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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 12 RFC 6614

RADIUS Extensions Working Group                                S. Winter
Internet-Draft                                                   RESTENA
Intended status: Experimental                                M. McCauley
Expires: February 23, 2009                                           OSC
                                                               S. Venaas
                                                                 UNINETT
                                                             K. Wierenga
                                                                   Cisco
                                                         August 22, 2008


              TLS encryption for RADIUS over TCP (RadSec)
                      draft-ietf-radext-radsec-01

Status of This Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
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   This Internet-Draft will expire on February 23, 2009.

Abstract

   This document specifies security on the transport layer (TLS) for the
   RADIUS protocol [RFC2865] when transmitted over TCP
   [I-D.dekok-radext-tcp-transport].  This enables dynamic trust
   relationships between RADIUS servers.






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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  3
     1.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Normative: Transport Layer Security for RADIUS over TCP  . . .  4
     2.1.  TCP port and packet types  . . . . . . . . . . . . . . . .  4
     2.2.  Connection Setup . . . . . . . . . . . . . . . . . . . . .  4
     2.3.  RADIUS Datagrams . . . . . . . . . . . . . . . . . . . . .  5
   3.  Informative: Design Decisions  . . . . . . . . . . . . . . . .  6
     3.1.  X.509 Certificate Considerations . . . . . . . . . . . . .  6
     3.2.  Ciphersuites and Compression Negotiation Considerations  .  8
     3.3.  RADIUS Datagram Considerations . . . . . . . . . . . . . .  8
   4.  Diameter Compatibility . . . . . . . . . . . . . . . . . . . .  9
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     8.1.  Informative References . . . . . . . . . . . . . . . . . . 10
     8.2.  Normative References . . . . . . . . . . . . . . . . . . . 11
   Appendix A.  DNS NAPTR Peer Discovery  . . . . . . . . . . . . . . 12
   Appendix B.  Implementation Overview: Radiator . . . . . . . . . . 13
   Appendix C.  Implementation Overview: radsecproxy  . . . . . . . . 14




























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1.  Introduction

   The RADIUS protocol [RFC2865] is a widely deployed authentication and
   authorisation protocol.  The supplementary RADIUS Accounting
   specification [RFC2866] also provides accounting mechanisms, thus
   delivering a full AAA solution.  However, RADIUS is experiencing
   several shortcomings, such as its dependency on the unreliable
   transport protocol UDP and the lack of security for large parts of
   its packet payload.  RADIUS security is based on the MD5 algorithm,
   which has been proven to be insecure.

   The main focus of RadSec is to provide a means to secure the
   communication between RADIUS/TCP peers on the transport layer.  The
   most important use of RadSec lies in roaming environments where
   RADIUS packets need to be transferred through different
   administrative domains and untrusted, potentially hostile networks.
   An example for a world-wide roaming environment that uses RadSec to
   secure communication is "eduroam", see [eduroam].

   There are multiple known attacks on the MD5 algorithm which is used
   in RADIUS to provide integrity protection and a limited
   confidentiality protection.  RadSec wraps the entire RADIUS packet
   payload into a TLS stream and thus mitigates the risk of attacks on
   MD5.

   Because of the static trust establishment between RADIUS peers (IP
   address and shared secret) the only scalable way of creating a
   massive deployment of RADIUS-servers under control by different
   administrative entities is to introduce some form of a proxy chain to
   route the access requests to their home server.  This creates a lot
   of overhead in terms of possible points of failure, longer
   transmission times as well as middleboxes through which
   authentication traffic flows.  These middleboxes may learn privacy-
   relevant data while forwarding requests.  The new features in RadSec
   obsolete the use of IP addresses and shared MD5 secrets to identify
   other peers and thus allow the dynamic establishment of connections
   to peers that are not previously configured, and thus makes it
   possible to avoid intermediate aggregation proxies.  The definition
   of lookup mechanisms is out of scope of this document, but an
   implementation of a DNS NAPTR lookup based mechanism exists and is
   described as an example lookup mechanism in Appendix A.

1.1.  Requirements Language

   In this document, several words are used to signify the requirements
   of the specification.  The key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" in this document are to be interpreted as described in



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   [RFC2119].

1.2.  Terminology

   RadSec node: a RadSec client or server

   RadSec Client: a RadSec instance which initiates a new connection.

   RadSec Server: a RadSec instance which listens on a RadSec port and
   accepts new connections

2.  Normative: Transport Layer Security for RADIUS over TCP

2.1.  TCP port and packet types

   The default destination port number for RadSec is TCP/2083.  There
   are no separate ports for authentication, accounting and dynamic
   authorisation changes.  The source port is arbitrary.

2.2.  Connection Setup

   RadSec nodes

   1.  establish TCP connections as per [I-D.dekok-radext-tcp-transport]

   2.  negotiate TLS sessions according to [RFC5246] or its predecessor
       TLS 1.1.  The following restrictions apply:

       *  When using X.509 certificates, RadSec servers SHOULD indicate
          their acceptable Certification Authorities as per section
          7.4.4 of [RFC5246] (see Section 3.1 (1) )

       *  When using X.509 certificates, the TLS Extension "Trusted CA
          Indication" from [RFC5246] or its TLS 1.1 predecessor SHOULD
          be used to indicate trusted CAs for the client (see
          Section 3.1 (2) )

       *  When using X.509 certificates, certificate validation is
          performed as per [RFC5280] or its TLS 1.1 predecessor.  The
          client MAY perform additional checks to accomodate for
          different trust models.

       *  The client MUST NOT negotiate cipher suites which only provide
          integrity protection.

       *  The cipher suite TLS_RSA_WITH_3DES_EDE_CBC_SHA MUST be
          supported.




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       *  The cipher suites TLS_RSA_WITH_AES_128_CBC_SHA and
          TLS_RSA_WITH_RC4_128_SHA SHOULD be supported. (see Section 3.2
          (1) )

   3.  start exchanging RADIUS datagrams.  Note Section 3.3 (1) ).  The
       shared secret to compute the (obsolete) MD5 integrity checks and
       attribute encryption MUST be "radsec" (see Section 3.3 (2) ).

2.3.  RADIUS Datagrams

   Authentication, Accounting and Authorization packets are sent
   according to the following rules:

   RadSec clients handle the following packet types from [RFC2865],
   [RFC2866], [RFC5176] on the connection they initiated (see
   Section 3.3 (3) and (4) ):

   o  send Access-Request

   o  send Accounting-Request

   o  send Status-Server

   o  send Disconnect-ACK

   o  send Disconnect-NAK

   o  send CoA-ACK

   o  send CoA-NAK

   o  receive Access-Challenge

   o  receive Access-Accept

   o  receive Access-Reject

   o  receive Accounting-Response

   o  receive Disconnect-Request

   o  receive CoA-Request

   RadSec servers handle the following packet types from [RFC2865],
   [RFC2866], [RFC5176] on the connections they serve to clients:

   o  receive Access-Request




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   o  receive Accounting-Request

   o  receive Status-Server

   o  receive Disconnect-ACK

   o  receive Disconnect-NAK

   o  receive CoA-ACK

   o  receive CoA-NAK

   o  send Access-Challenge

   o  send Access-Accept

   o  send Access-Reject

   o  send Accounting-Response

   o  send Disconnect-Request

   o  send CoA-Request

3.  Informative: Design Decisions

   This section explains the design decisions that led to the rules
   defined in the previous section.

3.1.  X.509 Certificate Considerations

   (1) If a RadSec client is in possession of multiple certificates from
   different CAs (i.e. is part of multiple roaming consortia) and
   dynamic discovery is used, the discovery mechanism possibly does not
   yield sufficient information to identify the consortium uniquely
   (e.g.  DNS discovery).  Subsequently, the client may not know by
   itself which client certificate to use for the TLS handshake.  Then
   it is necessary to for the server to signal which consortium it
   belongs to, and which certificates it expects.  If there is no risk
   of confusing multiple roaming consortia, providing this information
   in the handshake is not crucial.

   (2) If a RadSec server is in possession of multiple certificates from
   different CAs (i.e. is part of multiple roaming consortia), it will
   need to select one of its certificates to present to the RadSec
   client.  If the client sends the Trusted CA Indication, this hint can
   make the server select the appropriate certificate and prevent a
   handshake failure.  Omitting this indication makes it impossible to



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   deterministically select the right certificate in this case.  If
   there is no risk of confusing multiple roaming consortia, providing
   this indication in the handshake is not crucial.

   (3) When using X.509 certificate validation, peer validation always
   includes a check on whether the DNS name or the IP address of the
   server that is contacted matches its certificate.  When a RadSec peer
   establishes a new connection (acts as a client) to another peer, the
   following rules of precedence are used during validation:

   o  If the client expects a certain fully qualified domain name (FQDN)
      and the presented certificate contains both at least one instance
      of the subjectAltName field with type dNSName and a Common Name,
      then the certificate is considered a match if any one of those
      subjectAltName fields matches the expected FQDN.  The Common Name
      field is not evaluated in this case.

   o  If the client expects a certain fully qualified domain name (FQDN)
      and the presented certificate does not contain any subjectAltName
      field with type dNSName, then the certificate is considered a
      match if the Common Name field matches the expected FQDN.

   o  If the client expects a certain IP address and the presented
      certificate contains both at least one instance of the
      subjectAltName field with type iPAddr and a Common Name, then the
      certificate is considered a match if any one of those
      subjectAltName fields matches the expected IP address.  The Common
      Name field is not evaluated in this case.

   o  If the client expects a certain IP address and the presented
      certificate does not contain any subjectAltName field with type
      iPAddr, then the certificate is considered a match if the Common
      Name field matches the expected IP address.

   (4) If dynamic peer resolution is used, the above verification steps
   may not be sufficient to ensure that a connecting peer is authorised
   to perform user authentications.  In these cases, the trust fabric
   cannot depend on peer authentication methods like DNSSEC to identify
   RadSec nodes.  The RadSec nodes also need to be properly authorised.
   Operators of a RadSec infrastructure should define their own
   authorisation trust model and apply this model to the certificates
   after they have passed the standard validity checks above.  Current
   RadSec implementations offer varying degrees of versatility for
   defining criteria which certificates to accept.







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3.2.  Ciphersuites and Compression Negotiation Considerations

   RadSec implementations need not necessarily support all TLS
   ciphersuites listed in [RFC5246]. Not all TLS ciphersuites
   are supported by available TLS tool kits and licenses may be required
   in some cases.  The existing implementations of RadSec use OpenSSL as
   cryptographic backend, which supports all of the ciphersuites listed
   in the rules in the normative section.

   The TLS cphersuite TLS_RSA_WITH_3DES_EDE_CBC_SHA is mandatory-to-
   implement according to [RFC5246] and thus has to be supported by
   RadSec nodes.

   The two other ciphersuites in the normative section
   (TLS_RSA_WITH_RC4_128_SHA and TLS_RSA_WITH_AES_128_CBC_SHA) are
   widely implemented in TLS toolkits and are considered good practice
   to implement.

   TLS also supports compression.  Compression is an optional
   feature. During the RadSec conversation the client and server may
   negotiate compression, but must continue the conversation even if the
   other peer rejects compression.

3.3.  RADIUS Datagram Considerations

   (1) After the TLS session is established, RADIUS packet payloads are
   exchanged over the encrypted TLS tunnel.  In plain RADIUS, the packet
   size can be determined by evaluating the size of the datagram that
   arrived.  Due to the stream nature of TCP and TLS, this does not hold
   true for RadSec packet exchange.  Instead, packet boundaries of
   RADIUS packets that arrive in the stream are calculated by evaluating
   the packet's Length field.  Special care needs to be taken on the
   packet sender side that the value of the Length field is indeed
   correct before sending it over the TLS tunnel, because incorrect
   packet lengths can no longer be detected by a differing datagram
   boundary.

   (2) Within RADIUS [RFC2865], a shared secret is used for hiding
   of attributes such as User-Password, as well as in computation of
   the Response Authenticator.  In RADIUS accounting [RFC2866], the
   shared secret is used in computation of both the Request
   Authenticator and the Response Authenticator.  Since TLS provides
   integrity protection and encryption sufficient to substitute for
   RADIUS application-layer security, it is not necessary to configure a
   RADIUS shared secret.  The use of a fixed string for the obsolete
   shared secret eliminates possible node misconfigurations.

   (3) RADIUS [RFC2865] uses different UDP ports for authentication,



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   accounting and dynamic authorisation changes.  RadSec allocates a
   single port for all RADIUS packet types.  Also in RadSec, the notion
   of a client which sends authentication requests and processes replies
   associated with it's users' sessions and the notion of a server which
   receives requests, processes them and sends the appropriate replies
   is to be preserved.  The normative rules about acceptable packet
   types for clients and servers mirror the packet flow behaviour from
   RADIUS.

   (4) RADIUS [RFC2865] used negative ICMP responses to a newly
   allocated UDP port to signal that a peer RADIUS server does not
   support reception and processing of the packet types in [RFC5176].
   These packet types are listed as to be received in RadSec
   implementations.  Note well: it is not required for an implementation
   to actually process these packet types.  It is sufficient that upon
   receiving such a packet, an unconditional NAK is sent back to
   indicate that the action is not supported.

4.  Diameter Compatibility

   Since RadSec is only a new transport profile for RADIUS,
   compatibility of RadSec - Diameter [RFC3588] vs. RADIUS [RFC2865] -
   Diameter [RFC3588] is identical.  The considerations regarding
   payload size in [I-D.dekok-radext-tcp-transport] apply.

5.  Security Considerations

   The computational resources to establish a TLS tunnel are
   significantly higher than simply sending mostly unencrypted UDP
   datagrams.  Therefore, clients connecting to a RadSec node will more
   easily create high load conditions and a malicious client might
   create a Denial-of-Service attack more easily.

   In the case of dynamic peer discovery, a RadSec node needs to be able
   to accept connections from a large, not previously known, group of
   hosts, possibly the whole internet.  In this case, the server's
   RadSec port can not be protected from unauthorised connection
   attempts with measures on the network layer, i.e. access lists and
   firewalls.  This opens more attack vectors for Distributed Denial of
   Service attacks, just like any other service that is supposed to
   serve arbitrary clients (like for example web servers).

   Some TLS ciphersuites only provide integrity validation of their
   payload, and provide no encryption.  This specification forbids the
   use of such ciphersuites.  Since the RADIUS payload's shared secret
   is fixed and well-known, failure to comply with this requirement will
   expose the entire datagram payload in plain text, including User-
   Password, to intermediate IP nodes.



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6.  IANA Considerations

   This document has no actions for IANA.  The TCP port 2083 was already
   previously assigned by IANA for RadSec.  No new RADIUS attributes or
   packet codes are defined.

7.  Acknowledgements

   RadSec version 1 was first implemented by Open Systems Consultants,
   Currumbin Waters, Australia, for their "Radiator" RADIUS server
   product (see [radsec-whitepaper]).

   Funding and input for the development of this Internet Draft was
   provided by the European Commission co-funded project "GEANT2"
   [geant2] and further feedback was provided by the TERENA Task Force
   Mobility [terena].

8.  References

8.1.  Informative References

   [RFC2119]                         Bradner, S., "Key words for use in
                                     RFCs to Indicate Requirement
                                     Levels", BCP 14, RFC 2119,
                                     March 1997.

   [radsec-whitepaper]               Open System Consultants, "RadSec -
                                     a secure, reliable RADIUS
                                     Protocol", May 2005, <http://
                                     www.open.com.au/radiator/
                                     radsec-whitepaper.pdf>.

   [radiator-manual]                 Open System Consultants, "Radiator
                                     Radius Server - Installation and
                                     Reference Manual", 2006, <http://
                                     www.open.com.au/radiator/ref.html>.

   [radsecproxy-impl]                Venaas, S., "radsecproxy Project
                                     Homepage", 2007, <http://
                                     software.uninett.no/radsecproxy/>.

   [eduroam]                         Trans-European Research and
                                     Education Networking Association,
                                     "eduroam Homepage", 2007,
                                     <http://www.eduroam.org/>.

   [geant2]                          Delivery of Advanced Network
                                     Technology to Europe, "European



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                                     Commission Information Society and
                                     Media: GEANT2", 2008,
                                     <http://www.geant2.net/>.

   [terena]                          TERENA, "Trans-European Research
                                     and Education Networking
                                     Association", 2008,
                                     <http://www.terena.org/>.

8.2.  Normative References

   [RFC2865]                         Rigney, C., Willens, S., Rubens,
                                     A., and W. Simpson, "Remote
                                     Authentication Dial In User Service
                                     (RADIUS)", RFC 2865, June 2000.

   [RFC2866]                         Rigney, C., "RADIUS Accounting",
                                     RFC 2866, June 2000.

   [RFC5280]                         Cooper, D., Santesson, S., Farrell,
                                     S., Boeyen, S., Housley, R., and W.
                                     Polk, "Internet X.509 Public Key
                                     Infrastructure Certificate and
                                     Certificate Revocation List (CRL)
                                     Profile", RFC 5280, May 2008.

   [RFC5176]                         Chiba, M., Dommety, G., Eklund, M.,
                                     Mitton, D., and B. Aboba, "Dynamic
                                     Authorization Extensions to Remote
                                     Authentication Dial In User Service
                                     (RADIUS)", RFC 5176, January 2008.

   [RFC3588]                         Calhoun, P., Loughney, J., Guttman,
                                     E., Zorn, G., and J. Arkko,
                                     "Diameter Base Protocol", RFC 3588,
                                     September 2003.

   [RFC5246]                         Dierks, T. and E. Rescorla, "The
                                     Transport Layer Security (TLS)
                                     Protocol Version 1.2", RFC 5246,
                                     August 2008.

   [I-D.dekok-radext-tcp-transport]  DeKok, A., "RADIUS Over TCP",
                                     draft-dekok-radext-tcp-transport-00
                                     (work in progress), July 2008.






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Appendix A.  DNS NAPTR Peer Discovery

   The following text is quoted from the file goodies/dnsroam.cfg in the
   Radiator distribution; further documentation of the <AuthBy DNSROAM>
   feature in Radiator can be found at [radiator-manual].  It describes
   an algorithm to retrieve the RadSec route information from the global
   DNS using NAPTR and SRV records.  The input of the algorithm is the
   realm part of the user name.

   The following algorithm is used to discover a target server from a
   Realm using DNS:

   1.  Look for NAPTR records for the Realm.

   2.  For each NAPTR found record, examine the Service field and use
       that to determine the transport protocol and TLS requirements for
       the server.  The Service field starts with 'AAA' for insecure and
       'AAAS' for TLS secured.  The Service field contains '+RADSECS'
       for RadSec over SCTP, '+RADSECT' for RadSec over TCP or '+RADIUS'
       for RADIUS protocol over UDP.  The most common Service field you
       will see will be 'AAAS+RADSECT' for TLS secured RadSec over TCP.

   3.

       A.  If the NAPTR has the 'S' flag, look for SRV records for the
           name.  For each SRV record found, note the Port number and
           then look for A and AAAA records corresponding to the name in
           the SRV record.

       B.  If the NAPTR has the 'A' flag, look for a A and AAAA records
           for the name.

   4.  If no NAPTR records are found, look for A and AAAA records based
       directly on the realm name.  For example, if the realm is
       'examplerealm.edu', it looks for records such as
       '_radsec._tcp.examplerealm.edu', '_radsec._sctp.examplerealm.edu'
       and '_radius._udp.examplerealm.edu',

   5.  All A and AAAA records found are ordered according to their Order
       and Preference fields.  The most preferable server address is
       used as the target server address, along with any other server
       attributes discovered from DNS.  If no SRV record was found for
       the address, the DNSROAM configured Port is used.

   For example, if the User-Name realm was 'examplerealm.edu', and DNS
   contained the following records:





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      examplerealm.edu.  IN NAPTR 50 50 "s" "AAAS+RADSECT" ""
      _radsec._tcp.examplerealm.edu.

      _radsec._tcp.examplerealm.edu.  IN SRV 0 10 2083
      radsec.examplerealm.edu.

      radsec.examplerealm.edu.  IN AAAA 2001::202:44ff:fe0a:f704

   Then the target selected would be a RadSec server on port 2083 at
   IPv6 address 2001::202:44ff:fe0a:f704.  The connection would be made
   over TCP/IP, and TLS encryption would be used.  This complete
   specification of the realm is the most flexible and is recommended.

Appendix B.  Implementation Overview: Radiator

   Radiator implements the RadSec protocol for proxying requests with
   the <Authby RADSEC> and <ServerRADSEC> clauses in the Radiator
   configuration file.

   The <AuthBy RADSEC> clause defines a RadSec client, and causes
   Radiator to send RADIUS requests to the configured RadSec server
   using the RadSec protocol.

   The <ServerRADSEC> clause defines a RadSec server, and causes
   Radiator to listen on the configured port and address(es) for
   connections from <Authby RADSEC> clients.  When an <Authby RADSEC>
   client connects to a <ServerRADSEC> server, the client sends RADIUS
   requests through the stream to the server.  The server then services
   the request in the same was as if the request had been received from
   a conventional UDP RADIUS client.

   Radiator is compliant to version 2 of RadSec if the following options
   are used:

      <AuthBy RADSEC>

      *  Protocol tcp

      *  UseTLS

      *  TLS_CertificateFile

      <ServerRADSEC>

      *  Protocol tcp

      *  UseTLS




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      *  TLS_RequireClientCert

   As of Radiator 3.15, the default shared secret for RadSec connections
   is "mysecret" (without quotes).  The implementation uses TCP
   keepalive socket options, but does not send Status-Server packets.
   Once established, TLS connections are kept open throughout the server
   instance lifetime.

Appendix C.  Implementation Overview: radsecproxy

   The RADIUS proxy named radsecproxy was written in order to allow use
   of RadSec in current RADIUS deployments.  This is a generic proxy
   that supports any number and combination of clients and servers,
   supporting RADIUS over UDP and RadSec.  The main idea is that it can
   be used on the same host as a non-RadSec client or server to ensure
   RadSec is used on the wire, however as a generic proxy it can be used
   in other circumstances as well.

   The configuration file consists of client and server clauses, where
   there is one such clause for each client or server.  In such a clause
   one specifies either "type tls" or "type udp" for RadSec or UDP
   transport.  For RadSec the default shared secret "mysecret" (without
   quotes), the same as Radiator, is used.  A secret may be specified by
   putting say "secret somesharedsecret" inside a client or server
   clause.

   In order to use TLS for clients and/or servers, one must also specify
   where to locate CA certificates, as well as certificate and key for
   the client or server.  This is done in a TLS clause.  There may be
   one or several TLS clauses.  A client or server clause may reference
   a particular TLS clause, or just use a default one.  One use for
   multiple TLS clauses may be to present one certificate to clients and
   another to servers.

   If any RadSec (TLS) clients are configured, the proxy will at startup
   listen on port 2083, as assigned by IANA for the OSC RadSec
   implementation.  An alternative port may be specified.  When a client
   connects, the client certificate will be verified, including checking
   that the configured FQDN or IP address matches what is in the
   certificate.  Requests coming from a RadSec client are treated
   exactly like requests from UDP clients.

   The proxy will at startup try to establish a TLS connection to each
   (if any) of the configured RadSec (TLS) servers.  If it fails to
   connect to a server, it will retry regularly.  There is some back-off
   where it will retry quickly at first, and with longer intervals
   later.  If a connection to a server goes down it will also start
   retrying regularly.  When setting up the TLS connection, the server



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   certificate will be verified, including checking that the configured
   FQDN or IP address matches what is in the certificate.  Requests are
   sent to a RadSec server just like they would to a UDP server.

   The proxy supports Status-Server messages.  They are only sent to a
   server if enabled for that particular server.  Status-Server requests
   are always responded to.

   This RadSec implementation has been successfully tested together with
   Radiator.  It is a freely available open-source implementation.  For
   source code and documentation, see [radsecproxy-impl].

Authors' Addresses

   Stefan Winter
   Fondation RESTENA
   6, rue Richard Coudenhove-Kalergi
   Luxembourg  1359
   LUXEMBOURG

   Phone: +352 424409 1
   Fax:   +352 422473
   EMail: stefan.winter@restena.lu
   URI:   http://www.restena.lu.


   Mike McCauley
   Open Systems Consultants
   9 Bulbul Place
   Currumbin Waters  QLD 4223
   AUSTRALIA

   Phone: +61 7 5598 7474
   Fax:   +61 7 5598 7070
   EMail: mikem@open.com.au
   URI:   http://www.open.com.au.















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   Stig Venaas
   UNINETT
   Abels gate 5 - Teknobyen
   Trondheim  7465
   NORWAY

   Phone: +47 73 55 79 00
   Fax:   +47 73 55 79 01
   EMail: stig.venaas@uninett.no
   URI:   http://www.uninett.no.


   Klaas Wierenga
   Cisco Systems International BV
   Haarlerbergweg 13-19
   Amsterdam  1101 CH
   The Netherlands

   Phone: +31 (0)20 3571752
   Fax:
   EMail: kwiereng@cisco.com
   URI:   http://www.cisco.com.





























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Full Copyright Statement

   Copyright (C) The IETF Trust (2008).

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Acknowledgement

   This document was produced using xml2rfc v1.33 (of
   http://xml.resource.org/) from a source in RFC-2629 XML format.







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