URI Scheme for SNMP May 2004 Network Working Group D.Black Internet Draft EMC Corporation Document: draft-black-snmp-uri-05.txt K. McCloghrie Expires: November 2004 Cisco Systems J. Schoenwaelder International University Bremen May 2004 Uniform Resource Identifier (URI) Scheme for the Simple Network Management Protocol (SNMP) Status of this Memo This document is an Internet-Draft and is subject to all provisions of Section 10 of RFC 2026. 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/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. Abstract SNMP and the Internet-Standard Management Framework are widely used for management of communication devices, creating needs to specify SNMP access (including access to SNMP MIB object instances) from non-SNMP management environments. For example, when out-of-band IP management is used via a separate management interface (e.g., for a device that does not support in-band IP access) there is a need for a uniform way to indicate how to contact the device for management. URIs fit this need well, as they allow a single text string to indicate a management access communication endpoint for a wide variety of IP-based protocols. This document defines a URI scheme so that SNMP can be designated as the protocol used for management. The scheme also allows a URI to designate one or more MIB object instances. Black Expires - November 2004 [Page 1] URI Scheme for SNMP May 2004 Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC 2119]. Table of Contents 1. Introduction...................................................2 2. Syntax of an SNMP URI..........................................3 2.1 Relative URI Considerations................................4 3. Semantics and Operations.......................................4 3.1 SNMP Service URIs..........................................4 3.2 SNMP Object URIs...........................................5 3.3 OID Groups in SNMP URIs....................................8 3.4 Interoperability Considerations............................9 4. Examples.......................................................9 5. Security Considerations.......................................10 6. IANA Considerations...........................................11 7. Change History (to be deleted prior to RFC publication).......11 8. Normative References..........................................12 9. Informative References........................................13 10. Acknowledgments..............................................13 11. Author's Addresses...........................................14 1. Introduction SNMP and the Internet-Standard Management Framework were originally devised to manage IP devices via in-band means where management access is primarily via the same interface(s) used to send and receive IP traffic. SNMP's wide adoption has resulted in its use to manage communication devices that do not support in- band IP access (e.g., Fibre Channel devices); a separate out-of- band IP interface is often used for management. URIs provide a convenient way to locate that interface and specify the protocol to be used for management; one possible scenario is for an in-band query to return a URI that indicates how the device is managed. This document specifies a URI scheme to permit SNMP (including a specific SNMP context) to be designated as the management protocol by such a URI. This scheme also allows a URI to refer to specific object instances within an SNMP MIB. For a detailed overview of the documents that describe the current Internet-Standard Management Framework, please refer to section 7 of [RFC 3410]. Black Expires - November 2004 [Page 2] URI Scheme for SNMP May 2004 2. Syntax of an SNMP URI An SNMP URI has the following ABNF [RFC 2234] syntax: snmp_URI = "snmp:" "//" [ user "@" ] host [ ":" port ] [ "/" context [ ";" "engine=" engine ] [ "/" ( oid | oid-group ) [ "+" | ".*" ]]] user = < SNMP user name as specified by [RFC 3414] > host = < as specified by [rfc2396bis] > port = < as specified by [rfc2396bis] > engine = hex [ (hex)* ] ; SNMP contextEngineID as ; specified by [RFC 3411] hex = < Hex digit, as specified by [rfc2396bis] > context = < SNMP context name as specified by [RFC 3411] > oid-group = "(" oid [ ( "," oid )* ] ")" oid = < as specified by [RFC 3061] > The [ user "@" ] host [ ":" port ] portion of the above syntax matches the URI authority syntax specified in section 3 of [rfc2396bis] with the additional restriction that (when present) the user component (userinfo in [rfc2396bis]) MUST be an SNMP user name. If the user is empty or not given, the entity making use of an SNMP URI is expected to know what SNMP user name to use if one is required. If the port is empty or not given, port 161 is assumed. If the context is empty or not given, the zero-length string ("") is assumed, as it is the default SNMP context. An SNMP contextEngineID is a variable-format binary element that is usually discovered by an SNMP Manager. If the engine is empty or not given, the engine is to be discovered by interrogating the SNMP Agent at the specified host and port; see Section 3.1. An SNMP URI that designates the default SNMP context ("") MAY end with the "/" character that introduces the context component. An SNMP URI MUST NOT end with the "/" character that introduces the oid or oid-group component, as the empty string is not a valid oid for SNMP. The encoding rules specified in [rfc2396bis] apply to SNMP URIs, including the use of percent encoding ("%" character followed by two hex digits) to represent characters other than unreserved characters. SNMP allows any UTF-8 character to be used in a user name or context name; all multi-byte UTF-8 characters in an SNMP URI MUST be percent encoded as specified in Section 2.4 of [rfc2396bis]. SNMP URIs will generally be short enough to avoid implementation string length limits (e.g., that may occur at 255 characters). Black Expires - November 2004 [Page 3] URI Scheme for SNMP May 2004 Use of IP addresses in SNMP URIs is acceptable in situations where dependence on availability of DNS service is undesirable or must be avoided; otherwise IP addresses should not be used (see [RFC 1900] for further explanation). 2.1 Relative URI Considerations Use of the SNMP default context (zero-length string) within an SNMP URI can result in a second instance of "//" in the URI, e.g.: snmp://// This is allowed by [rfc2396bis]; if a URI parser does not handle the second "//" correctly, the parser is broken and needs to be fixed. This example is important because use of the SNMP default context in SNMP URIs is expected to be common. On the other hand, the second occurrence of "//" in an absolute SNMP URI affects usage of relative URIs because a "//" at the start of a relative URI always introduces an authority component. Specifically, a relative SNMP URI of the form // is not usable because the "//" causes to be parsed as an authority, resulting in a syntax error. To avoid this problem, relative SNMP URIs that start with "//" but do not contain an authority component MUST NOT be used. The intended functionality of such relative URIs can be achieved by prefixing a "." or "..", depending on the base URI (e.g., ..//). 3. Semantics and Operations An SNMP URI that does not include any oids is called an SNMP service URI because it designates a communication endpoint for access to SNMP management service. An SNMP URI that includes one or more oids is called an SNMP object URI because it designates one or more object instances in an SNMP MIB. 3.1 SNMP Service URIs An SNMP service URI does not designate a data object, but rather an SNMP context to be accessed by a service; the telnet URI scheme [RFC 1738] is another example of URIs that designate service access. The expected means of using an SNMP service URI is to employ an SNMP Manager to access the SNMP context designated by the URI via the SNMP Agent at the host and port designated by the URI; if the context is empty or not given in the URI, "" (the zero-length string) is assumed as it is the default SNMP context. If an engine is given in an SNMP service URI, the context is to be accessed via that SNMP engine. If the engine is empty or not Black Expires - November 2004 [Page 4] URI Scheme for SNMP May 2004 given in the URI, the engine is to be discovered; the engine to be used is the one that supports the context designated by the URI. The engine component of the URI SHOULD be present if more than one engine at the designated host and port supports the designated context. Many common uses of SNMP URIs are expected to omit (i.e., default) both the engine and the context because they do not involve accessing SNMP proxy agents, the most common reason for multiple SNMP engines to exist at a single host and port. Specifically, when an SNMP Agent is local to the network interface that it manages, the agent will usually have only one engine, in which case it is safe to omit the engine component of an SNMP URI. In addition, many SNMP Agents that are local to a network interface support only the default SNMP context (zero-length string). 3.2 SNMP Object URIs An SNMP object URI contains one or more oids. The URI is used by first separating the oid or oid group (including its preceding slash plus any parentheses and/or suffix), and then processing the resulting SNMP service URI as specified in Section 3.1 (above) to determine the SNMP context to be accessed. The engine component of the URI SHOULD be present if more than one engine at the designated host and port supports the designated context. The oid or oid group is then used to generate SNMP operations directed to that SNMP context. The semantics of an SNMP object URI depend on whether the oid or oid group has a suffix and what that suffix is. There are three possible suffix formats; in each case, the MIB object instances are designated within the SNMP context specified by the service URI portion of the SNMP object URI. The semantics of an SNMP object URI that contains a single oid are: (1) An oid without a suffix designates the MIB object instance named by the oid. (2) An oid with a "+" suffix designates the lexically next MIB object instance following the oid. (3) An oid with a ".*" suffix designates the set of MIB object instances for which the oid is a strict lexical prefix; this does not include the MIB object instance named by the oid. An oid group in an SNMP URI consists of a set of oids in parentheses. For cases (1) and (2), the oid group semantics are the extension of the single oid semantics to each oid in the group (e.g., in case (2) the URI designates the set of MIB object instances consisting of the lexically next object instance for each oid in the group). For case (3), the oid group semantics are Black Expires - November 2004 [Page 5] URI Scheme for SNMP May 2004 an iterated version of case (2) where the iteration ceases when any element of the group fails to yield a valid MIB object instance. When there is a choice among suffix formats to designate the same MIB object instance or instances, the above list is in order of preference (no suffix is most preferable) as it runs from most precise to least precise. This is because an oid without a suffix precisely designates an object instance, whereas a "+" suffix designates the next object instance, which may change, and the ".*" suffix could designate multiple object instances. Multiple syntactically distinct SNMP URIs SHOULD NOT be used to designate the same MIB object instance or set of instances as this may cause unexpected results in URI-based systems that use string comparison to test URIs for equality. Data access based on an SNMP URI returns an SNMP variable binding for each MIB object instance designated by the URI. An SNMP variable binding binds a variable name (oid) to a value or SNMP exception (see [RFC 3416]). The SNMP operation or operations generated to access data designated by an SNMP object URI depend on the oid or oid group suffix or absence thereof: (1) For an oid or oid group without a suffix, an SNMP Get operation is generated using each oid as a variable binding name. If an SNMP error occurs, that error is the result of URI data access. If any returned variable binding contains a "noSuchObject" exception or a "noSuchInstance" exception, all bindings are ignored and URI data access is successful but returns no data. Otherwise the returned variable bindings are the result of URI data access. (2) For an oid or oid group with a "+" suffix, an SNMP GetNext operation is generated using each oid as a variable binding name. If an SNMP error occurs, that error is the result of URI data access. If any returned variable binding contains an "endOfMibView" exception, all bindings are ignored and URI data access is successful but returns no data. Otherwise the returned variable bindings are the result of URI data access. (3) For an oid or oid group with a ".*" suffix, an SNMP GetNext operation is initially generated using each oid as a variable binding name. If the result is an SNMP error, that error is the result of URI data access. If any returned variable binding contains an oid for which the corresponding URI oid is not a lexical prefix or contains an "endOfMibView" exception, all bindings are ignored and the URI data access is successful but returns no data. Black Expires - November 2004 [Page 6] URI Scheme for SNMP May 2004 Otherwise the results of the GetNext operation are saved, and another SNMP GetNext operation is generated using the newly returned oids as variable binding names; this is iterated until a GetNext operation returns one of the following: a) an SNMP error b) a variable binding containing an oid for which the corresponding URI oid is not a lexical prefix c) a variable binding containing an "endOfMibView" exception The iteration ceases at this point, and the results of this final SNMP GetNext operation are ignored. The result of URI data access consists of the groups of variable bindings from the preceding successful SNMP GetNext operations. SNMP GetBulk operations MAY be used to optimize this iterated access. Any applicable SNMP operation, including GetBulk, MAY be used to access data for all or part of multiple SNMP URIs (e.g., via use of multiple variable bindings in a single operation). The use of relative object URIs that do not change context (i.e., ./oid) should be viewed as a hint that optimization is possible. This can be useful when independent iteration is desired on multiple oids in the same context, as use of two URIs (e.g., base and relative) with the ".*" suffix will cause both iterations to run to their respective ends. In contrast, when ".*" is applied to an oid group the iteration stops when any oid in the group can no longer be iterated. SNMP operations can bind oids to SNMP exceptions ("noSuchObject", "noSuchInstance", and "endOfMibView") that indicate no data is available for the requested binding. The design of SNMP URIs shields URI users from such exceptions for simplicity. The results of any successful SNMP operation that returns such an exception are ignored; that SNMP operation is considered to have succeeded and returned no data. This is analogous to successful HTTP access to an empty web page (e.g., an HTTP 204 No Content status code as opposed to a 404 Not Found status code for a page that does not exist [RFC 2616]). An SNMP URI can also be used to specify a MIB object instance or instances to be written; this causes generation of an SNMP Set operation instead of a Get. The "+" and ".*" suffixes MUST NOT be used in this case; any attempt to do so is an error and MUST NOT generate any SNMP Set operations. The values to be written to the MIB object instances are not specified within the SNMP URI. Black Expires - November 2004 [Page 7] URI Scheme for SNMP May 2004 3.3 OID Groups in SNMP URIs Parenthesized oid groups in SNMP URIs are intended to support MIB object instances for which access via a single SNMP operation is required to ensure consistent results. Therefore, the oids within an oid group in an SNMP URI SHOULD be accessed by a single SNMP operation with a variable binding corresponding to each oid in the group. A specific example involves the InetAddress and InetAddressType textual conventions defined in [RFC 3291]; the format of an InetAddress instance is specified by an associated InetAddressType instance. If two such associated instances are accessed via separate SNMP operations, the resulting values could be inconsistent (e.g., due to an intervening Set) causing the InetAddress value to be incorrectly interpreted. This single operation requirement ("SHOULD") also applies to each oid group resulting from iterated access for an SNMP URI that contains ".*". The data designated by a ".*" format SNMP URI is based on iterating until at least one iterated oid fails to return data designated by the URI (original oid is not a lexical prefix of the returned oid, or an SNMP exception is returned). This behavior differs from the corresponding behavior of the SNMP GetBulk operation which is only allowed to cease iterating early when no iterated oid returns useful data. When any of a GetBulk's iterated oids stop returning useful data, bindings to "endOfMibView" exceptions are returned for those oids until iteration reaches the point that no iterated oid returns useful data (or the GetBulk operation is complete). This approach is not applicable when an iterated oid from a ".*" format SNMP URI reaches the end of its lexical scope because the end of the MIB has not been reached, so using "endOfMibView" would be incorrect and risk misinterpretation by SNMP code. Rather than inventing a new SNMP exception solely for ".*" format SNMP URIs, SNMP exceptions are hidden from URI users for simplicity. Given this approach, if the iteration for a ".*" format SNMP URI were to continue after an iterated oid has hit the end of its lexical prefix match, the size of subsequent groups of variable bindings would be smaller than the number of oids in the URI. This is counter to a more important aspect of GetBulk, namely that iteration results in matched sets of variable bindings (e.g., if there are three oids to be iterated [repeated], a set of three variable bindings for each iteration is returned). In order to avoid returning smaller oid sets, the definition of a ".*" URI ceases iteration when any oid hits the end of its lexical prefix match or returns an SNMP exception. This ensures that the structure of the information designated by a URI matches the structure of the URI's oid group (e.g., if the URI's oid group Black Expires - November 2004 [Page 8] URI Scheme for SNMP May 2004 contains three oids, the designated information consists of groups with three MIB object instances in each group). Relative URIs using ".*" provide almost as compact a specification of the independent iteration behavior of GetBulk, and as indicated above, use of relative URIs within the same context should be regarded as a hint that optimizations such as the use of GetBulk are possible. 3.4 Interoperability Considerations This document defines a transport-independent "snmp:" scheme that is intended to accommodate SNMP transports other than UDP. UDP is the default transport for access to information specified by an SNMP URI for backwards compatibility with existing usage, but other transports MAY be used. If more than one transport can be used (e.g., SNMP over TCP [RFC 3430] in addition to SNMP over UDP) the information or SNMP service access designated by an SNMP URI SHOULD NOT depend on which transport is used (for SNMP over TCP, this is implied by Section 2 of [RFC 3430]). An SNMP URI designates use of SNMPv3 as specified by [RFC 3416], [RFC 3417] and related documents, but older versions of SNMP MAY be used for access designated by an SNMP URI in accordance with [RFC 3584] where usage of such older versions is unavoidable. SNMP versions (e.g., v3) have been omitted from the SNMP URI scheme for forwards compatibility with any possible future successor to SNMPv3. 4. Examples snmp://snmp.example.com This example designates the default SNMP context at the SNMP Agent at UDP port 161 of host snmp.example.com . snmp://tester5@snmp.example.com:8161 This example designates the default SNMP context at the SNMP Agent at UDP port 8161 of host snmp.example.com and indicates that the SNMP user name "tester5" is to be used to access that Agent. A possible reason for use of a non-standard port is testing of a new version of SNMP Agent code. snmp://snmp.example.com/bridge1 This example designates the "bridge1" SNMP context at snmp.example.com. Because the engine component of the URI is Black Expires - November 2004 [Page 9] URI Scheme for SNMP May 2004 omitted, there SHOULD be at most one SNMP context engine at snmp.example.com that supports the "bridge1" context. snmp://snmp.example.com/bridge1;engine=800002b804616263 This example designates the "bridge1" context at snmp.example.com via the SNMP contextEngineID 800002b804616263 (string representation of a hexadecimal value). This avoids ambiguity if any other context engine supports a "bridge1" context. The above two examples are based on the figure in Section 3.3 of [RFC 3411]. snmp://snmp.example.com//1.3.6.1.2.1.1.3.0 snmp://snmp.example.com//1.3.6.1.2.1.1.3+ snmp://snmp.example.com//1.3.6.1.2.1.1.3.* These three examples all designate the sysUpTime.0 object instance in the SNMPv2-MIB for the default SNMP context ("") at snmp.example.com as sysUpTime.0 is: a) designated directly by oid 1.3.6.1.2.1.1.3.0, b) the lexically next MIB object instance after the oid 1.3.6.1.2.1.1.3, and c) the only MIB object instance whose oid has 1.3.6.1.2.1.1.3 as a lexical prefix. These three examples are provided for illustrative purposes only, as multiple syntactically distinct URIs SHOULD NOT be used to designate the same MIB object instance in order to avoid unexpected results in URI-based systems that use string comparison to test URIs for equality. snmp://example.com/bridge1/1.3.6.1.2.1.2.2.1.8.* This example designates the ifOperStatus column of the IF-MIB in the bridge1 SNMP context at example.com. snmp://example.com//(1.3.6.1.2.1.2.2.1.7,1.3.6.1.2.1.2.2.1.8).* This example designates all (ifAdminStatus, ifOperStatus) pairs in the IF-MIB in the default SNMP context at example.com. 5. Security Considerations An intended use of this URI scheme is designation of the location of management access to communication devices. Such location information may be considered sensitive in some environments, making it important to control even read access and possibly even to encrypt the information when sending it over the network. All uses of this URI scheme should provide security mechanisms appropriate to the environments in which such uses are likely to be deployed. Black Expires - November 2004 [Page 10] URI Scheme for SNMP May 2004 There are management objects defined in SNMP MIBs whose MAX-ACCESS is read-write and/or read-create. Such objects may be considered sensitive or vulnerable in some network environments. The support for SNMP SET operations in a non-secure environment without proper protection can have a negative effect on network operations. The individual MIB module specifications, and especially their security considerations, should be consulted for further information. Some readable objects in some MIB modules (i.e., objects with a MAX-ACCESS other than not-accessible) may be considered sensitive or vulnerable in some network environments. It is thus important to control even GET access to these objects and possibly to even encrypt the values of these objects when sending them over the network via SNMP. The individual MIB module specifications, and especially their security considerations, should be consulted for further information. This consideration also applies to objects for which read operations have side effects. SNMP versions prior to SNMPv3 did not include adequate security. Even if the network itself is secure (for example via use of IPsec), there is no control over who on the secure network is allowed to access and GET/SET (read/change/create/delete) the objects in MIB modules. It is RECOMMENDED that implementers consider the security features as provided by the SNMPv3 framework (see [RFC 3410], section 8 for an overview), including full support for SNMPv3 cryptographic mechanisms (for authentication and privacy). This is of additional importance for MIB elements considered sensitive or vulnerable because GETs have side effects. Further, deployment of SNMP versions prior to SNMPv3 is NOT RECOMMENDED. Instead, it is RECOMMENDED to deploy SNMPv3 and to enable cryptographic security. It is then a customer/operator responsibility to ensure that the SNMP entity giving access to a MIB module instance is properly configured to give access to the objects only to those principals (users) that have legitimate rights to indeed GET or SET (change/create/delete) them. 6. IANA Considerations The IANA is asked to register the URL registration template found in Appendix A in accordance with [RFC 2717]. 7. Change History (to be deleted prior to RFC publication) -00: Initial version - user, host and port only. -01: Initial attempt to add engine, context, and oid, plus support for alternate (non-UDP) transports. Black Expires - November 2004 [Page 11] URI Scheme for SNMP May 2004 -02: Reworked engine, context, and oid syntax. Made URI scheme transport-independent. Added more examples. Significant text editing and rearrangement. -03: Update to reference rfc2396bis draft instead of RFC 2396. Context and engine syntax changed to comply with rfc2396bis authority component restrictions. Minor text editing. -04: Remove "0x" engine prefix. Add discussion of relative URI impacts of embedded //. Add oid groups to support MIB object instances that need to be accessed together. Always discard SNMP "no data" response exceptions. More edits. -05: Spell out acronyms in title. Correct wording to refer to SNMP exceptions. More editing. 8. Normative References [rfc2396bis] Uniform Resource Identifiers (URI): Generic Syntax. T. Berners-Lee, R. Fielding, L. Masinter. Internet-Draft draft-fielding-uri-rfc2396bis. Work in Progress. February 2004. [RFC 2119] Key words for use in RFCs to Indicate Requirement Levels. S. Bradner. RFC 2119, BCP 14. March 1997. [RFC 2234] Augmented BNF for Syntax Specifications: ABNF. D. Crocker, Ed., P. Overell. RFC 2234. November 1997. [RFC 3061] A URN Namespace of Object Identifiers. M. Mealling. February 2001. [RFC 3411] An Architecture for Describing Simple Network Management Protocol (SNMP) Management Frameworks. D. Harrington, R. Presuhn, B. Wijnen. December 2002. [RFC 3414] User-based Security Model (USM) for version 3 of the Simple Network Management Protocol (SNMPv3). U. Blumenthal, B. Wijnen. RFC 3414. December 2002. [RFC 3416] Version 2 of the Protocol Operations for the Simple Network Management Protocol (SNMP). R. Presuhn, Ed. RFC 3416. December 2002. [RFC 3417] Transport Mappings for the Simple Network Management Protocol (SNMP). R. Presuhn, Ed. RFC 3417. December 2002. [RFC 3584] Coexistence between Version 1, Version 2, and Version 3 of the Internet-standard Network Management Framework. R. Frye, D. Levi, S. Routhier, B. Wijnen. RFC 3584. August 2003. Black Expires - November 2004 [Page 12] URI Scheme for SNMP May 2004 9. Informative References [RFC 1738] Uniform Resource Locators (URL). T. Berners-Lee, L. Masinter, M. McCahill. RFC 1738. December 1994. [RFC 1900] Renumbering Needs Work. B. Carpenter, Y. Rekhter. RFC 1900. February 1996. [RFC 2026] The Internet Standards Process -- Revision 3. S. Bradner. RFC 2026, BCP 9. October 1996. [RFC 2616] Hypertext Transfer Protocol -- HTTP/1.1. R. Fielding, J. Gettys, J. Mogul, H. Frystyk, L. Masinter, P. Leach, T. Berners-Lee. RFC 2616. June 1999. [RFC 2717] Registration Procedures for URL Scheme Names. R. Petke, I. King. RFC 2717. November 1999. [RFC 3291] Textual Conventions for Internet Network Addresses. M. Daniele, B. Haberman, S. Routhier, J. Schoenwaelder. RFC 3291. May 2002. [RFC 3410] Introduction and Applicability Statements for Internet- Standard Management Framework. J. Case, R. Mundy, D. Partain, B. Stewart. RFC 3410. December 2002. [RFC 3430] Simple Network Management Protocol Over Transmission Control Protocol Transport Mapping. J. Schoenwaelder. December 2002. [RFC 3617] Uniform Resource Identifier (URI) Scheme and Applicability Statement for the Trivial File Transfer Protocol (TFTP). E. Lear. October 2003. 10. Acknowledgments Portions of this draft were adapted from Eliot Lear's TFTP URI scheme specification [RFC 3617]. The security considerations text was adapted from the widely used security considerations "boilerplate" for MIB modules. Comments from Ted Hardie, Michael Mealing, Larry Masinter, and the uri@w3c.org mailing list on earlier versions of this draft have resulted in significant improvements and are gratefully acknowledged. Black Expires - November 2004 [Page 13] URI Scheme for SNMP May 2004 11. Author's Addresses David L. Black EMC Corporation 176 South Street Hopkinton, MA 01748 Phone: +1 (508) 293-7953 Email: black_david@emc.com Keith McCloghrie Cisco Systems, Inc. 170 West Tasman Drive San Jose, CA USA 95134 Phone: +1 (408) 526-5260 Email: kzm@cisco.com Juergen Schoenwaelder International University Bremen P.O. Box 750 561 28725 Bremen Germany Phone: +49 421 200 3587 Email: j.schoenwaelder@iu-bremen.de Appendix A. Registration Template URL scheme name: snmp URL scheme syntax: Section 2 Character encoding considerations: Section 2 Intended usage: Section 1 Applications and/or protocols which use this scheme: SNMP, all versions, see [RFC 3410] and [RFC 3584]. Also SNMP over TCP, see [RFC 3430]. Interoperability considerations: Section 3.4 Security considerations: Section 5 Relevant publications: See [RFC 3410] for list. Also [RFC 3430] and [RFC 3584]. Contact: David L. Black, Section 11 Author/Change Controller: IESG Black Expires - November 2004 [Page 14]