RADIUS Working Group C Rigney Internet Draft Livingston A Rubens Merit W A Simpson Daydreamer S Willens Livingston expires in six months May 1995 Remote Authentication Dial In User Service (RADIUS) draft-ietf-radius-radius-00.txt Status of this Memo This document is a submission to the RADIUS Working Group of the Internet Engineering Task Force (IETF). Comments should be submitted to the ietf-radius@livingston.com mailing list. Distribution of this memo is unlimited. This document is an Internet-Draft. 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 learn the current status of any Internet-Draft, please check the ``1id-abstracts.txt'' listing contained in the Internet-Drafts Shadow Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). Abstract This document describes a protocol for carrying authentication, authorization, and configuration information between a Network Access Server which desires to authenticate its links and a shared Authentication Server. Rigney, et alia expires in six months [Page i] DRAFT RADIUS Authentication May 1995 Table of Contents 1. Introduction .......................................... 1 1.1 Specification of Requirements ................... 2 1.2 Terminology ..................................... 2 2. Operation ............................................. 3 2.1 Challenge/Response .............................. 4 2.2 Interoperation with PAP and CHAP ................ 5 2.3 Why UDP? ........................................ 5 3. Packet Format ......................................... 7 4. Packet Types .......................................... 10 4.1 Access-Request .................................. 10 4.2 Access-Accept ................................... 11 4.3 Access-Reject ................................... 12 4.4 Access-Challenge ................................ 13 5. Attributes ............................................ 16 5.1 User-Name ....................................... 18 5.2 User-Password ................................... 19 5.3 CHAP-Password ................................... 20 5.4 NAS-IP-Address .................................. 20 5.5 NAS-Port ........................................ 21 5.6 Service-Type .................................... 22 5.7 Framed-Protocol ................................. 23 5.8 Framed-IP-Address ............................... 24 5.9 Framed-IP-Netmask ............................... 24 5.10 Framed-Routing .................................. 25 5.11 Filter-Id ....................................... 26 5.12 Framed-MTU ...................................... 27 5.13 Framed-Compression .............................. 27 5.14 Login-IP-Host ................................... 28 5.15 Login-Service ................................... 29 5.16 Login-Port ...................................... 30 5.17 (unassigned) .................................... 30 5.18 Reply-Message ................................... 31 5.19 Login-Callback-Number ........................... 32 5.20 Framed-Callback-Id .............................. 32 5.21 (unassigned) .................................... 33 5.22 Framed-Route .................................... 33 5.23 Framed-IPX-Network .............................. 34 5.24 State ........................................... 35 5.25 Class ........................................... 36 5.26 Vendor-Specific ................................. 37 5.27 Session-Timeout ................................. 38 Rigney, et alia expires in six months [Page ii] DRAFT RADIUS Authentication May 1995 5.28 Idle-Timeout .................................... 38 5.29 Termination-Action .............................. 39 5.30 Client-Port-DNIS ................................ 40 5.31 Caller-Id ....................................... 41 5.32 NAS-Identifier .................................. 42 5.33 Proxy-State ..................................... 43 5.34 Login-LAT-Service ............................... 44 5.35 Login-LAT-Node .................................. 45 5.36 Login-LAT-Group ................................. 46 5.37 Framed-AppleTalk-Link ........................... 47 5.38 Framed-AppleTalk-Network ........................ 47 5.39 Framed-AppleTalk-Zone ........................... 48 5.40 Table of Attributes ............................. 50 SECURITY CONSIDERATIONS ...................................... 52 REFERENCES ................................................... 53 ACKNOWLEDGEMENTS .......................................... 53 CHAIR'S ADDRESS .............................................. 54 AUTHOR'S ADDRESS ............................................. 54 Rigney, et alia expires in six months [Page iii] DRAFT RADIUS Authentication May 1995 1. Introduction Managing dispersed serial line and modem pools for large numbers of users can create the need for significant administrative support. Since modem pools are by definition a link to the outside world, they require careful attention to security, authorization and accounting. This can be best achieved by managing a single "database" of users, which allows for authentication (verifying user name and password) as well as configuration information detailing the type of service to deliver to the user (that is, SLIP, PPP, telnet, rlogin). Key features of RADIUS are: Client/Server Model A Network Access Server (NAS) operates as a client of RADIUS. The client is responsible for passing user information to designated RADIUS servers, and then acting on the response which is returned. RADIUS servers are responsible for receiving user connection requests, authenticating the user, and then returning all configuration information necessary for the client to deliver service to the user. The RADIUS servers can act as proxy clients to other kinds of authentication servers. Network Security Transactions between the client and RADIUS server are authenticated through the use of a shared secret, which is never sent over the network. In addition, any user passwords are sent encrypted between the client and RADIUS server, to eliminate the possibility that someone snooping on an unsecure network could determine a user's password. Flexible Authentication Mechanisms The RADIUS server supports a variety of methods to authenticate a user. When it is provided with the user name and original password given by the user, it can support PPP PAP or CHAP, UNIX login, and other authentication mechanisms. Extensible Protocol All transactions are comprised of variable length Attribute-Length-Value 3-tuples. New attribute values can be added without disturbing existing implementations of the protocol. Rigney, et alia expires in six months [Page 1] DRAFT RADIUS Authentication May 1995 Source Code Availability Livingston Enterprises is making the C source code for an example RADIUS server available without use restrictions. Other vendors have also implemented RADIUS. 1.1. Specification of Requirements In this document, several words are used to signify the requirements of the specification. These words are often capitalized. MUST This word, or the adjective "required", means that the definition is an absolute requirement of the specification. MUST NOT This phrase means that the definition is an absolute prohibition of the specification. SHOULD This word, or the adjective "recommended", means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications must be understood and carefully weighed before choosing a different course. MAY This word, or the adjective "optional", means that this item is one of an allowed set of alternatives. An implementation which does not include this option MUST be prepared to interoperate with another implementation which does include the option. 1.2. Terminology This document frequently uses the following terms: silently discard This means the implementation discards the packet without further processing. The implementation SHOULD provide the capability of logging the error, including the contents of the silently discarded packet, and SHOULD record the event in a statistics counter. Rigney, et alia expires in six months [Page 2] DRAFT RADIUS Authentication May 1995 2. Operation When a client is configured to use RADIUS, any user of the client presents authentication information to the client. This might be with a customizable login prompt, where the user is expected to enter their username and password. Alternatively, the user might use a link framing protocol such as the Point-to-Point Protocol (PPP), which has authentication packets which carry this information. Once the client has obtained such information, it first looks in its local database of users for the username. If found, the user is locally authenticated. If not found, the client will create an "Access-Request" containing such Attributes as the user's name, the user's password, the ID of the client and the Port ID which the user is accessing. When a password is present, it is hidden using a method based on the RSA Message Digest Algorithm MD5 [3]. The Access-Request is submitted to the RADIUS server via the network. If no response is returned within a configurable length of time, the request is re-sent a configurable number of times. After several failed attempts, the client can also forward requests to an alternate server in the event that the primary server is down or unreachable. Once the RADIUS server receives the request, it validates the sending client. The RADIUS server consults a local database of users to find the user whose name matches the request. The user entry in the database contains a list of requirements which must be met to allow access for the user. This always includes verification of the password, but can also specify the client(s) or Port(s) to which the user is allowed access. The RADIUS server MAY make requests of other servers in order to satisfy the request, in which case it acts as a client. If any condition is not met, the RADIUS server sends an "Access-Reject" response indicating that this user request is invalid. If desired, the server MAY also send a text message which MAY be displayed by the client to the user. No other Attributes are permitted in an "Access-Reject". If all conditions are met and the RADIUS server wishes to issue a challenge to which the user must respond, the RADIUS server sends an "Access-Challenge" response. If the client receives an Access-Challenge and supports challenge/response it MAY display the text message, if any, to the user, and then prompt the user for a response. It then re-submits its original Access-Request with a new request ID, with the Rigney, et alia expires in six months [Page 3] DRAFT RADIUS Authentication May 1995 User-Password Attribute replaced by the response (encrypted), and including the State Attribute from the "Access-Challenge", if any. Only 0 or 1 instances of the State Attributes should be present in a request. If all conditions are met, the list of configuration values for the user are placed into an "Access-Accept" response. These values include the type of service (for example: SLIP, PPP, Login User) and all necessary values to deliver the desired service. For SLIP and PPP, this may include values such as IP addresses, subnet masks, MTU, desired compression, and desired packet filters. For character mode users, this may include values such as desired protocol, host, and access control filter. 2.1. Challenge/Response In challenge/response authentication, individual users are given an unpredictable number and challenged to encrypt it and give back the result. Authorized users are equipped with special devices such as smart cards that facilitate calculation of the correct response with ease. Unauthorized users, lacking the appropriate device and lacking knowledge of the secret key necessary to emulate such a device, can only guess at the response. The Access-Challenge packet typically contains a Reply-Message including a challenge to be displayed to the user, such as a numeric value unlikely ever to be repeated. Typically this is obtained from an external server that knows what type of authenticator should be in the possession of the authorized user and can therefore choose a random or non-repeating pseudorandom number of an appropriate radix and length. The user then enters the challenge into his device and it calculates a response, which the user enters into the client which forwards it to the RADIUS server via a second Access-Request. If the response matches the expected response the RADIUS server replies with an Access-Accept, otherwise an Access-Reject. Example: The NAS sends an Access-Request packet to the RADIUS Server with NAS-Identifier, NAS-Port, User-Name, User-Password (which may just be a fixed string like "challenge" or ignored). The server sends back an Access-Challenge packet with State and a Reply-Message along the lines of "Challenge 12345678, enter your response at the prompt" which the NAS displays. The NAS prompts for the response and sends a NEW Access-Request to the server (with a new ID) with NAS-Identifier, NAS-Port, User-Name, User-Password (the response just entered by the user, encrypted), and the same State Attribute that Rigney, et alia expires in six months [Page 4] DRAFT RADIUS Authentication May 1995 came with the Access-Challenge. The server then sends back either an Access-Accept or Access-Reject based on whether the response matches what it should be, or it can even send another Access-Challenge. 2.2. Interoperation with PAP and CHAP For PAP, the NAS takes the PAP ID and password and sends them in an Access-Request packet as the User-Name and User-Password. The NAS MAY include the Attributes Service-Type = Framed-User and Framed-Protocol = PPP as a hint to the RADIUS server that PPP service is expected. For CHAP, the NAS generates a 16 octet random challenge and sends it to the user (the thing dialing in requesting authentication), which returns a CHAP response along with a CHAP ID and CHAP username. The NAS then sends an Access-Request packet to the RADIUS server with the CHAP username as the User-Name and with the CHAP ID and CHAP response as the CHAP-Password (Attribute 3). The random challenge is included in the Authenticator field of the Access-Request packet. The NAS MAY include the Attributes Service-Type = Framed-User and Framed-Protocol = PPP as a hint to the RADIUS server that PPP service is expected. The RADIUS server looks up the CHAP password based on the User-Name, encrypts the challenge, and compares that to the CHAP-Password. If they match, it sends back an Access-Accept, otherwise it sends back an Access-Reject. 2.3. Why UDP? A frequently asked question is why RADIUS uses UDP instead of TCP as a transport protocol. UDP was chosen for strictly technical reasons. There are a number of issues which must be understood. RADIUS is a transaction based protocol which has several interesting characteristics: 1. If the request to a primary Authentication server fails, a secondary server must be queried. To meet this requirement, a copy of the request must be kept above the transport layer to allow for alternate transmission. This means that retransmission timers are still required. 2. The timing requirements of this particular protocol are significantly different than TCP provides. At one extreme, RADIUS does not require a "responsive" detection Rigney, et alia expires in six months [Page 5] DRAFT RADIUS Authentication May 1995 of lost data. The user is willing to wait several seconds for the authentication to complete. The generally aggressive TCP retransmission (based on average round trip time) is not required, nor is the acknowledgement overhead of TCP. At the other extreme, the user is not willing to wait several minutes for authentication. Therefore the reliable delivery of TCP data two minutes later is not useful. The faster use of an alternate server allows the user to gain access before giving up. 3. The stateless nature of this protocol simplifies the use of UDP. Clients and servers come and go. Systems are rebooted, or are power cycled independently. Generally this does not cause a problem and with creative timeouts and detection of lost TCP connections, code can be written to handle anomalous events. UDP however completely eliminates any of this special handling. Each client and server can open their UDP transport just once and leave it open through all types of failure events on the network. 4. UDP simplifies the server implementation. In the earliest implementations of RADIUS, the server was single threaded. This means that a single request was received, processed, and returned. This was found to be unmanageable in environments where the back-end security mechanism took real time (1 or more seconds). The server request queue would fill and in environments where hundreds of people where being authenticated every minute, the request turn-around time increased to longer that users were willing to wait (this was especially severe when a specific lookup in a database or over DNS took 30 or more seconds). The obvious solution was to make the server multi-threaded. Achieving this was simple with UDP. Separate processes were spawned to serve each request and these processes could respond directly to the client NAS with a simple UDP packet to the original transport of the client. It's not all a panacea. As noted, using UDP requires one thing which is built into TCP: with UDP we must artificially manage retransmission timers to the same server, although they don't require the same attention to timing provided by TCP. This one penalty is a small price to pay for the advantages of UDP in this protocol. Without TCP we would still probably be using tin cans connected by string. But for this particular protocol, UDP is a better choice. Rigney, et alia expires in six months [Page 6] DRAFT RADIUS Authentication May 1995 3. Packet Format Exactly one RADIUS packet is encapsulated in the UDP Data field [1], where the UDP Destination Port field indicates 1645. When a reply is generated, the source and destination ports are reversed. A summary of the RADIUS data format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Code | Identifier | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Authenticator | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attributes ... +-+-+-+-+-+-+-+-+-+-+-+-+- Code The Code field is one octet, and identifies the type of RADIUS packet. When a packet is received with an invalid Code field, it is silently discarded. RADIUS Codes (decimal) are assigned as follows: 1 Access-Request 2 Access-Accept 3 Access-Reject 4 Accounting-Request 5 Accounting-Response 11 Access-Challenge 12 Status-Server (experimental) 13 Status-Client (experimental) 255 Reserved Codes 4 and 5 will be covered in the RADIUS Accounting Internet- Draft, and are not further mentioned here. Codes 12 and 13 are reserved for possible use, but may be unallocated in a future draft. They are not further mentioned here. Rigney, et alia expires in six months [Page 7] DRAFT RADIUS Authentication May 1995 Identifier The Identifier field is one octet, and aids in matching requests and replies. Length The Length field is two octets. It indicates the length of the packet including the Code, Identifier, Length, Authenticator and Attribute fields. Octets outside the range of the Length field should be treated as padding and should be ignored on reception. Authenticator The Authenticator field is sixteen (16) octets. The most significant octet is transmitted first. This value is used to authenticate the reply from the RADIUS server, and is used in the password hiding algorithm. Request Authenticator In Access-Request Packets, the Authenticator value is a 16 octet random number. The value SHOULD be unique and unpredictable. In Access-Request packets, the Authenticator value SHOULD be unique over the lifetime of a secret (the password shared between the client and the RADIUS server), since repetition of a request value in conjunction with the same secret would permit an attacker to reply with a previously intercepted response. Since it is expected that the same secret MAY be used to authenticate with servers in disparate geographic regions, the request authenticator field SHOULD exhibit global and temporal uniqueness. Each Authenticator value in Access-Request packets SHOULD also be unpredictable, lest an attacker trick a server into responding to a predicted future request, and then use the response to masquerade as that server to another authenticator. Although protocols such as RADIUS are incapable of protecting against theft of an authenticated session via realtime active wiretapping attacks, generation of unique unpredictable requests can protect against a wide range of active attacks against authentication. The NAS and RADIUS server share a secret. That shared secret followed by the Authenticator is put through a one-way MD5 hash to create a 16 octet digest value which is xored with the User-Password in the Access-Request packet. Rigney, et alia expires in six months [Page 8] DRAFT RADIUS Authentication May 1995 Response Authenticator The Authenticator field in Access-Accept, Access-Reject, and Access-Challenge packets contains a one-way MD5 hash calculated over a stream of octets consisting of the RADIUS packet, beginning with the Code field, including the Identifier, the Length, the Authenticator field from the Access-Request packet, and the response Attributes, followed by (concatenated with) a "shared secret". Administrative Note The secret (password shared between the client and the RADIUS server) SHOULD be at least as large and unguessable as a well-chosen password. It is preferred that the secret be at least 16 octets. This is to ensure a sufficiently large range for the secret to provide protection against exhaustive search attacks. Attributes Many Attributes may have multiple instances, in such a case the order of Attributes of the same Type SHOULD be preserved. The order of Attributes of different Types is not required to be preserved. Rigney, et alia expires in six months [Page 9] DRAFT RADIUS Authentication May 1995 4. Packet Types The RADIUS Packet type is determined by the Code field in the first octet of the Packet. 4.1. Access-Request Description Access-Request packets are sent to a RADIUS server, and convey information used to determine whether a user is allowed access to a specific NAS, and any special services requested for that user. An implementation wishing to Authenticate a user MUST transmit a RADIUS packet with the Code field set to 1 (Access-Request). Upon receipt of an Access-Request, an appropriate reply MUST be transmitted. An Access-Request MUST contain a User-Name atttribute. It MUST contain either a NAS-IP-Address attribute or NAS-Identifier attribute (or both, although that is not recommended). It MUST contain either a User-Password attribute or CHAP-Password attribute. It SHOULD contain a NAS-Port attribute unless the type of access being requested does not involve a port or the NAS does not distinguish among its ports. It MAY contain additional attributes as a hint to the server. When a password is present, it is hidden using a method based on the RSA Message Digest Algorithm MD5 [3]. A summary of the Access-Request packet format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Code | Identifier | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Authenticator | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attributes ... +-+-+-+-+-+-+-+-+-+-+-+-+- Rigney, et alia expires in six months [Page 10] DRAFT RADIUS Authentication May 1995 Code 1 for Access-Request. Identifier The Identifier field MUST be changed whenever the content of the Attributes field changes, and whenever a valid reply has been received for a previous request. For retransmissions, the Identifier MAY remain unchanged. Authenticator The Authenticator value MUST be changed each time a new Identifier is used. Attributes The Attribute field is variable in length, and contains the list of Attributes that are required for the type of service, as well as any desired optional Attributes. 4.2. Access-Accept Description Access-Accept packets are sent by the RADIUS server, and provide specific configuration information necessary to begin delivery of services to the user. If all Attribute values received in an Access-Request are acceptable then the RADIUS implementation MUST transmit a packet with the Code field set to 2 (Access-Accept). On reception of an Access-Accept, the Identifier field is matched with a pending Access-Request. Additionally, the Authenticator field MUST contain the correct response for the pending Access-Request. Invalid packets are silently discarded. A summary of the Access-Accept packet format is shown below. The fields are transmitted from left to right. Rigney, et alia expires in six months [Page 11] DRAFT RADIUS Authentication May 1995 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Code | Identifier | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Authenticator | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attributes ... +-+-+-+-+-+-+-+-+-+-+-+-+- Code 2 for Access-Accept. Identifier The Identifier field is a copy of the Identifier field of the Access-Request which caused this Access-Accept. Authenticator The Authenticator value is calculated from the Access-Request value, as described earlier. Attributes The Attribute field is variable in length, and contains a list of zero or more Attributes. 4.3. Access-Reject Description If any value of the received Attributes is not acceptable, then the RADIUS server MUST transmit a packet with the Code field set to 3 (Access-Reject). It MAY include one or more Reply-Message Attributes with a text message which the NAS MAY display to the user. A summary of the Access-Reject packet format is shown below. The fields are transmitted from left to right. Rigney, et alia expires in six months [Page 12] DRAFT RADIUS Authentication May 1995 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Code | Identifier | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Authenticator | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attributes ... +-+-+-+-+-+-+-+-+-+-+-+-+- Code 3 for Access-Reject. Identifier The Identifier field is a copy of the Identifier field of the Access-Request which caused this Access-Reject. Authenticator The Authenticator value is calculated from the Access-Request value, as described earlier. Attributes The Attribute field is variable in length, and contains a list of zero or more Attributes. 4.4. Access-Challenge Description If the RADIUS server desires to send the user a challenge requiring a response, then the RADIUS server MUST respond to the Access-Request by transmitting a packet with the Code field set to 11 (Access-Challenge). The Attributes field MAY have one or more Reply-Message Attributes, and MAY have a single State Attribute, or none. No other Attributes are permitted in an Access-Challenge. Rigney, et alia expires in six months [Page 13] DRAFT RADIUS Authentication May 1995 On receipt of an Access-Challenge, the Identifier field is matched with a pending Access-Request. Additionally, the Authenticator field MUST contain the correct response for the pending Access-Request. Invalid packets are silently discarded. If the NAS supports challenge/response, receipt of a valid Access-Challenge indicates that a new Access-Request SHOULD be submitted. The NAS MAY display the text message, if any, to the user, and then prompt the user for a response. It then re-submits its original Access-Request with a new request ID, with the User-Password Attribute replaced by the user's response (encrypted), and including the State Attribute from the "Access-Challenge", if any. Only 0 or 1 instances of the State Attribute can be present in a request. A NAS which supports PAP MAY forward the Reply-Message to the dialin client and accept a PAP response which it can use as though the user had entered the response. A summary of the Access-Challenge packet format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Code | Identifier | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | Authenticator | | | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Attributes ... +-+-+-+-+-+-+-+-+-+-+-+-+- Code 11 for Access-Challenge. Identifier The Identifier field is a copy of the Identifier field of the Access-Request which caused this Access-Challenge. Authenticator The Authenticator value is calculated from the Access-Request Rigney, et alia expires in six months [Page 14] DRAFT RADIUS Authentication May 1995 value, as described earlier. Attributes The Attributes field is variable in length, and contains a list of zero or more Attributes. Rigney, et alia expires in six months [Page 15] DRAFT RADIUS Authentication May 1995 5. Attributes RADIUS Attributes carry the specific authentication, authorization, information and configuration details for the request and reply. Some Attributes MAY be listed more than once. The effect of this is Attribute specific, and is specified by each such Attribute description. The end of the list of Attributes is indicated by the length of the RADIUS packet. A summary of the Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | Value ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type The Type field is one octet. Up-to-date values of the RADIUS Type field are specified in the most recent "Assigned Numbers" RFC [2]. Values 192-223 are reserved for experimental use, values 224-240 are reserved for implementation-specific use, and values 241-255 are reserved and should not be used. This specification concerns the following values: 1 User-Name 2 User-Password 3 CHAP-Password 4 NAS-IP-Address 5 NAS-Port 6 Service-Type 7 Framed-Protocol 8 Framed-IP-Address 9 Framed-IP-Netmask 10 Framed-Routing 11 Filter-Id 12 Framed-MTU 13 Framed-Compression 14 Login-IP-Host 15 Login-Service 16 Login-Port 17 (unassigned) Rigney, et alia expires in six months [Page 16] DRAFT RADIUS Authentication May 1995 18 Reply-Message 19 Login-Callback-Number 20 Framed-Callback-Id 21 (unassigned) 22 Framed-Route 23 Framed-IPX-Network 24 State 25 Class 26 Vendor-Specific 27 Session-Timeout 28 Idle-Timeout 29 Termination-Action 30 Client-Port-DNIS 31 Caller-ID 32 NAS-Identifier 33 Proxy-State 34 Login-LAT-Service 35 Login-LAT-Node 36 Login-LAT-Group 37 Framed-AppleTalk-Link 38 Framed-AppleTalk-Network 39 Framed-AppleTalk-Zone 40-49 Reserved for Accounting Length The Length field is one octet, and indicates the length of this Attribute including the Type, Length and Value fields. If an Attribute is received in a Access-Request but with an invalid Length, an Access-Reject SHOULD be transmitted. Value The Value field is zero or more octets and contains information specific to the Attribute. The format and length of the Value field is determined by the Type and Length fields. The format of the value field is one of four data types. string 0-253 octets address 32 bit value, most significant octet first. integer 32 bit value, most significant octet first. time 32 bit value, most significant octet first -- seconds since 00:00:00 GMT, January 1, 1970. Rigney, et alia expires in six months [Page 17] DRAFT RADIUS Authentication May 1995 5.1. User-Name Description This Attribute indicates the name of the user to be authenticated. It is only used in Access-Request packets. A summary of the User-Name Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 1 for User-Name. Length >= 3 String The String field is one or more octets. The NAS may limit the maximum length of the User-Name but the ability to handle at least 63 octets is recommended. The format of the username MAY be one of several forms: monolithic Consisting only of alphanumeric characters. This simple form might be used to locally manage a NAS. simple Consisting only of printable ASCII characters. name@fqdn SMTP address. The Fully Qualified Domain Name (with or without trailing dot) indicates the realm in which the name part applies. distinguished name A name in ASN.1 form used in Public Key authentication systems. Rigney, et alia expires in six months [Page 18] DRAFT RADIUS Authentication May 1995 5.2. User-Password Description This Attribute indicates the password of the user to be authenticated, or the user's input following an Access-Request. It is only used in Access-Request packets. On transmission, the password is hidden. A one-way MD5 hash is calculated over a stream of octets consisting of the "shared secret", followed by (concatenated with) the Request Authenticator. This value is xor'd with each successive 16 octet segment of the password. Note that this encryption scheme is very strong for passwords 16 octets or shorter and quite weak for passwords longer than 16 octets. Alternative methods to allow longer passwords to be safely used are the topic of further research. On receipt, the same mask is created. Repeating the xor function yields the original password. A summary of the User-Password Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 2 for User-Password. Length >= 18 String The String field is one or more octets. Rigney, et alia expires in six months [Page 19] DRAFT RADIUS Authentication May 1995 5.3. CHAP-Password Description This Attribute indicates the response value provided by a PPP Challenge-Handshake Authentication Protocol (CHAP) user in response to the challenge. It is only used in Access-Request packets. The CHAP challenge value is found in the RADIUS Authenticator field. A summary of the CHAP-Password Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | CHAP Ident | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 3 for CHAP-Password. Length >= 19 CHAP Ident This field is one octet, and contains the CHAP Identifier from the CHAP Response packet. String The String field is 16 octets when MD5 is used for CHAP. 5.4. NAS-IP-Address Description This Attribute indicates the identifying IP Address of the NAS which is authenticating the user. It is only used in Access-Request packets. Either NAS-IP-Address or NAS-Identifier Rigney, et alia expires in six months [Page 20] DRAFT RADIUS Authentication May 1995 MUST be present in an Access-Request packet. A summary of the NAS-IP-Address Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Address (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 4 for NAS-IP-Address. Length 6 Address The Address field is four octets. 5.5. NAS-Port Description This Attribute indicates the port number of the NAS which is authenticating the user. It is only used in Access-Request packets. A summary of the NAS-Port Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Rigney, et alia expires in six months [Page 21] DRAFT RADIUS Authentication May 1995 Type 5 for NAS-Port. Length 6 Value The Value field is four octets. Despite the rather large size of the field, values range from 0 to 65535. 5.6. Service-Type Description This Attribute indicates the type of link the user has requested, or a change in the type of link to be configured. It is used in both Access-Request and Access-Accept packets. A summary of the Service-Type Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 6 for Service-Type. Length 6 Value The Value field is four octets. Rigney, et alia expires in six months [Page 22] DRAFT RADIUS Authentication May 1995 1 Login 2 Framed 3 Callback Login 4 Callback Framed 5 Outbound User 6 Administrative User 7 Exec User 8 Authenticate Only 5.7. Framed-Protocol Description This Attribute indicates the framing to be used for framed access. It is used in both Access-Request and Access-Accept packets. A summary of the Framed-Protocol Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 7 for Framed-Protocol. Length 6 Value The Value field is four octets. 1 PPP 2 SLIP Rigney, et alia expires in six months [Page 23] DRAFT RADIUS Authentication May 1995 5.8. Framed-IP-Address Description This Attribute indicates the address to be configured for the user. It is only used in Access-Accept packets. A summary of the Framed-IP-Address Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Address (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 8 for Framed-IP-Address. Length 6 Address The Address field is four octets. The value 0xFFFFFFFF indicates that the NAS should allow the user to select an address (e.g. Negotiated). The value 0xFFFFFFFE indicates that the NAS should select an address for the user (e.g. Assigned from a pool of addresses kept by the NAS). 5.9. Framed-IP-Netmask Description This Attribute indicates the IP netmask to be configured for the user when the user is a router to a network. It is unnecessary when routing is used. It is only used in Access-Accept packets. A summary of the Framed-IP-Netmask Attribute format is shown below. The fields are transmitted from left to right. Rigney, et alia expires in six months [Page 24] DRAFT RADIUS Authentication May 1995 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Netmask +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Netmask (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 9 for Framed-IP-Netmask. Length 6 Netmask The Netmask field is four octets. 5.10. Framed-Routing Description This Attribute indicates the routing method for the user, when the user is a router to a network. It is only used in Access-Accept packets. A summary of the Framed-Routing Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 10 for Framed-Routing. Rigney, et alia expires in six months [Page 25] DRAFT RADIUS Authentication May 1995 Length 6 Value The Value field is four octets. 0 None 1 Send routing packets 2 Listen for routing packets 3 Send and Listen 5.11. Filter-Id Description This Attribute indicates the name of the filter list for this user. Using a name for a filter list allows independence from multiple NAS implementations. However, the name used might be dependent on the NAS making the request, rather than the user. A summary of the Filter-Id Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 11 for Filter-Id. Length >= 3 String The String field is one or more octets. Rigney, et alia expires in six months [Page 26] DRAFT RADIUS Authentication May 1995 5.12. Framed-MTU Description This Attribute indicates the Maximum Transmission Unit to be configured for the user, when it is not negotiated by some other means (such as PPP). It is only used in Access-Accept packets. A summary of the Framed-MTU Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 12 for Framed-MTU. Length 6 Value The Value field is four octets. Despite the rather large size of the field, values range from 64 to 65535. 5.13. Framed-Compression Description This Attribute indicates a compression protocol to be used for the link. More than one compression protocol Attribute MAY be sent. It is the responsibility of the NAS to apply the proper compression protocol to appropriate link traffic. A summary of the Framed-Compression Attribute format is shown below. The fields are transmitted from left to right. Rigney, et alia expires in six months [Page 27] DRAFT RADIUS Authentication May 1995 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 13 for Framed-Compression. Length 6 Value The Value field is four octets. 1 VJ TCP/IP header compression 2 IPX header compression 5.14. Login-IP-Host Description This Attribute indicates the system with which the user is to be automatically connected, when the Login-Service Attribute is listed. It is only used in Access-Accept packets. A summary of the Login-IP-Host Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Address +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Address (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Rigney, et alia expires in six months [Page 28] DRAFT RADIUS Authentication May 1995 Type 14 for Login-IP-Host. Length 6 Address The Address field is four octets. The value 0xFFFFFFFF indicates that the NAS SHOULD allow the user to select an address. The value 0 indicates that the NAS SHOULD select a host to connect the user to. 5.15. Login-Service Description This Attribute indicates the service with which the user is to be automatically connected. It is only used in Access-Accept packets. A summary of the Login-Service Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 15 for Login-Service. Length 6 Value The Value field is four octets. Rigney, et alia expires in six months [Page 29] DRAFT RADIUS Authentication May 1995 0 Telnet 1 Rlogin 2 TCP 3 Portmaster (proprietary) 4 LAT 5.16. Login-Port Description This Attribute indicates the TCP (or LAT) port with which the user is to be automatically connected, when the Login-Service Attribute is also present. It is only used in Access-Accept packets. A summary of the Login-Port Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 16 for Login-Port. Length 6 Value The Value field is four octets. Despite the rather large size of the field, values range from 0 to 65535. 5.17. (unassigned) Description Rigney, et alia expires in six months [Page 30] DRAFT RADIUS Authentication May 1995 ATTRIBUTE TYPE 17 HAS NOT BEEN ASSIGNED. 5.18. Reply-Message Description This Attribute indicates text which MAY be displayed to the user. When used in an Access-Accept, it is the success message. When used in an Access-Reject, it is the failure message. It MAY indicate a dialog message to prompt the user before another Access-Request attempt. When used in an Access-Challenge, it MAY indicate a dialog message to prompt the user for a response. Multiple Reply-Message's MAY be included and if any are displayed, they MUST be displayed in the same order as they appear in the packet. A summary of the Reply-Message Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 18 for Reply-Message. Length >= 3 String The String field is one or more octets, and its contents are implementation dependent. It is intended to be human readable, and MUST NOT affect operation of the protocol. It is recommended that the message contain displayable ASCII characters 32 through 126 decimal. Mechanisms for extension to other character sets are Rigney, et alia expires in six months [Page 31] DRAFT RADIUS Authentication May 1995 the topic of future research. 5.19. Login-Callback-Number Description This Attribute indicates a dialing string to be used for callback. It is used in both Access-Request and Access-Accept packets. A summary of the Login-Callback-Number Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 19 for Login-Callback-Number. Length >= 3 String The String field is one or more octets. The actual format of the information is site or application specific, and a robust implementation SHOULD support the field as undistinguished octets. It is intended that only an authorized user will have correct site specific information to make use of the Callback. The codification of the range of allowed usage of this field is outside the scope of this specification. 5.20. Framed-Callback-Id Description This Attribute indicates the name of a place to be called. It can be used in Access-Accept packets. Rigney, et alia expires in six months [Page 32] DRAFT RADIUS Authentication May 1995 A summary of the Framed-Callback-Id Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 20 for Framed-Callback-Id. Length >= 3 String The String field is one or more octets. The actual format of the information is site or application specific, and a robust implementation SHOULD support the field as undistinguished octets. It is intended that only an authorized user will have correct site specific information to make use of the Callback. The codification of the range of allowed usage of this field is outside the scope of this specification. 5.21. (unassigned) Description ATTRIBUTE TYPE 21 HAS NOT BEEN ASSIGNED. 5.22. Framed-Route Description This Attribute provides routing information to be configured for the user. It is used in the Access-Accept packet and can appear multiple times. A summary of the Framed-Route Attribute format is shown below. The Rigney, et alia expires in six months [Page 33] DRAFT RADIUS Authentication May 1995 fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 22 for Framed-Route. Length >= 3 String The String field is one or more octets, and its contents are implementation dependent. It is intended to be human readable and MUST NOT affect operation of the protocol. It is recommended that the message contain displayable ASCII characters 32 through 126 decimal. It MAY contain a destination address in dotted quad form, a space, a gateway address in dotted quad form, a space, and a decimal metric, for example, "199.9.200.0 192.9.200.1 1". Whenever the gateway address is specified as "0.0.0.0" the IP address of the user SHOULD be used as the gateway address. 5.23. Framed-IPX-Network Description This Attribute indicates the IPX Network number to be configured for the user. It is used in Access-Accept packets. A summary of the Framed-IPX-Network Attribute format is shown below. The fields are transmitted from left to right. Rigney, et alia expires in six months [Page 34] DRAFT RADIUS Authentication May 1995 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 23 for Framed-IPX-Network. Length 6 Value The Value field is four octets. The value 0xFFFFFFFE indicates that the NAS should select an IPX network for the user (e.g. Assigned from a pool of ipx networks kept by the NAS). 5.24. State Description This Attribute is available to be sent by the server to the client in an Access-Challenge and should be sent unmodified from the client to the server in the new Access-Request reply to that Challenge, if any. No interpretation by the client should be made. A packet may have only one State Attribute. Usage of the State Attribute is implementation dependent. A summary of the State Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Rigney, et alia expires in six months [Page 35] DRAFT RADIUS Authentication May 1995 Type 24 for State. Length >= 3 String The String field is one or more octets. The actual format of the information is site or application specific, and a robust implementation SHOULD support the field as undistinguished octets. The codification of the range of allowed usage of this field is outside the scope of this specification. 5.25. Class Description This Attribute is available to be sent by the server to the client in an Access-Accept and should be sent unmodified by the client to the accounting server as part of the Accounting-Request packet if accounting is supported. No interpretation by the client should be made. A summary of the Class Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 25 for Class. Length >= 3 Rigney, et alia expires in six months [Page 36] DRAFT RADIUS Authentication May 1995 String The String field is one or more octets. The actual format of the information is site or application specific, and a robust implementation SHOULD support the field as undistinguished octets. The codification of the range of allowed usage of this field is outside the scope of this specification. 5.26. Vendor-Specific Description This Attribute is available to allow vendors to support their own extended Attributes not suitable for general usage. It MUST not affect the operation of the RADIUS protocol. A summary of the Vendor-Specific Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Vendor-Id +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Vendor-Id (cont) | String... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 26 for Vendor-Specific. Length >= 7 Vendor-Id The high-order octet is 0 and the low-order 3 octets is the OID of the Vendor, as defined in the Assigned Numbers RFC [2]. String The String field is one or more octets. The actual format of the information is site or application specific, and a robust implementation SHOULD support the field as undistinguished octets. Rigney, et alia expires in six months [Page 37] DRAFT RADIUS Authentication May 1995 The codification of the range of allowed usage of this field is outside the scope of this specification. 5.27. Session-Timeout Description This Attribute sets the maximum number of seconds of service to be provided to the user before termination of the session. This Attribute is available to be sent by the server to the client in an Access-Accept. A summary of the Session-Timeout Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 27 for Session-Timeout. Length 6 Value The field is 4 octets, containing a 32-bit unsigned integer with the maximum number of seconds this user should be allowed to remain connected by the NAS. 5.28. Idle-Timeout Description This Attribute sets the maximum number of consecutive seconds of idle connection allowed to the user before termination of the Rigney, et alia expires in six months [Page 38] DRAFT RADIUS Authentication May 1995 session. This Attribute is available to be sent by the server to the client in an Access-Accept. A summary of the Idle-Timeout Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 28 for Idle-Timeout. Length 6 Value The field is 4 octets, containing a 32-bit unsigned integer with the maximum number of consecutive seconds of idle time this user should be permitted before being disconnected by the NAS. 5.29. Termination-Action Description This Attribute indicates what action the NAS should take when the specified service is completed. It is only used in Access-Accept packets. A summary of the Termination-Action Attribute format is shown below. The fields are transmitted from left to right. Rigney, et alia expires in six months [Page 39] DRAFT RADIUS Authentication May 1995 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 29 for Termination-Action. Length 6 Value The Value field is four octets. 0 Default 1 RADIUS-Request If the Value is set to RADIUS-Request, upon termination of the specified service the NAS MAY send a new Access-Request to the RADIUS server, including the State attribute if any. 5.30. Client-Port-DNIS Description This Attribute allows the NAS to send in the Access-Request packet the phone number that the call came in on, using DNIS or similar technology. It is only used in Access-Request packets. [NOTE! A better name for this attribute is sought.] A summary of the Client-Port-DNIS Attribute format is shown below. The fields are transmitted from left to right. Rigney, et alia expires in six months [Page 40] DRAFT RADIUS Authentication May 1995 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 30 for Client-Port-DNIS. Length >= 3 String The String field is one or more octets, containing the phone number that the user's call came in on. The actual format of the information is site or application specific. Printable ASCII is recommended, but a robust implementation SHOULD support the field as undistinguished octets. The codification of the range of allowed usage of this field is outside the scope of this specification. 5.31. Caller-Id Description This Attribute allows the NAS to send in the Access-Request packet the phone number that the call came from, using ANI or similar technology. It is only used in Access-Request packets. A summary of the Caller-Id Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Rigney, et alia expires in six months [Page 41] DRAFT RADIUS Authentication May 1995 Type 31 for Caller-Id. Length >= 3 String The String field is one or more octets, containing the phone number that the user placed the call from. The actual format of the information is site or application specific. Printable ASCII is recommended, but a robust implementation SHOULD support the field as undistinguished octets. The codification of the range of allowed usage of this field is outside the scope of this specification. 5.32. NAS-Identifier Description This Attribute contains a string identifying the NAS originating the Access-Request. It is only used in Access-Request packets. Either NAS-IP-Address or NAS-Identifier must be present in an Access-Request packet. A summary of the NAS-Identifier Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 32 for NAS-Identifier. Length >= 3 Rigney, et alia expires in six months [Page 42] DRAFT RADIUS Authentication May 1995 String The String field is one or more octets, and should be unique to the NAS within the scope of the RADIUS server. For example, a fully qualified domain name would be suitable as a NAS-Identifier. The actual format of the information is site or application specific, and a robust implementation SHOULD support the field as undistinguished octets. The codification of the range of allowed usage of this field is outside the scope of this specification. 5.33. Proxy-State Description This Attribute is available to be sent by a proxy server to another server when forwarding an Access-Request and should be returned unmodified in the Access-Accept, Access-Reject or Access-Challenge. This attribute should be removed by the proxy server before the response is forwarded to the NAS. Usage of the Proxy-State Attribute is implementation dependent. A description of its function is outside the scope of this specification. A summary of the Proxy-State Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 33 for Proxy-State. Length >= 3 String The String field is one or more octets. The actual format of the Rigney, et alia expires in six months [Page 43] DRAFT RADIUS Authentication May 1995 information is site or application specific, and a robust implementation SHOULD support the field as undistinguished octets. The codification of the range of allowed usage of this field is outside the scope of this specification. 5.34. Login-LAT-Service Description This Attribute indicates the system with which the user is to be automatically connected by LAT. It is only used in Access-Accept packets. It is used only when LAT is specified as the Login-Service. Administrators use the service attribute when dealing with clustered systems, such as a VAX or Alpha cluster. In such an environment several different time sharing hosts share the same resources (disks, printers, etc.), and administrators often configure each to offer access (service) to each of the shared resources. In this case, each host in the cluster advertises its services through LAT broadcasts. Sophisticated users often know which service providers (machines) are faster and tend to use a node name when initiating a LAT connection. Alternately, some administrators want particular users to use certain machines as a primitive form of load balancing (although LAT knows how to do load balancing itself). A summary of the Login-LAT-Service Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 34 for Login-LAT-Service. Length >= 3 Rigney, et alia expires in six months [Page 44] DRAFT RADIUS Authentication May 1995 String The String field is one or more octets, and contains the identity of the LAT service to use. A robust implementation SHOULD support the field as undistinguished octets. The codification of the range of allowed usage of this field is outside the scope of this specification. 5.35. Login-LAT-Node Description This Attribute indicates the Node with which the user is to be automatically connected by LAT. It is only used in Access-Accept packets. It is used only when LAT is specified as the Login-Service. A summary of the Login-LAT-Node Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 35 for Login-LAT-Node. Length >= 3 String The String field is one or more octets, and contains the identity of the LAT Node to connect the user to. A robust implementation SHOULD support the field as undistinguished octets. The codification of the range of allowed usage of this field is outside the scope of this specification. Rigney, et alia expires in six months [Page 45] DRAFT RADIUS Authentication May 1995 5.36. Login-LAT-Group Description This Attribute contains a string identifying the LAT group codes which this user is authorized to use. It is only used in Access-Request packets. It is used only when LAT is specified as the Login-Service. LAT supports 256 different group codes, which LAT uses as a form of access rights. LAT encodes the group codes as a 256 bit bitmap. Administrators can assign one or more of the group code bits at the LAT service provider; it will only accept LAT connections that have these group codes set in the bit map. Then the administrators assign a bit map of authorized group codes to each user; LAT gets these from the operating system, and uses these in its requests to the service providers. A summary of the Login-LAT-Group Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Type 36 for Login-LAT-Group. Length 34 String The String field is a 32 octet bit map, most significant octet first. A robust implementation SHOULD support the field as undistinguished octets. The codification of the range of allowed usage of this field is outside the scope of this specification. Rigney, et alia expires in six months [Page 46] DRAFT RADIUS Authentication May 1995 5.37. Framed-AppleTalk-Link Description This Attribute indicates the AppleTalk network number which should be used for the serial link to the user, which is another AppleTalk router. It is only used in Access-Accept packets. It is never used when the user is not another router. A summary of the Framed-AppleTalk-Link Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 37 for Framed-Appletalk-Link. Length 6 Value The Value field is four octets. Despite the rather large size of the field, values range from 0 to 65535. The special value of 0 indicates that this is an unnumbered serial link. A value of 1-65535 means that the serial line between the NAS and the user should be assigned that value as a network number. 5.38. Framed-AppleTalk-Network Description This Attribute indicates the AppleTalk Network number which the NAS should probe to allocate an address for the user. It is only used in Access-Accept packets. It is never used when the user is another router. Multiple instances of this Attribute indicate that the NAS may probe using any of the network numbers specified. Rigney, et alia expires in six months [Page 47] DRAFT RADIUS Authentication May 1995 A summary of the Framed-AppleTalk-Network Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Value +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Value (cont) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 38 for Framed-Appletalk-Network. Length 6 Value The Value field is four octets. Despite the rather large size of the field, values range from 0 to 65535. The special value 0 indicates that the NAS should assign a network for the user, using its default cable range. A value between 1 and 65535 (inclusive) indicates the AppleTalk Network the NAS should probe to find an address for the user. 5.39. Framed-AppleTalk-Zone Description This Attribute indicates the AppleTalk Default Zone to be used for this user. It is only used in Access-Accept packets. Multiple instances of this attribute in the same packet are not allowed. A summary of the Framed-Appletalk-Zone Attribute format is shown below. The fields are transmitted from left to right. 0 1 2 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- | Type | Length | String ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Rigney, et alia expires in six months [Page 48] DRAFT RADIUS Authentication May 1995 Type 39 for Framed-Appletalk-Zone. Length >= 3 String The name of the Default AppleTalk Zone to be used for this user. A robust implementation SHOULD support the field as undistinguished octets. The codification of the range of allowed usage of this field is outside the scope of this specification. Rigney, et alia expires in six months [Page 49] DRAFT RADIUS Authentication May 1995 5.40. Table of Attributes The following table provides a guide to which attributes may be found in which kinds of packets, and in what quantity. Request Accept Reject Challenge Attribute 1 0 0 0 User-Name 0-1 0 0 0 User-Password [1] 0-1 0 0 0 CHAP-Password [1] 0-1 0 0 0 NAS-IP-Address [2] 1 0 0 0 NAS-Port 0-1 0-1 0 0 Service-Type 0-1 0-1 0 0 Framed-Protocol 0-1 0-1 0 0 Framed-IP-Address 0-1 0-1 0 0 Framed-IP-Netmask 0 0-1 0 0 Framed-Routing 0 0+ 0 0 Filter-Id 0 0-1 0 0 Framed-MTU 0+ 0+ 0 0 Framed-Compression 0+ 0+ 0 0 Login-IP-Host 0 0-1 0 0 Login-Service 0 0-1 0 0 Login-Port 0 0+ 0+ 0+ Reply-Message 0-1 0-1 0 0 Login-Callback-Number 0 0-1 0 0 Framed-Callback-Id 0 0+ 0 0 Framed-Route 0 0-1 0 0 Framed-IPX-Network 0-1 0-1 0 0-1 State 0 0-1 0 0 Class 0+ 0+ 0 0+ Vendor-Specific 0 0-1 0 0-1 Session-Timeout 0 0-1 0 0-1 Idle-Timeout 0 0-1 0 0 Termination-Action 0-1 0 0 0 Client-Port-DNIS 0-1 0 0 0 Caller-Id 0-1 0 0 0 NAS-Identifier [2] 0+ 0+ 0+ 0+ Proxy-State 0 0-1 0 0 Login-LAT-Service 0 0-1 0 0 Login-LAT-Node 0 0-1 0 0 Login-LAT-Group 0 0-1 0 0 Framed-AppleTalk-Link 0 0+ 0 0 Framed-AppleTalk-Network 0 0-1 0 0 Framed-AppleTalk-Zone [1] An Access-Request MUST contain either a User-Password or a CHAP-Password, and MUST NOT contain both. Rigney, et alia expires in six months [Page 50] DRAFT RADIUS Authentication May 1995 [2] An Access-Request MUST contain either a NAS-IP-Address or a NAS- Identifier, and it is all right (but not recommended) for it to contain both. The following table defines the meaning of the above table entries. 0 This attribute MUST NOT be present in packet. 0+ Zero or more instances of this attribute MAY be present in packet. 0-1 Zero or one instance of this attribute MAY be present in packet. 1 Exactly one instance of this attribute MUST be present in packet. Rigney, et alia expires in six months [Page 51] DRAFT RADIUS Authentication May 1995 Security Considerations Security issues are the primary topic of this document. In practice, within or associated with each RADIUS server, there is a database which associates "user" names with authentication information ("secrets"). It is not anticipated that a particular named user would be authenticated by multiple methods. This would make the user vulnerable to attacks which negotiate the least secure method from among a set (such as PAP rather than CHAP). Instead, for each named user there should be an indication of exactly one method used to authenticate that user name. If a user needs to make use of different authentication methods under different circumstances, then distinct user names SHOULD be employed, each of which identifies exactly one authentication method. Passwords and other secrets should be stored at the respective ends such that access to them is as limited as possible. Ideally, the secrets should only be accessible to the process requiring access in order to perform the authentication. The secrets should be distributed with a mechanism that limits the number of entities that handle (and thus gain knowledge of) the secret. Ideally, no unauthorized person should ever gain knowledge of the secrets. It is possible to achieve this with SNMP Security Protocols [4], but such a mechanism is outside the scope of this specification. Other distribution methods are currently undergoing research and experimentation. The SNMP Security document [4] also has an excellent overview of threats to network protocols. Rigney, et alia expires in six months [Page 52] DRAFT RADIUS Authentication May 1995 References [1] Postel, J., "User Datagram Protocol", RFC 768, USC/Information Sciences Institute, August 1980. [2] Reynolds, J., and J. Postel, "Assigned Numbers", RFC 1700, USC/Information Sciences Institute, October 1994. [3] Rivest, R., and S. Dusse, "The MD5 Message-Digest Algorithm", MIT Laboratory for Computer Science and RSA Data Security, Inc., RFC 1321, April 1992. [4] Galvin, J., McCloghrie, K., and J. Davin, "SNMP Security Protocols", Trusted Information Systems, Inc., Hughes LAN Systems, Inc., MIT Laboratory for Computer Science, RFC 1352, July 1992. Acknowledgments RADIUS was originally developed by Livingston Enterprises for their PortMaster series of Network Access Servers. Rigney, et alia expires in six months [Page 53] DRAFT RADIUS Authentication May 1995 Chair's Address The working group can be contacted via the current chair: [TBD] Author's Address Questions about this memo can also be directed to: Carl Rigney Livingston Enterprises 6920 Koll Center Parkway, Suite 220 Pleasanton, California 94566 EMail: cdr@livingston.com Allan C. Rubens Merit Network, Inc. 4251 Plymouth Road Ann Arbor, Michigan 48105-2785 EMail: acr@merit.edu William Allen Simpson Daydreamer Computer Systems Consulting Services 1384 Fontaine Madison Heights, Michigan 48071 EMail: Bill.Simpson@um.cc.umich.edu Steve Willens Livingston Enterprises 6920 Koll Center Parkway, Suite 220 Pleasanton, California 94566 EMail: steve@livingston.com Rigney, et alia expires in six months [Page 54]