5. Abuse Prevention and Incident Handling Since the eduroam service is a confederation of autonomous networks, there is little justification for transferring accounting information from the Service Provider to any other (in general) or to the Identity Provider of the user (in particular). Accounting in eduroam is therefore considered to be a local matter of the Service Provider. The eduroam compliance statement [eduroam-compliance] in fact specifies that accounting traffic [RFC5280] SHOULD NOT be forwarded. The static routing infrastructure of eduroam acts as a filtering system blocking accounting traffic from misconfigured local RADIUS servers. Proxy servers are configured to terminate accounting request traffic by answering to Accounting-Requests with an Accounting-Response in order to prevent the retransmission of orphaned Accounting-Request messages. With dynamic discovery, Identity Providers that are discoverable via DNS will need to apply these filtering measures themselves. This is an increase in complexity of the Identity Provider RADIUS configuration. Roaming creates accountability problems, as identified by [RFC4372] (Chargeable User Identity). Since the NAS can only see the (likely anonymous) outer identity of the user, it is impossible to correlate usage with a specific user (who may use multiple devices). A NAS that supports [RFC4372] can request the Chargeable-User-Identity and, if supplied by the authenticating RADIUS server in the Access-Accept message, add this value to corresponding Access-Request packets. While eduroam does not have any charging mechanisms, it may still be desirable to identify traffic originating from one particular user. One of the reasons is to prevent abuse of guest access by users living near university campuses. Chargeable User Identity (see Section 5.3) supplies the perfect answer to this problem; however, at the time of writing, to our knowledge, only one hardware vendor (Meru Networks) implements RFC 4372 on their access points. For all other vendors, requesting the Chargeable-User-Identity attribute needs to happen on the RADIUS server to which the access point is connected to. FreeRADIUS supports this ability in the latest distribution, and Radiator can be retrofitted to do the same. 5.1. Incident Handling 10 years of experience with eduroam have not exposed any serious incident. This may be taken as evidence for proper security design as well as suggest that users' awareness that they are identifiable acts as an effective deterrent. It could of course also mean that eduroam operations lack the proper tools or insight into the actual use and potential abuse of the service. In any case, many of the
attack vectors that exist in open networks or networks where access control is based on shared secrets are not present, arguably leading to a much more secure system. Below is a discussion of countermeasures that are taken in eduroam. The European eduroam Policy Service Definition [eduroam-service-definition], as an example, describes incident scenarios and actions to be taken; in this document, we present the relevant technical issues. The initial implementation has been lacking reliable tools for an SP to make its own decision or for an IdP to introduce a conditional rule applying only to a given SP. The introduction of support for Operator-Name and Chargeable-User-Identity (see Section 5.3) to eduroam makes both of these scenarios possible. 5.1.1. Blocking Users on the SP Side The first action in the case of an incident is to block the user's access to eduroam at the Service Provider. Since the roaming user's true identity is likely hidden behind an anonymous/fake outer identity, the Service Provider can only rely on the realm of the user and his MAC address; if the Identity Provider has already sent a Chargeable-User-Identity (see Section 5.3 for details), then this extra information can be used to identify the user more reliably. A first attempt at the SP side may be to block based on the MAC address or outer identity. This blocking can be executed before the EAP authentication occurs -- typically in the first datagram, acting on the RADIUS attributes EAP-Message/EAP-Response/Identity and Calling-Station-ID. The datagram can either be dropped (supplicant notices a time-out) or replied to with a RADIUS Access-Reject containing an EAP-Failure. Since malicious users can change both their MAC addresses and the local part of their outer identity between connection attempts, this first attempt is not sufficient to lock out a determined user. As a second measure, the SP can let the EAP authentication proceed as normal, and verify whether the final Access-Accept response from the RADIUS server contains a Chargeable-User-Identity (CUI). If so, the SP RADIUS server can be configured to turn all future Access-Accepts for this CUI into an Access-Reject/EAP-Failure. This measure is effective and efficient: it locks out exactly the one user that is supposed to be locked out, and it has no side-effects on other users, even from the same realm.
If the EAP authentication does not reveal a CUI, the SP cannot reliably determine the user in question. The only reliable information to act upon is then the realm portion of the outer identity of the user. The SP will need to resort to blocking the entire realm that the offending user belongs to. This is effective, but not efficient: it locks out the user in question, but has a DoS side-effect on all other visiting users from the same realm. In the absence of a CUI handle, SPs that are not willing to take the drastic step of blocking an entire realm will be forced to contact the Identity Provider in question and demand that the user be blocked at the IdP side. This involves human interaction between SP and IdP and is not possible in real-time. 5.1.2. Blocking Users on the IdP Side The IdP has the power to disable a user account altogether, thus blocking this user from accessing eduroam in all sites. If blocking the user is done due a request of an SP (as per the previous section), there may be a more fine-grained possibility to block access to a specific SP -- if the SP in question sends the Operator- Name attribute along with his Access-Requests (see Section 5.2 for details). If the IdP decides to block the user globally, this is typically done by treating the login attempt as if the credentials were wrong: the entire EAP conversation needs to be executed to the point where the true inner identity is revealed (before that, the IdP does not know yet which user is attempting to authenticate). This typically coincides with the point in time where credentials are exchanged. Instead of, or in addition to, checking the credential for validity, the Identity Provider also checks whether the user's account is (still) eligible for eduroam use and will return an Access-Reject/ EAP-Failure if not. There may well be cases where opinions between the SP desiring a user lockout and the IdP of the user differ. For example, an SP might consider massive amounts of up-/downloads with file sharing protocols unacceptable as per local policy, and desire blocking of users that create too much traffic -- but the IdP does not take offense on such actions and would not want to lock his user out of eduroam globally because of this one SP's opinion. In the absence of the Operator-Name attribute, there is no way to apply a login restriction only for a given SP and not eduroam as a whole; eduroam eligibility is an all-or-nothing decision for the IdP.
If the Operator-Name attribute is present, the IdP can use this information to fail the authentication attempt only if the attempt originated from SPs that desire such blocking. Even though the Operator-Name attribute is available from the first RADIUS Access- Request datagram onwards, the EAP authentication needs to be carried out until the true inner identity is known just as in the global blocking case above. The Operator-Name is simply an additional piece of information that the IdP can use to make its decision. 5.1.3. Communicating Account Blocking to the End User The measures described in Sections 5.1.1 and 5.1.2 alter the EAP conversation. They either create a premature rejection or timeout at the start of the conversation or change the outcome of the authentication attempt at the very end of the conversation. On the supplicant side, these alterations are indistinguishable from an infrastructure failure: a premature rejection or timeout could be due to a RADIUS server being unresponsive, and a rejection at the end of the conversation could be either user error (wrong password) or server error (credential lookup failed). For the supplicant, it is thus difficult to communicate a meaningful error to the user. The newly specified EAP type TEAP, Tunnel Extensible Authentication Protocol [RFC7170], has a means to transport fine-grained error reason codes to the supplicant; this has the potential to improve the situation in the future. The EAP protocol foresees one mechanism to provide such user- interactive communication: the EAP state machine contains states that allow user-visible communication. An extra round of EAP-Request/ Notification and the corresponding acknowledgement can be injected before the final EAP-Failure. However, anecdotal evidence suggests that supplicants typically do not implement this part of the EAP state machine at all. One supplicant is reported to support it, but only logs the contents of the notification in a log file -- which is not at all helpful for the end user. The discovery of reasons and scope of account blocking are thus left as an out-of-band action. The eduroam user support process requires that users with authentication problems contact their Identity Provider as a first measure (via unspecified means, e.g., they could phone their IdP or send an email via a 3G backup link). If the Identity Provider is the one that blocked their access, the user will immediately be informed by them. If the reason for blocking is at the SP side, the Identity Provider will instead inform the user that
the account is in working order and that the user needs to contact the SP IT support to get further insight. In that case, that SP-side IT support will notify the users about the reasons for blocking. 5.2. Operator Name The Operator-Name attribute is defined in [RFC5580] as a means of unique identification of the access site. The Proxy infrastructure of eduroam makes it impossible for home sites to tell where their users roam. While this may be seen as a positive aspect enhancing user's privacy, it also makes user support, roaming statistics, and blocking offending user's access to eduroam significantly harder. Sites participating in eduroam are encouraged to add the Operator- Name attribute using the REALM namespace, i.e., sending a realm name under control of the given site. The introduction of Operator-Name in eduroam has led to the identification of one operational problem -- the identifier 126 assigned to this attribute has been previously used by some vendors for their specific purposes and has been included in attribute dictionaries of several RADIUS server distributions. Since the syntax of this hijacked attribute had been set to Integer, this introduces a syntax clash with the RFC definition (which defines it as Text). Operational tests in eduroam have shown that servers using the Integer syntax for attribute 126 may either truncate the value to 4 octets or even drop the entire RADIUS packet (thus making authentication impossible). The eduroam monitoring and eduroam test tools try to locate problematic sites. Section 2.8 of [RFC6929] clarifies the handling of these packets. When a Service Provider sends its Operator-Name value, it creates a possibility for the home sites to set up conditional blocking rules, depriving certain users of access to selected sites. Such action will cause much less concern than blocking users from all of eduroam. In eduroam, the Operator Name is also used for the generation of Chargeable User Identity values. The addition of Operator-Name is a straightforward configuration of the RADIUS server and may be easily introduced on a large scale.
5.3. Chargeable User Identity The Chargeable-User-Identity (CUI) attribute is defined by RFC 4372 [RFC4372] as an answer to accounting problems caused by the use of anonymous identity in some EAP methods. In eduroam, the primary use of CUI is in incident handling, but it can also enhance local accounting. The eduroam policy requires that a given user's CUI generated for requests originating from different sites should be different (to prevent collusion attacks). The eduroam policy thus mandates that a CUI request be accompanied by the Operator-Name attribute, which is used as one of the inputs for the CUI generation algorithm. The Operator-Name requirement is considered to be the "business requirement" described in Section 2.1 of RFC 4372 [RFC4372] and hence conforms to the RFC. When eduroam started considering using CUI, there were no NAS implementations; therefore, the only solution was moving all CUI support to the RADIUS server. CUI request generation requires only the addition of NUL CUI attributes to outgoing Access-Requests; however, the real strength of CUI comes with accounting. Implementation of CUI-based accounting in the server requires that the authentication and accounting RADIUS servers used directly by the NAS are actually the same or at least have access to a common source of information. Upon processing of an Access-Accept, the authenticating RADIUS server must store the received CUI value together with the device's Calling-Station-Id in a temporary database. Upon receipt of an Accounting-Request, the server needs to update the packet with the CUI value read from the database. A wide introduction of CUI support in eduroam will significantly simplify incident handling at Service Providers. Introducing local, per-user access restriction will be possible. Visited sites will also be able to notify the home site about the introduction of such a restriction, pointing to the CUI value and thus making it possible for the home site to identify the user. When the user reports the problem at his home support, the reason will be already known.
6. Privacy Considerations The eduroam architecture has been designed with protection of user credentials in mind, as may be clear from reading this far. However, operational experience has revealed some more subtle points with regards to privacy. 6.1. Collusion of Service Providers If users use anonymous outer identities, SPs cannot easily collude by linking outer identities to users that are visiting their campus. However, this poses problems with remediation of abuse or misconfiguration. It is impossible to find the user that exhibits unwanted behaviour or whose system has been compromised. For that reason, the Chargeable-User-Identity has been introduced in eduroam, constructed so that only the IdP of the user can uniquely identify the user. In order to prevent collusion attacks, that CUI is required to be unique per user and per Service Provider. 6.2. Exposing User Credentials Through the use of EAP, user credentials are not visible to anyone but the IdP of the user. That is, if a sufficiently secure EAP method is chosen and EAP is not terminated prematurely. There is one privacy sensitive user attribute that is necessarily exposed to third parties and that is the realm the user belongs to. Routing in eduroam is based on the realm part of the user identifier, so even though the outer identity in a tunneled EAP method may be set to an anonymous identifier, it MUST contain the realm of the user, and may thus lead to identifying the user if the realm in question contains few users. This is considered a reasonable trade-off between user privacy and usability. 6.3. Track Location of Users Due to the fact that access requests (potentially) travel through a number of proxy RADIUS servers, the home IdP of the user typically cannot tell where a user roams. However, the introduction of Operator-Name and dynamic lookups (i.e., direct connections between IdP and SP) gives the home IdP insight into the location of the user.
7. Security Considerations This section addresses only security considerations associated with the use of eduroam. For considerations relating to IEEE 802.1X, RADIUS, and EAP in general, the reader is referred to the respective specification and to other literature. 7.1. Man-in-the-Middle and Tunneling Attacks The security of user credentials in eduroam ultimately lies within the EAP server verification during the EAP conversation. Therefore, the eduroam policy mandates that only EAP types capable of mutual authentication are allowed in the infrastructure, and requires that IdPs publish all information that is required to uniquely identify the server (i.e., usually the EAP server's CA certificate and its Common Name or subjectAltName:dNSName). While in principle this makes man-in-the-middle attacks impossible, in practice several attack vectors exist nonetheless. Most of these deficiencies are due to implementation shortcomings in EAP supplicants. Examples: 7.1.1. Verification of Server Name Not Supported Some supplicants only allow specifying which CA issues the EAP server certificate; its name is not checked. As a result, any entity that is able to get a server certificate from the same CA can create its own EAP server and trick the end user to submit his credentials to that fake server. As a mitigation to that problem, eduroam Operations suggests the use of a private CA that exclusively issues certificates to the organization's EAP servers. In that case, no other entity will get a certificate from the CA and this supplicant shortcoming does not present a security threat any more. 7.1.2. Neither Specification of CA nor Server Name Checks during Bootstrap Some supplicants allow for insecure bootstrapping in that they allow the simple selection of a network the acceptance of the incoming server certificate, identified by its fingerprint. The certificate is then saved as trusted for later reconnection attempts. If users are near a fake hotspot during initial provisioning, they may be tricked to submit their credentials to a fake server; furthermore, they will be branded to trust only that fake server in the future.
eduroam Identity Providers are advised to provide their users with complete documentation for setup of their supplicants without the shortcut of insecure bootstrapping. In addition, eduroam Operations has created a tool that makes correct, complete, and secure settings on many supplicants: eduroam CAT [eduroam-CAT]. 7.1.3. User Does Not Configure CA or Server Name Checks Unless automatic provisioning tools such as eduroam CAT are used, it is cumbersome for users to initially configure an EAP supplicant securely. User interfaces of supplicants often invite the users to take shortcuts ("Don't check server certificate") that are easier to set up or hide important security settings in badly accessible sub- menus. Such shortcuts or security parameter omissions make the user subject to man-in-the-middle attacks. eduroam IdPs are advised to educate their users regarding the necessary steps towards a secure setup. eduroam Research and Development is in touch with supplicant developers to improve their user interfaces. 7.1.4. Tunneling Authentication Traffic to Obfuscate User Origin There is no link between the EAP outer ("anonymous") identity and the EAP inner ("real") identity. In particular, they can both contain a realm name, and the realms need not be identical. It is possible to craft packets with an outer identity of user@RealmB, and an inner identity of user@realmA. With the eduroam request routing, a Service Provider would assume that the user is from realmB and send the request there. The server at realmB inspects the inner user name, and if proxying is not explicitly disabled for tunneled request content, may decide to send the tunneled EAP payload to realmA, where the user authenticates. A CUI value would likely be generated by the server at realmB, even though this is not its user. Users can craft such packets to make their identification harder; usually, the eduroam SP would assume that the troublesome user originates from realmB and demand there that the user be blocked. However, the operator of realmB has no control over the user and can only trace back the user to his real origin if logging of proxied requests is also enabled for EAP tunnel data. eduroam Identity Providers are advised to explicitly disable proxying on the parts of their RADIUS server configuration that process EAP tunnel data.
7.2. Denial-of-Service Attacks Since eduroam's roaming infrastructure is based on IP and RADIUS, it suffers from the usual DoS attack vectors that apply to these protocols. The eduroam hotspots are susceptible to typical attacks on edge networks, such as rogue Router Advertisements (RAs), rogue DHCP servers, and others. Notably, eduroam hotspots are more robust against malign users' DHCP pool exhaustion than typical open or "captive portal" hotspots, because a DHCP address is only leased after a successful authentication, thereby reducing the pool of possible attackers to eduroam account holders (as opposed to the general public). Furthermore, attacks involving ARP spoofing or ARP flooding are also reduced to authenticated users, because an attacker needs to be in possession of a valid WPA2 session key to be able to send traffic on the network. This section does not discuss standard threats to edge networks and IP networks in general. The following sections describe attack vectors specific to eduroam. 7.2.1. Intentional DoS by Malign Individuals The eduroam infrastructure is more robust against Distributed DoS attacks than typical services that are reachable on the Internet because triggering authentication traffic can only be done when physically in proximity of an eduroam hotspot (be it a wired socket that is IEEE 802.1X enabled or a Wi-Fi Access Point). However, when in the vicinity, an attacker can easily craft authentication attempts that traverse the entire international eduroam infrastructure; an attacker merely needs to choose a realm from another world region than his physical location to trigger Access-Requests that need to be processed by the SP, then SP-side national, then world region, then target world region, then target national, then target IdP server. So long as the realm actually exists, this will be followed by an entire EAP conversation on that path. Not having actual credentials, the request will ultimately be rejected, but it consumed processing power and bandwidth across the entire infrastructure, possibly affecting all international authentication traffic. EAP is a lock-step protocol. A single attacker at an eduroam hotspot can only execute one EAP conversation after another and is thus rate- limited by round-trip times of the RADIUS chain.
Currently, eduroam processes several hundred thousands of successful international roaming authentications per day (and, incidentally, approximately 1.5 times as many Access-Rejects). With the requirement of physical proximity, and the rate-limiting induced by EAP's lock-step nature, it requires a significant amount of attackers and a time-coordinated attack to produce significant load. So far, eduroam Operations has not yet observed critical load conditions that could reasonably be attributed to such an attack. The introduction of dynamic discovery further eases this problem, as authentications will then not traverse all infrastructure servers, removing the world-region aggregation servers as obvious bottlenecks. Any attack would then be limited between an SP and IdP directly. 7.2.2. DoS as a Side-Effect of Expired Credentials In eduroam Operations, it is observed that a significant portion of (failed) eduroam authentications is due to user accounts that were once valid but have in the meantime been de-provisioned (e.g., if a student has left the university after graduation). Configured eduroam accounts are often retained on the user devices, and when in the vicinity of an eduroam hotspot, the user device's operating system will attempt to connect to this network. As operation of eduroam continues, the amount of devices with leftover configurations is growing, effectively creating a pool of devices that produce unwanted network traffic whenever they can. Until recently, this problem did not emerge with much prominence, because there is also a natural shrinking of that pool of devices due to users finally decommissioning their old computing hardware. Recently, smartphones are programmed to make use of cloud storage and online backup mechanisms that save most, or all, configuration details of the device with a third party. When renewing their personal computing hardware, users can restore the old settings onto the new device. It has been observed that expired eduroam accounts can survive perpetually on user devices that way. If this trend continues, it can be pictured that an always-growing pool of devices will clog up eduroam infrastructure with doomed-to-fail authentication requests.
There is not currently a useful remedy to this problem, other than instructing users to manually delete their configuration in due time. Possible approaches to this problem are: o Creating a culture of device provisioning where the provisioning profile contains a "ValidUntil" property, after which the configuration needs to be re-validated or disabled. This requires a data format for provisioning as well as implementation support. o Improvements to supplicant software so that it maintains state over failed authentications. For example, if a previously known working configuration failed to authenticate consistently for 30 calendar days, it should be considered stale and be disabled. 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <http://www.rfc-editor.org/info/rfc2119>. [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, "Remote Authentication Dial In User Service (RADIUS)", RFC 2865, DOI 10.17487/RFC2865, June 2000, <http://www.rfc-editor.org/info/rfc2865>. [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. Levkowetz, Ed., "Extensible Authentication Protocol (EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004, <http://www.rfc-editor.org/info/rfc3748>. [RFC4279] Eronen, P., Ed. and H. Tschofenig, Ed., "Pre-Shared Key Ciphersuites for Transport Layer Security (TLS)", RFC 4279, DOI 10.17487/RFC4279, December 2005, <http://www.rfc-editor.org/info/rfc4279>. [RFC4372] Adrangi, F., Lior, A., Korhonen, J., and J. Loughney, "Chargeable User Identity", RFC 4372, DOI 10.17487/RFC4372, January 2006, <http://www.rfc-editor.org/info/rfc4372>. [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008, <http://www.rfc-editor.org/info/rfc5246>.
[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, DOI 10.17487/RFC5280, May 2008, <http://www.rfc-editor.org/info/rfc5280>. [RFC5580] Tschofenig, H., Ed., Adrangi, F., Jones, M., Lior, A., and B. Aboba, "Carrying Location Objects in RADIUS and Diameter", RFC 5580, DOI 10.17487/RFC5580, August 2009, <http://www.rfc-editor.org/info/rfc5580>. [RFC5997] DeKok, A., "Use of Status-Server Packets in the Remote Authentication Dial In User Service (RADIUS) Protocol", RFC 5997, DOI 10.17487/RFC5997, August 2010, <http://www.rfc-editor.org/info/rfc5997>. [RFC6613] DeKok, A., "RADIUS over TCP", RFC 6613, DOI 10.17487/RFC6613, May 2012, <http://www.rfc-editor.org/info/rfc6613>. [RFC6614] Winter, S., McCauley, M., Venaas, S., and K. Wierenga, "Transport Layer Security (TLS) Encryption for RADIUS", RFC 6614, DOI 10.17487/RFC6614, May 2012, <http://www.rfc-editor.org/info/rfc6614>. [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., Morris, J., Hansen, M., and R. Smith, "Privacy Considerations for Internet Protocols", RFC 6973, DOI 10.17487/RFC6973, July 2013, <http://www.rfc-editor.org/info/rfc6973>. 8.2. Informative References [ABFAB-ARCH] Howlett, J., Hartman, S., Tschofenig, H., Lear, E., and J. Schaad, "Application Bridging for Federated Access Beyond Web (ABFAB) Architecture", Work in Progress, draft-ietf-abfab-arch-13, July 2014. [dead-realm] Tomasek, J., "Dead-realm marking feature for Radiator RADIUS servers", 2006, <http://www.eduroam.cz/dead-realm/docs/dead-realm.html>. [DYN-DISC] Winter, S. and M. McCauley, "NAI-based Dynamic Peer Discovery for RADIUS/TLS and RADIUS/DTLS", Work in Progress, draft-ietf-radext-dynamic-discovery-15, April 2015.
[eduPKI] Delivery of Advanced Network Technology to Europe, "eduPKI Trust Profiles", 2012, <https://www.edupki.org/edupki-pma/ edupki-trust-profiles/>. [eduroam-CAT] Delivery of Advanced Network Technology to Europe, "eduroam CAT", 2012, <https://cat.eduroam.org>. [eduroam-compliance] Trans-European Research and Education Networking Association, "eduroam Compliance Statement", October 2011, <http://www.eduroam.org/downloads/docs/ eduroam_Compliance_Statement_v1_0.pdf>. [eduroam-homepage] Trans-European Research and Education Networking Association, "eduroam Homepage", 2007, <http://www.eduroam.org/>. [eduroam-service-definition] GEANT, "eduroam Policy Service Definition", Version 2.8, July 2012, <https://www.eduroam.org/downloads/docs/GN3-12- 192_eduroam-policy-service-definition_ver28_26072012.pdf>. [eduroam-start] Wierenga, K., "Subject: proposal for inter NREN roaming", message to the email@example.com mailing list, initial proposal for what is now called eduroam, 30 May 2002, <http://www.terena.org/activities/tf-mobility/ start-of-eduroam.pdf>. [IEEE.802.1X] IEEE, "IEEE Standard for Local and metropolitan area networks - Port-Based Network Access Control", IEEE 802.1X-2010, DOI 10.1109/ieeestd.2010.5409813, <http://ieeexplore.ieee.org/servlet/ opac?punumber=5409757>. [nrenroaming-select] Trans-European Research and Education Networking Association, "Preliminary selection for inter-NREN roaming", December 2003, <http://www.terena.org/activities/tf-mobility/ deliverables/delG/DelG-final.pdf>.
[radsec-whitepaper] Open System Consultants, "RadSec: a secure, reliable RADIUS Protocol", October 2012, <http://www.open.com.au/radiator/radsec-whitepaper.pdf>. [RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. Arkko, "Diameter Base Protocol", RFC 3588, DOI 10.17487/RFC3588, September 2003, <http://www.rfc-editor.org/info/rfc3588>. [RFC3958] Daigle, L. and A. Newton, "Domain-Based Application Service Location Using SRV RRs and the Dynamic Delegation Discovery Service (DDDS)", RFC 3958, DOI 10.17487/RFC3958, January 2005, <http://www.rfc-editor.org/info/rfc3958>. [RFC4017] Stanley, D., Walker, J., and B. Aboba, "Extensible Authentication Protocol (EAP) Method Requirements for Wireless LANs", RFC 4017, DOI 10.17487/RFC4017, March 2005, <http://www.rfc-editor.org/info/rfc4017>. [RFC6733] Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn, Ed., "Diameter Base Protocol", RFC 6733, DOI 10.17487/RFC6733, October 2012, <http://www.rfc-editor.org/info/rfc6733>. [RFC6929] DeKok, A. and A. Lior, "Remote Authentication Dial In User Service (RADIUS) Protocol Extensions", RFC 6929, DOI 10.17487/RFC6929, April 2013, <http://www.rfc-editor.org/info/rfc6929>. [RFC7170] Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna, "Tunnel Extensible Authentication Protocol (TEAP) Version 1", RFC 7170, DOI 10.17487/RFC7170, May 2014, <http://www.rfc-editor.org/info/rfc7170>. [RFC7542] DeKok, A., "The Network Access Identifier", RFC 7542, DOI 10.17487/RFC7542, May 2015, <http://www.rfc-editor.org/info/rfc7542>. Acknowledgments The authors would like to thank the participants in the Geant Association Task Force on Mobility and Network Middleware as well as the Geant project for their reviews and contributions. Special thanks go to Jim Schaad for doing an excellent review of the first version and to him and Alan DeKok for additional reviews. The eduroam trademark is registered by TERENA.
Authors' Addresses Klaas Wierenga Cisco Systems Haarlerbergweg 13-17 Amsterdam 1101 CH The Netherlands Phone: +31 20 357 1752 Email: firstname.lastname@example.org Stefan Winter Fondation RESTENA Maison du Savoir 2, avenue de l'Universite L-4365 Esch-sur-Alzette Luxembourg Phone: +352 424409 1 Fax: +352 422473 Email: email@example.com URI: http://www.restena.lu. Tomasz Wolniewicz Nicolaus Copernicus University pl. Rapackiego 1 Torun Poland Phone: +48-56-611-2750 Fax: +48-56-622-1850 Email: firstname.lastname@example.org URI: http://www.home.umk.pl/~twoln/