parameters 2.13.1 SSH connection parameters The following parameters are associated with an SSH connection and are applicable to SSH, SFTP and SCP. All parameters are optional and MUST NOT overwrite configured defaults. Individual parameters are separated by a comma (","). Additional parameters MAY be used. fingerprint The fingerprint parameter contains the fingerprint of the host key for the host specified in the URL. The fingerprint is encoded as host-key-alg:fingerprint.host-key-alg-fingerprint. Host-key-alg is host public key algorithm defined in [I-D.ietf-secsh-transport] and the fingerprint format is defined[I-D.ietf-secsh-publickeyfile]. For use in a URI, the fingerprint shall use a single dash "-" as a separator instead of the colon ":" as described in . SCP/SFTP/SSH URI Format October 2003[I-D.ietf-secsh- publickeyfile]. This parameter MUST NOT overwrite a key that is already configured for the host. The fingerprint MAY be used to validate the authenticity of the host key if the URL was obtained from an authenticated source with its integrity protected. If this parameter is not included then the validity of the host key is validated using another method. See Security Considerations section for additional considerations. There MUST be only one fingerprint parameter per host-key-alg for a given URL. 2.23.2 SFTP Parameters The SFTP parameters determine how to handle the file transfer character translation. Additional parameters MAY be used. newline The newline parameter determines how the server translates new line indicators. The possible choices are usually "\r" or "\n" or "\r\n". Thedefault is "\r\n".CRLF and implemented in accordance with Section 4.3 of [I-D.ietf-secsh-filexfer]. typecode The typecode identifies the type of file which determines how it will be treated. Possible values are "i" for binary files, "a" for text files, and "d" for directory listings. 3.4. Examples The following section shows basic examples of URLs for each protocol. This section should not be considered to include all possible combinations of URLs for each protocol. ssh://user@host ssh://user@host:2222 ssh://firstname.lastname@example.org;fingerprint=ssh-dss:c1:b1:30:29:d7:b8 :de:6c:97:77:10:d7:46:41:63:87 scp://user:password@host/file.txtssh://user;fingerprint=ssh-dss-c1-b1-30-29-d7-b8-de-6c-97- email@example.com scp://firstname.lastname@example.org/file.txt sftp://user@host/dir/path/file.txt sftp://email@example.com:2222;fingerprint=ssh-dss:c1:b1:30 :29:d7:b8:de:6c:97:77:10:d7:46:41:63:87, 4.sftp://user;newline=CR,fingerprint=ssh-dss-c1-b1-30-29-d7-b8-de -firstname.lastname@example.org:2222/ 5. Security Considerations SCP/SFTP/SSH URI Format October 2003In general, URIs themselves have no security considerations. However, since the password for each scheme can optionally be included within the URLURI it should be noted that doing so poses a security risk. Since URLsURIs are usually sent in the clear with no encryption or other security, any password or other credentials (userinfo) included could be seen by a potential attacker. Care must also be taken in handling fingerprints associated with URLsURIs because URLsURIs transmitted or stored without protection may be modified by an attacker. In general an implementation cannot determine the source of a URLURI so a fingerprint received in a URLURI should have no more trust associated with it than a raw public key received in the SSH protocol itself. If a locally configured key exists for the server already it MUST NOT be automatically overwritten with information from the URL.URI. If the host is unknown then the implementation should treat the fingerprint received with the same caution that it does with any unknown public key. The client MAY offer the fingerprint and URLURI for external validation before allowing a connection based on this information. If the client chooses to make a connection based on the URLURI information and it finds that the public key in the URLURI and the public key offered by the server do not match then it SHOULD provide a warning and provide a means to abort the connection. Sections 3.14.1 and 188.8.131.52.4 of [I-D.ietf-secsh- architecture] provide a good discussion of handling public keys received in the SSH protocol. 6. References 6.1 Normative References  Berners-Lee, T., Fielding, R., Masinter, L., "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396, August 1998.  Markus Friedl, "SSH Fingerprint Format", http://www.ietf.org/internet-drafts/draft-ietf-secsh-fingerprint- 01.txt, work in progress [I-D.ietf-secsh-architecture] Ylonen, T.,T. and C. Lonvick, "SSH Protocol Architecture", http://www.ietf.org/internet-drafts/draft-ietf-secsh-architecture- 14.txt, workdraft-ietf-secsh-architecture-22 (work in progreess  Ylonen, T.,progress), March 2005. [I-D.ietf-secsh-filexfer] Galbraith, J., "SSH File Transfer Protocol", draft-ietf-secsh-filexfer-09 (work in progress), June 2005. [I-D.ietf-secsh-publickeyfile] Galbraith, J. and R. Thayer, "SSH Public Key File Format", draft-ietf-secsh-publickeyfile-08 (work in progress), April 2005. [I-D.ietf-secsh-transport] Lonvick, C., "SSH Transport Layer Protocol", http://www.ietf.org/internet-drafts/draft-ietf-secsh-transport- 16.txt, work in progress  Hoffman, P., Definitions of Early URI Schemes", http://www.ietf.org/internet-drafts/draft-hoffman-rfc1738bis-00.txt, workdraft-ietf-secsh-transport-24 (work in progress SCP/SFTP/SSH URI Format October 2003 Non-Normative Referencesprogress), March 2005. [RFC2718] Masinter, L., et. al.,Alvestrand, H., Zigmond, D., and R. Petke, "Guidelines for new URL Schemes", RFC 2718, November 1999. [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, January 2005. 6.2 Informative References [RFC3305] Mealling, M.,M. and R. Denenberg, R.,"Report from the Joint W3C/IETFW3C/ IETF URI Planning Interest Group: Uniform Resource Identifiers (URIs), URLs, and Uniform Resource Names (URNs): Clarifications and Recommendations", RFC 3305, August 2002. Author InformationAuthors' Addresses Steve Suehring Sentry Insurance 1800 North Point Dr, G2/61-17PO BOX 1033 Stevens Point, WI 54481 US Email: email@example.com Joseph Salowey Cisco Systems 2901 Third Avenue3rd Ave Seattle, WA 98121 E-mail:US Email: firstname.lastname@example.org Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual propertyIntellectual 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; neithernor does it represent that it has made any independent effort to identify any such rights. Information on the IETF'sprocedures with respect to rights in standards-track and standards-related documentationRFC documents can be found in BCP-11.BCP 78 and BCP 79. 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