Network Working Group Bernard Aboba INTERNET-DRAFT Microsoft Category: Experimental <draft-aboba-radius-03.txt> 2 February 1999 Lightweight Directory Access Protocol (v3): Schema for the Remote Access Dialin User Service (RADIUS) 1. Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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." To view the list Internet-Draft Shadow Directories, see http://www.ietf.org/shadow.html. The distribution of this memo is unlimited. It is filed as <draft- aboba-radius-03.txt>, and expires August 1, 1999. Please send comments to the authors. 2. Copyright Notice Copyright (C) The Internet Society (1999). All Rights Reserved. 3. Abstract This document defines a schema for the Remote Access Dialin User Service (RADIUS). This schema makes it possible to integrate a RADIUS server with an LDAP-based directory service, making it possible for an organization to maintain a single store of user information. This consolidation is desirable since it results in a reduction in the administrative workload, and eliminates the need to synchronize across multiple user information stores. Aboba Experimental [Page 1]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 4. Introduction Today enterprises are looking to simplify the process of user administration by replacing application-specific directories with a unified directory service based on LDAP v3, described in [5]-[6]. Operating multiple stores of user information is unappealing, since this may require rekeying of information or sychronization between multiple stores, resulting in increased administrative costs. Maintaining multiple stores also raises concerns about inconsistency and replication delays. With the advent of enterprise resource planning (ERP) and personnel management systems, information on a user is typically entered at the time of hiring, and is retained until termination. If an LDAP-based directory is also deployed, this necessitates synchronization with the of the personnel database in order to maintain consistency. Should the enterprise then deploy NAS devices or layer 2 tunneling solutions, there may be a need to add a RADIUS server or if extended security is required, a backend security server. Each of these may require their own user information store. In order to avoid these problems, it is desirable to consolidate stores of user information. One way this can be achieved is to make it possible for RADIUS servers and security add-ons to store their user information in an LDAP-based directory. This document defines an LDAP schema for the Remote Access Dialin User Service (RADIUS). The RADIUS protocol, described in [1]-[4], supports authentication, authorization and accounting for dialup users. To date, RADIUS servers have stored user data in a variety of ways, including databases and flat files. A goal of this schema is to make it possible to add support for LDAP-based directory services to existing RADIUS server implementations. In order to permit this schema to be used with a wide range of directory service implementations, it is necessary to avoid reliance on features that have not been widely implemented, such as multiple inheritance. 4.1. Administrative model The schema defined in this document includes user object attributes, as well as profile and policy objects. User object attributes are used in situations where it may be desirable to override behavior supplied in a profile, or where it is desired that individual users be given an unique value for an attribute. For example, where static addresses are assigned, each user will typically have a different IP address. Similarly, where callback is used, callbackNumber will typically differ between users. Aboba Experimental [Page 2]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 However, it is not desirable to depend exclusively on user object attributes. Since it is likely that groups of users will tend to have the same parameter values, an implementation based solely on user-object attributes results in unnecessary replication, and also makes it difficult to change attributes for all members of a group. To reduce the replication problem, enable more effective caching, and ease the administrative burden, profile objects are required. Profiles support definition of parameter sets which apply to a group of users in a particular situation. Since it is expected that profiles will apply to large group of users, they can be effectively cached. Network administrators typically manage the authorization process via group assignments, and therefore will typically desire to fit profiles within the existing administrative model. In particular, it is highly desirable to allow an administrator to change the profile values applying to a group without having to edit the user objects for each member of the group. Within this schema, the mapping from profiles to groups is achieved via policy objects which contain the conditions that must be satisfied for a profile to be assigned, as well as a pointer to that profile. Group membership may be included among the conditions evaluated in assignment of a profile. Thus, profile/group binding can be expressed as a condition (group membership) resulting in assignment of a profile (the profile for that group). It should be noted that policy objects are not the only way to bind profiles to groups, nor are they necessarily the most efficient. For example, it is also possible to handle profile/group binding via a table, or even by encoding policy restrictions on a user certificate. The later may prove popular in the long term, given that today many firms already encode privileges relating to time of day and organizational function on employee badges. 4.2. Objects and attributes The RADIUS schema defined in this document requires support for several new classes: radiusProfileClass, radiusPolicyClass, radiusDictionaryClass, and eapDictionaryClass. The radiusProfileClass is used to store RADIUS attributes relevant to groups of users. The radiusPolicyClass is used to describe conditions under which a given profile may be applied. The radiusDictionaryClass is used to store the RADIUS Dictionary. This provides extensibility and allows RADIUS profile objects to be self describing. The eapDictionaryClass is used to store a mapping EAP types to user friendly names. EAP is described in [7]. Aboba Experimental [Page 3]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 The attributes in radiusProfileClass fall into two categories: attributes present in the Access-Reply, and attributes representing access constraints. An access constraint is a set of conditions that must be satisfied in order for access to be granted. These are expressed in the form of matching rules involving attributes present in the Access-Reply, as well as other attributes such as the time of day. For example, a matching rule involving the calledStationId and time of day can be created in order to limit access to those calling a given phone number during specified hours. Attributes present in the Access-Reply are stored in the directory so that the RADIUS server can retrieve them and include them in the Access- Reply. Access constraints are stored in the directory so that the RADIUS server can test the incoming Access-Request to determine whether to proceed with authentication, or immediately send an Access-Reject. Note that only static attributes present in Access-Reply need be stored in the directory; attributes which are computed on the fly can be recreated as needed. The attributes in radiusPolicyClass represent conditions which must hold for the profile indicated in radiusProfilePointer to be applied. As with access constraints, these conditions may involve matching rules applied to attributes in the Access-Request, as well as conditions involving time of day, Nas-Port-Type, or group memberships. For example, it may be desirable to give users different Session-Time or Port-Limit attributes depending on the time of day, or group memberships. This can be accomplished by creating policy expressions and profiles for each time of day/group membership combination. Similarly, it may be desirable to require that analog and ISDN callers do callback or call from a particular callingStationId, while this may not make sense for users connecting over a virtual private network (VPN). This can be accomplished by creating a policy expression that returns different profiles, depending on nasPortType. 4.2.1. User object attributes This schema proposes addition of attributes to the user object. As noted earlier, to enhance scalability, it is recommended that user object attributes only be used in cases where profile overide is necessary, or assignment of per-user attributes is required. Overide can in principle be required for any attribute that may be included in the Access-Reply, and so these attributes are among those that are added to the user object. Examples of attributes that may be assigned on a per-user basis include radiusFramedIPAddress, radiusCallbackNumber and radiusFramedRoute. Aboba Experimental [Page 4]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 Since many RADIUS parameters are expected to be identical for a group of users, typically the user object will contain a small set of Radius attributes. No user object attributes may be present if profiles are being applied conditionally and no per-user values are required. If it desired that a profile be unconditionally executed, then this can be achieved either by creating a policy object with a radiusProfilePointer attribute but no npConstraint attribute, or by adding radiusPolicyPointer (a distinguished name pointing to a RADIUS Profile Object) as a user object attribute. 4.2.2. Profiles Profile attributes fall into two major categories. One category of attributes are static attributes that may be returned in an Access- Reply. These attributes use a prefix of 'radius' and are included within the profile so that the RADIUS server may copy the values into the Access-Reply. Another category of attributes are those which represent conditions that must be satisfied for an Access-Accept to be sent. These attributes use a prefix of 'np', which stands for Network Policy. These attributes include npIPPoolName, npSessionsAllowed, npEAPType, npConstraint, and npAuthenticationType. npSessionsAllowed is used to limit the number of simultaneous sessions; npAuthenticationType indicates the acceptable authentication types (PAP, CHAP, MS-CHAP, EAP); npEAPType indicates the EAP-Type to be used to authenticate the user if EAP is negotiated as an authentication type; npIPPoolName indicates the name of the IP address pool that should be used in assigning the user's IP address. npConstraint is a string attribute used to express constraints based on time of day, or attributes present in the Access-Request, such as NAS- Port-Type or NAS-Identifier. Within this document, we allow profiles to include pointers to other profiles, so that profiles may form a linked list. This allows a hierarchy of profiles to be provided. More specific attributes overide more general ones. 4.2.3. Example All BIGCO employees are required to use token card authentication, and thus in the company profile the radiusAuthenticationType attribute is set to only allow EAP, and the radiusEAPType attribute is set for BIGCO's token card type. BIGCO also sets up a marketing profile providing a radiusSessionTimeout value of 30 minutes, a radiusPortLimit of one, and radiusFramedIpAddress set to indicate dynamic address Aboba Experimental [Page 5]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 allocation. However, Fred requires a static IP address, and thus his user object will contain a radiusFramedIpAddress attribute. Since BIGCO profiles are unconditionally applied, a policy object with a condition of (group == marketing) is used to assign a profile to marketing personnel. Another policy object of lower priority is used with no npConstraint attribute in order to assign a default profile. 4.3. Policy support The schema described in this document provides for the conditional application of a profile to a user via policy objects. Policy objects make it possible to have profile A apply to a user in one set of circumstances, and profile B apply in another set of circumstances. They also enable binding of profiles to groups. Each policy object corresponds to an IF/THEN statement; multiple policy objects may be required to express complex policies. Attributes in the policy object include npConstraint, a string attribute which expresses the conditions under which a profile will be applied; npSequence, an integer attribute which describes the order in which the policy object will be evaluated; and radiusProfilePointer, a Distinguished Name pointing to the RADIUS profile that will be applied if the conditions hold. The matching rule stored in npConstraint is an expression which may reference other attribute values and include pattern matching and other operations, such as equality tests. Policy objects without an npConstraint attribute can be used to indicate unconditional execution of a profile. Although a simple Policy Object is presented in this schema, more complex versions are possible. For example, a wider variety of operators and pattern matches might be supported within npConstraint. 4.3.1. Example Let us assume that BIGCO wishes to offer dialin access to their domestic sales force, as well as VPN access to contractors and to individuals from the finance group travelling overseas. In order to consistently manage and account for the use of their NAS devices and Layer 2 tunnel servers (PPTP/L2F/L2TP), BIGCO has chosen to adopt the RADIUS protocol. However, given the large number of employees and contractors that need to be managed, BIGCO desires a RADIUS solution integrated with their existing LDAP-based directory service and group structure. This will allow the network administrator to edit the user's RADIUS attributes with the same user-interface as they use to edit other user attributes, profiles, and policies, and will eliminate the need to maintain multiple Aboba Experimental [Page 6]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 stores of user information. As part of this service offering, BIGCO may wish to implement a number of policies. For example, in order to make sure that high speed dialin access is available to the sales force when they need it, BIGCO may wish to restrict use of the ISDN ports to sales personnel only during the hours of 9 AM - 5 PM, and permit the use of multilink. Since contractors are only to be given access to selected subnets, BIGCO may wish to apply a filter to their traffic. Since individuals in the finance group often access highly confidential information over the VPN, BIGCO may wish to require that these users authenticate via a smartcard, and use only 128-bit encryption so as to provide for extended security. For security reasons, BIGCO may wish to restrict contractors and finance users to a single login at a time. In certain cases, BIGCO may also wish to implement policies that depend on the type of port that the user is connecting to. For example, if the user is connecting via dialup, then it may be appropriate to include tunnel attributes within the Access-Accept, so as to set up a tunnel for the user. However, if the user is already connected via a tunnel, this would not be necessary. Similarly, if BIGCO only has a limited number of ISDN ports available, it may be desirable to set a shorter Session- Timeout or Idle-Timeout on these ports, or to set Port-Limit to one so as to not allow multi-link. The schema defined in this document permits enforcement of these and many other policies. 4.4. Caching The schema presented in this document will benefit from caching, since it is expected that profiles and policies will apply to large numbers of users. The first time the RADIUS server encounters a pointer to a given profile or policy, the profile or policy will be retrieved from the directory and cached. Subsequently, the profile or policy may be retrieved from the cache, speeding the retrieval process. As a result, it is to be expected that caching should result in a substantial performance gain. 5. Consistency and transaction issues While LDAP v3, described in [5], permits a list of modifications to a single object to be made as a single atomic operation, it does not support transacted modifications to multiple objects. In SNMP this functionality is supported through a "conceptual two-phase commit" applied to SET operations, as well as constructs such as the TextAndIncr textual convention, defined in [10]. In addition, within a globally replicated directory system, it is likely that directory replicas will Aboba Experimental [Page 7]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 be partially out of synchronization at any given time. This means that in any given replica it is possible for related objects to be in an inconsistent state. As a result, in order to ensure correctness, it is necessary to implement mechanisms for detecting and handling directory inconsistencies. This schema includes related objects which need to be consistently maintained. For example, policy objects contain an 'IF' (conditions) as well as a 'THEN' (a pointer to a profile object). In addition, it is possible for this schema to store data which relates to two ends of a link. For example, the Framed-Route and Framed-Routing attributes may be used to set up a routed dialup or VPN connection. In either of these two examples, if mechanisms are not provided to guarantee consistency of related objects, then inconsistent policies can be propagated. This is particularly dangerous with respect to link policies, since propagation of inconsistent policies could result in the links going down. This in turn could stop directory replication from proceeding, preventing resolution of the inconsistency. The network would thus remain in a deadlocked state requiring manual intervention. Directory-induced network lockup can be prevented through careful implementation. For example, policy objects and profiles may be maintained within the same containment hierarchy, edited within a temporary work area, and then propagated to the final location with a "transacted move." Consistency between related objects may be maintained through use of a version attribute. When retrieving a set of related objects, the version number can be checked to make sure that it is consistent within the set. If an entire set of objects cannot be obtained with the latest version number, then it may be necessary to revert to use of a previous consistent set of objects at an earlier version. Note that support for reversion implies that storage of related objects is archival; that is, addition of a new set of objects does not overwrite the previous version. Since support for object versioning is a generally useful capability, it makes the most sense to support this in a general way rather than doing it in a schema-specific manner. As a result, we have chosen not to add a version number attribute to the objects described in this document. A general mechanism for supporting versioning will be the subject of a future document. Aboba Experimental [Page 8]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 5.1. Extensibility Today vendors distinguish their RADIUS servers by a variety of means, including the range of supported attributes (standard and vendor- specific), and the breadth of policies that may be represented. As a result, while it is desirable to provide a common base set of classes and attributes which all RADIUS schemas will share, RADIUS server capabilities differ substantially from implementation to implementation, and a successful RADIUS schema definition must support this differentiation. The schema described in this document provides support for most of the attributes defined in [1]-[4], as well as including support for the RADIUS Dictionary and vendor-specific attributes, as well as conditional application of profiles. Within this framework, vendor differentiation can be achieved via two methods: adding attributes to the base RADIUS profile and policy classes, or creating subclasses inheriting from the base classes. Adding attributes to the base class is recommended in cases where the new attributes to be added do not conflict with those described in this document or in [1]-[4]. Where conflicts do not arise, new attributes, including vendor-specific attributes, may be added to the RADIUS dictionary, which allows RADIUS Profile objects to be self-describing. The goal is to allow attributes to be added without having to require an update to the RADIUS server code. Note however that a conventional RADIUS dictionary is only designed to describe attributes that are sent on the wire, while the RADIUS Dictionary object defined in this schema may also be used to define additional non-wire attributes (such as radiusAuthenticationType). This provides an additional element of flexibility, allowing new attributes to be defined and used within existing policy objects, without code changes. Creating a sub-class is desirable in cases where conflicts are possible. Such conflicts can arise for example, when vendors have defined attributes which conflict with the standard RADIUS attribute space described in [1]-[4]. In this case, the radiusVendorId attribute should included and set to the SMI Vendor Code, indicating that the profile is specific to a given vendor, and contains potentially conflicting elements. Since a RADIUS server searching for a profile with objectclass=radiusProfileClass will encounter both base class profiles and subclasses, the radiusVendorId attribute is critical in allowing an implementation to differentiate the profiles it can understand from those that it cannot. Typically an implementation will only wish to work with profiles whose radiusVendorId is either not present, zero (IETF RADIUS) or set to their own SMI Vendor Code. As with addition of attributes to the base class, when attributes are added to a subclass, the RADIUS Dictionary class should modified to allow the subclass to be Aboba Experimental [Page 9]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 self-describing. Since it is conceivable that RADIUS servers from two vendors may be deployed simultaneously, both desiring to store objects in the same LDAP-based directory service, and each implementing their own profile subclass, a method must be provided to allow a user to have more than one set of RADIUS profile and policy objects. This can be achieved by allowing the radiusProfilePointer to point to a container object rather than pointing to an object itself. The RADIUS server would then search the container for a RADIUS profile or policy with an appropriate radiusVendorId. In order to prevent name conflicts, it is recommended that vendors adding their own attributes prepend a suffix to all attribute names, so as to avoid name conflicts. Rather than redefining existing attributes, vendor should create their own attributes using suffixes in order to avoid conflict. To illustrate how extensibility features may be used, the additional attributes supported by a hypothetical BIGCO Profile Class are included. 6. User object additions The RADIUS schema proposes addition of the following attributes to the user object: MAY ( radiusServiceType $ radiusFramedProtocol $ radiusFramedIPAddress $ radiusFramedIPNetmask $ radiusFramedRoute $ radiusFramedRouting $ radiusFilterId $ radiusFramedMTU $ radiusFramedCompression $ radiusLoginIPHost $ radiusLoginService $ radiusLoginTCPPort $ radiusCallbackNumber $ radiusCallbackId $ radiusFramedRoute $ radiusFramedIPXNetwork $ radiusClass $ radiusVSA $ radiusSessionTimeout $ radiusIdleTimeout $ radiusTerminationAction $ radiusCalledStationId $ radiusCallingStationId $ radiusLoginLATService $ radiusLoginLATNode $ radiusLoginLATGroup $ radiusFramedAppleTalkLink $ radiusFramedAppleTalkNetwork $ radiusFramedAppleTalkZone $ radiusPortLimit $ radiusLoginLATPort $ radiusTunnelType $ radiusTunnelMediumType $ radiusTunnelServerEndpoint $ radiusTunnelPrivateGroupId $ radiusTunnelAssignmentId $ radiusTunnelClientEndpoint $ radiusTunnelPreference $ radiusTunnelPassword $ radiusArapFeatures $ Aboba Experimental [Page 10]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 radiusArapZoneAccess $ radiusArapSecurity $ radiusPasswordRetry $ radiusPrompt $ npSessionsAllowed $ npAuthenticationType $ npEAPType $ npConstraint $ npIPPoolName $ radiusProfilePointer $ radiusVendorId ) 7. Object definitions The RADIUS schema includes definition of the following objects: RADIUS Profile Class RADIUS Policy Class RADIUS Dictionary Class EAP Dictionary Class 7.1. RADIUS Profile Class ( radiusProfileClass 1 NAME 'radiusProfile' SUP profile PARENT (country $ organization $ organizationalUnit $ locality $ container) STRUCTURAL MUST ( cn ) MAY ( radiusServiceType $ radiusFramedProtocol $ radiusFramedIPAddress $ radiusFramedIPNetmask $ radiusFramedRoute $ radiusFramedRouting $ radiusFilterId $ radiusFramedMTU $ radiusFramedCompression $ radiusLoginIPHost $ radiusLoginService $ radiusLoginTCPPort $ radiusCallbackNumber $ radiusCallbackId $ radiusFramedRoute $ radiusFramedIPXNetwork $ radiusClass $ radiusVSA $ radiusSessionTimeout $ radiusIdleTimeout $ radiusTerminationAction $ radiusCalledStationId $ radiusCallingStationId $ radiusLoginLATService $ radiusLoginLATNode $ radiusLoginLATGroup $ radiusFramedAppleTalkLink $ radiusFramedAppleTalkNetwork $ radiusFramedAppleTalkZone $ radiusPortLimit $ radiusLoginLATPort $ radiusTunnelType $ radiusTunnelMediumType $ radiusTunnelServerEndpoint $ radiusTunnelPrivateGroupId $ radiusTunnelAssignmentId $ Aboba Experimental [Page 11]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 radiusTunnelClientEndpoint $ radiusTunnelPreference $ radiusTunnelPassword $ radiusArapFeatures $ radiusArapZoneAccess $ radiusArapSecurity $ radiusPasswordRetry $ radiusPrompt $ npSessionsAllowed $ npAuthenticationType $ npEAPType $ npConstraint $ npIPPoolName $ radiusProfilePointer $ radiusVendorId $ radiusDictionaryPointer ) ) 7.2. RADIUS Policy Class ( radiusPolicyClass 1 NAME 'radiusPolicy' SUP policy PARENT (country $ organization $ organizationalUnit $ locality $ container) STRUCTURAL MUST ( cn $ radiusProfilePointer ) MAY ( npConstraint $ npSequence ) ) 7.3. RADIUS Dictionary Class ( radiusDictionaryClass 1 NAME 'radiusDictionaryClass' SUP top PARENT (country $ organization $ organizationalUnit $ locality $ container) STRUCTURAL MUST ( cn $ radiusDictionaryEntry ) ) Aboba Experimental [Page 12]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 7.4. EAP Dictionary Class ( eapDictionaryClass 1 NAME 'eapDictionaryClass' SUP top PARENT (country $ organization $ organizationalUnit $ locality $ container) STRUCTURAL MUST ( cn $ eapDictionaryEntry ) ) 7.5. BIGCO Profile Class As described earlier, the base classes may be extended by attribute addition, subclassing, or both. An example of the subclassing approach is illustrated below. Here the bigcoProfileClass is created as a subclass of the radiusProfileClass and adds several attributes, each of which uses bigco as a suffix to avoid name collisions. ( bigcoProfileClass 1 NAME 'bigcoProfile' SUP radiusProfileClass PARENT (country $ organization $ organizationalUnit $ locality $ container) STRUCTURAL MUST ( ) MAY ( bigcoBapRequired $ bigcoBapLinednLimit $ bigcoBapLinednTime $ bigcoDynDirServer ) ) 8. Attribute definitions 8.1. New Attribute Types Used in the user object and RADIUS Profile Class ( radius radiusProfileClass 6 NAME 'radiusServiceType' DESC 'The service to be provided to the user. Values include: Login(1), Framed(2), Aboba Experimental [Page 13]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 Callback Login(3), Callback Framed(4), Outbound(5), Administrative(6), NAS Prompt(7), Authenticate Only(8), Callback NAS Prompt(9)' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 7 NAME 'radiusFramedProtocol' DESC 'For Framed service, the protocol to be provided to the user. Values include PPP(1), SLIP(2), ARAP(3), Gandalf(4), Xylogics(5)' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 8 NAME 'radiusFramedIPAddress' DESC 'IP address to be assigned to the user in dotted decimal notation' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 9 NAME 'radiusFramedIPNetmask' DESC 'Netmask to apply to the user in dotted decimal notation' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 10 NAME 'radiusFramedRouting' DESC 'Routing method for the user. Values include None(1), Send(2), Listen(3), Send & Listen(4)' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 11 Aboba Experimental [Page 14]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 NAME 'radiusFilterId' DESC 'String representing the filter list for the user' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' ) ( radius radiusProfileClass 12 NAME 'radiusFramedMTU' DESC 'Maximum Transmission Unit for the user' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 13 NAME 'radiusFramedCompression' DESC 'Compression protocol to be used on the link. Values include: None(1), VJ compression(2), IPX header compression(3)' EQUALITY integerMatch SYNTAX 'INTEGER' ) ( radius radiusProfileClass 14 NAME 'radiusLoginIPHost' DESC 'System with which to connect the user in dotted decimal notation' EQUALITY integerMatch SYNTAX 'INTEGER' ) ( radius radiusProfileClass 15 NAME 'radiusLoginService' DESC 'Service to be used to connect the user to the login host. Values include Telnet(1), Rlogin(2), TCP Clear(3), PortMaster(4), and LAT(5)' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 16 NAME 'radiusLoginTCPPort' DESC 'The TCP port with which the useris to be connected' EQUALITY integerMatch Aboba Experimental [Page 15]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 19 NAME 'radiusCallbackNumber' DESC 'Number to be called' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' SINGLE-VALUE ) ( radius radiusProfileClass 20 NAME 'radiusCallbackId' DESC 'Name of place to be called' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' SINGLE-VALUE ) ( radius radiusProfileClass 22 NAME 'radiusFramedRoute' DESC 'Routes to be plumbed for the user' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' ) ( radius radiusProfileClass 23 NAME 'radiusFramedIPXNetwork' DESC 'IPX Network number to be configured for the user' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 24 NAME 'radiusClass' DESC 'Class attribute for the user' SYNTAX 'OCTETSTRING' ) ( radius radiusProfileClass 25 NAME 'radiusVSA' DESC 'Vendor Specific Attribute for the user' SYNTAX 'OCTETSTRING' ) Aboba Experimental [Page 16]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 ( radius radiusProfileClass 27 NAME 'radiusSessionTimeout' DESC 'Per-session time limit in seconds. After this expires, the action specified in Termination-Action is taken' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 28 NAME 'radiusIdleTimeout' DESC 'The maximum number of consecutive seconds of idle connection allowed before session termination' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 29 NAME 'radiusTerminationAction' DESC 'Action taken when specified service is completed. Values include Default(1) or RADIUS-Request(2)' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 34 NAME 'radiusLoginLATService' DESC 'Identity of the LAT service to use' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' SINGLE-VALUE ) ( radius radiusProfileClass 35 NAME 'radiusLoginLATNode' DESC 'The node with which the user is to be automatically connected by LAT' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' SINGLE-VALUE ) ( radius radiusProfileClass 36 Aboba Experimental [Page 17]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 NAME 'radiusLoginLATGroup' DESC 'The LAT group codes which this user is authorized to use' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' SINGLE-VALUE ) ( radius radiusProfileClass 37 NAME 'radiusFramedAppleTalkLink' DESC 'The AppleTalk network number which should be used for the user' EQUALITY caseIgnoreIA5Match SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 38 NAME 'radiusFramedAppleTalkNetwork' DESC 'The AppleTalk network number which the NAS should probe to allocate an AppleTalk node for the user' EQUALITY caseIgnoreIA5Match SYNTAX 'INTEGER' ) ( radius radiusProfileClass 39 NAME 'radiusFramedAppleTalkZone' DESC 'The name of the Default AppleTalk Zone' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' SINGLE-VALUE ) ( radius radiusProfileClass 62 NAME 'radiusPortLimit' DESC 'Maximum number of ports to be provided' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 39 NAME 'radiusLoginLATPort' DESC 'The Port with which the user is to connected by LAT' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' Aboba Experimental [Page 18]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 SINGLE-VALUE ) ( radius radiusProfileClass 64 NAME 'radiusTunnelType' DESC 'String representing the type of tunnel to be set up, of the form Tag: Value. Values include PPTP(1), L2F(2), L2TP(3), ATMP(4), VTP(5), AH(6), IP-IP(7).' SYNTAX 'OCTETSTRING' ) ( radius radiusProfileClass 65 NAME 'radiusTunnelMediumType' DESC 'String representing the medium for the tunnel to run over, of the form Tag: Value. Values include IP(1), X.25(2), ATM(3), Frame Relay(4).' SYNTAX 'OCTETSTRING' ) ( radius radiusProfileClass 66 NAME 'radiusTunnelClientEndpoint' DESC 'String representing the Tunnel Client Endpoint for the tunnel, of the form Tag: Value.' SYNTAX 'OCTETSTRING' ) ( radius radiusProfileClass 67 NAME 'radiusTunnelServerEndpoint' DESC 'String representing the address of the tunnel server, of the form Tag: Value. The format of the value field depends on the tunnelMediumType attribute' SYNTAX 'OCTETSTRING' ) ( radius radiusProfileClass 71 NAME 'radiusArapFeatures' DESC 'This is a compound string containing info that the NAS should send to the user in the ARAP feature flags packet' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' SINGLE-VALUE ) ( radius radiusProfileClass 72 NAME 'radiusArapZoneAccess' Aboba Experimental [Page 19]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 DESC 'This field controls access to ARAP zones. Values include Only allow access to default zone(1), Use zone filter inclusively(2), Use zone filter exclusively (4)' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 73 NAME 'radiusArapSecurity' DESC 'This field contains an integer specifying the security module signature, which is a Macintosh OSType' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 75 NAME 'radiusPasswordRetry' DESC 'This is an integer specifying the number of password retry attempts to permit the user' EQUALITY integerMatch SYNTAX 'INTEGER SINGLE-VALUE ) ( radius radiusProfileClass 76 NAME 'radiusPrompt' DESC 'This attribute is used only in RADIUS Access-Challenge packets and indicates if the NAS should echo the user's response as entered. Values include No Echo (0), or Echo(1).' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 81 NAME 'radiusTunnelPrivateGroupId' DESC 'String representing the Private Group Id for the tunnel, of the form Tag: Value.' SYNTAX 'OCTETSTRING' ) ( radius radiusProfileClass 82 Aboba Experimental [Page 20]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 NAME 'radiusTunnelAssignmentId' DESC 'String representing the Tunnel Assignment Id for the tunnel, of the form Tag: Value.' SYNTAX 'OCTETSTRING' ) ( radius radiusProfileClass 83 NAME 'radiusTunnelPreference' DESC 'String representing the tunnel preference for the tunnel, of the form Tag: Value.' SYNTAX 'OCTETSTRING' ) ( radius radiusProfileClass 257 NAME 'npEAPType' DESC 'Allowable EAP types, in order of preference. If this attribute has a value, EAP must be included in the allowable authentication types.' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' SINGLE-VALUE ) ( radius radiusProfileClass 258 NAME 'npConstraint' DESC 'A string expressing conditions which must hold in order for an Access-Accept to be sent. The string is of the format MATCH ( <attribute> = <pattern/value> OR <pattern/value>) <AND/OR> TIMEOFDAY. Brackets () can be used to group. When multiple msNPConstraints are present, all of them must be satisfied in order for a profile to be executed.' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String' ) ( radius radiusProfileClass 259 NAME 'npIPPoolName' DESC 'The name of the IP Address Pool out of which the user's IP address should be allocated.' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String' ) ( radius radiusProfileClass 260 NAME 'npSessionsAllowed' DESC 'This attribute indicates the number of Aboba Experimental [Page 21]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 simultaneous sessions allowed for this user.' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 261 NAME 'npAuthenticationType' DESC 'Allowable authentication types (EAP, CHAP, PAP, MS-CHAP, etc.) in order of preference. If an attribute isn't included, it isn't allowed.' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' SINGLE-VALUE ) ( radius radiusProfileClass 262 NAME 'radiusProfilePointer' DESC 'Distinguished Name of a RADIUS Profile Object.' EQUALITY distinguishedNameMatch SYNTAX 'DN' SINGLE-VALUE ) ( radius radiusProfileClass 263 NAME 'radiusVendorId' DESC 'SMI Vendor Id. A non-zero value denotes a profile non-compliant with RFC 2138 and 2139.' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( radius radiusProfileClass 264 NAME 'radiusDictionaryPointer' DESC 'A Distinguished Name pointing to the RADIUS dictionary for this profile. If not present the default dictionary is used.' EQUALITY distinguishedNameMatch SYNTAX 'DN' SINGLE-VALUE ) Aboba Experimental [Page 22]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 8.2. New Attribute Types Used in the RADIUS Policy Class ( radius radiusPolicyClass 2 NAME 'npSequence' DESC 'An integer indicating the order in which policy objects are to be evaluated.' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) 8.3. New Attribute Types Used in the RADIUS Dictionary Class ( radius radiusDictionaryClass 1 NAME 'dictionaryEntry' DESC 'A dictionary entry in the RADIUS dictionary, of the form Attribute-Number:[Vendor-Type:]ldapDisplayName:Type. Vendor-Type may only be present with Attribute-Number=26 (Vendor Specific).' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' ) 8.4. New Attribute Types Used in the BIGCO Profile Class ( bigco bigcoProfileClass 263 NAME 'bigcoBapRequired' DESC 'This attribute indicates whether Bandwidth Allocation Protocol (BAP) is required for this user. Values include BAP Not Required (0) and BAP Required (1).' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( bigco bigcoProfileClass 264 NAME 'bigcoBapLinednLimit' DESC 'Percent of capacity utilized at which to bring a line down for this user. ' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE Aboba Experimental [Page 23]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 ) ( bigco bigcoProfileClass 265 NAME 'bigcoBapLinednTime' DESC 'Time in seconds for the capacity utilization calculation.' EQUALITY integerMatch SYNTAX 'INTEGER' SINGLE-VALUE ) ( bigco bigcoProfileClass 266 NAME 'bigcoDynDirServer' DESC 'Fully qualified domain name or IP address of the dynamic directory server for this user.' EQUALITY caseIgnoreIA5Match SYNTAX 'IA5String{128}' SINGLE-VALUE ) 9. Security issues Integration of a RADIUS server with an LDAP-based directory service can result in several security issues, including: Rogue LDAP-servers Inappropriate use These threats are discussed in turn. 9.1. Rogue LDAP servers Were a rogue LDAP server to respond to queries from the RADIUS server and have its responses accepted, it is possible that users could gain inappropriate access to the network. In order to protect against this, the conversation between the RADIUS server and the LDAP-based directory service SHOULD be mutually authenticated via TLS [8] or IPSEC [9]. 9.2. Inappropriate use This schema is intended for use by a RADIUS server integrating with an LDAP-enabled directory. This schema was not designed for use by devices looking to directly access the directory. Aboba Experimental [Page 24]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 LDAP-enabling a RADIUS server requires that the RADIUS server be given permissions to access a user's RADIUS objects and attributes. As a result, the administrator of the RADIUS server should exercise care to ensure that the RADIUS account password is not compromised. If at all possible, the RADIUS server should be physically secured. In contrast, LDAP-enabling of devices requires that devices be given these access-rights. This can be achieved by making the devices members of a group, and giving the group access rights to this portion of the schema. However, while RADIUS servers can often be physically secured, widely deployed devices typically cannot be. It should also be noted that direct use of LDAP across a WAN typically requires that LDAP pass through a firewall. This is problematic since LDAP-based directories can be used to store a wide variety of data, much of it sensitive. Thus without implementing an LDAP proxy to limit access only to appropriate portions of the schema, it is difficult to enforce security. Since humans are notoriously lax in administration of access rights, an attacker obtaining a device password would typically also obtain access not only to RADIUS attributes for every user, but to other information as well. LDAP-enabling of devices has other potential downsides as well. It increases the size of the device binaries, and may in some cases introduce dependencies in the device boot sequence that can be problematic. 10. Acknowledgments Thanks to Steven Judd, Ashwin Palekar, David Eitelbach, Narendra Gidwani and Donald Rule of Microsoft for useful discussions of this problem space. 11. References [1] Rigney, C., Rubens, A., Simpson W., and S. Willens, "Remote Authentication Dial In User Service (RADIUS)", RFC 2138, April 1997. [2] Rigney, C., "RADIUS Accounting", RFC 2139, April 1997. [3] Zorn, G., Leifer, D., Rubens, A., and J. Shriver, "RADIUS Attributes for Tunnel Protocol Support", Internet draft (work in progress), draft- ietf-radius-tunnel-auth-06.txt, September 1998. [4] Rigney, C., Willats, W., "RADIUS Extensions", Internet draft (work in progress), draft-ietf-radius-ext-02.txt, October 1998. Aboba Experimental [Page 25]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 [5] Wahl, M., Howes, T., Kille, S., "Lightweight Directory Access Protocol (v3)", RFC 2251, December 1997. [6] Wahl, M., Coulbeck, A., Howes, T., Kille S., "Lightweight Directory Access Protocol (v3): Attribute Syntax Definitions", RFC 2252, December 1997. [7] Blunk, L., Vollbrecht, J., "PPP Extensible Authentication Protocol (EAP)", RFC 2284, March 1998. [8] Dierks, T., Allen, C., "The TLS Protocol Version 1.0", RFC 2246, November 1998. [9] Atkinson, R., Kent, S., "Security Architecture for the Internet Protocol", RFC 2401, November 1998. [10] Case, J., McCloghrie, K., Rose, M., and S. Waldbusser, "Textual Conventions for Version 2 of the Simple Network Management Protocol (SNMPv2)", RFC 1903, January 1996. 12. Authors' Addresses Bernard Aboba Microsoft Corporation One Microsoft Way Redmond, WA 98052 Phone: 425-936-6605 EMail: bernarda@microsoft.com 13. Full Copyright Statement Copyright (C) The Internet Society (1999). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implmentation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except s needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are Aboba Experimental [Page 26]
INTERNET-DRAFT RADIUS Schema for LDAP v3 2 February 1999 perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS 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." 14. Expiration Date This memo is filed as <draft-aboba-radius-03.txt>, and expires August 1, 1999 Aboba Experimental [Page 27]