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SIP : OpenSER in an academic environment

SIP.edu : OpenSER in an academic environment. OpenSER SUMMIT - VON – Berlin 2006. Agenda. Introduction INRIA The SIP.edu project SIP.edu at INRIA Access control with RADIUS Expected limitations and problems Future improvements. INRIA.

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SIP : OpenSER in an academic environment

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  1. SIP.edu : OpenSER in an academic environment OpenSER SUMMIT - VON – Berlin 2006

  2. Agenda • Introduction • INRIA • The SIP.edu project • SIP.edu at INRIA • Access control with RADIUS • Expected limitations and problems • Future improvements

  3. INRIA • French National Institute for Research in Computer Science and Control • Fundamental and applied research in various fields • Networking • Multimedia • Software security • Modeling living structures and mechanisms • 5000 people in 6 locations

  4. The SIP.edu project • Started in late 2003, from an Internet2 organization initiative • Aims to connect academic institutions with SIP • Two prerequisites • A user e-mail to phone number mapping mechanism • SIP address ~= email address • Integrate with an existing PBX to make non-SIP phones reachable • Not necessarily IP enabled • More than 250,000 people reachable • MIT, Harvard University, Yale, ..

  5. SIP.edu : target architecture

  6. SIP.edu at INRIA • DNS SRV records to our SIP proxy • SIP proxy : OpenSER version 1.0.1 • Directory : OpenLDAP • Gathers the information for all INRIA members • SIP PBX gateway : Asterisk + Cisco router • 12 channels to the existing PBX • PBX : TENOVIS

  7. SIP.edu at INRIA : the picture

  8. Available services • “sip:first.last@inria.fr” URIs that map with regular E.164 extensions at INRIA • Accessible to anyone from the Internet • “sip:0123456789@inria.fr” URIs, to call external E.164 extensions • Restricted to INRIA’s members • RADIUS based access control

  9. Sample call flow to a numeric extension • To initiate a call to PSTN extension 0123456789, Alice types “sip:0123456789@inria.fr" into her SIP user agent (UA); • DNS SRV query • Sent to INRIA’s SIP proxy • The proxy detects a numeric extension, and triggers the RADIUS authentication process • The proxy re-writes the INVITE to INVITE sip:0123456789@asterisk.inria.fr, which it sends to the Asterisk server; • Asterisk rings extension 0123456789 through the PSTN gateway and PBX.

  10. SIP and RADIUS : user password storage • Two alternatives • Clear text format • Insecure • Regular authentication database cannot be used • Digest-HA1: MD5(username:realm:password) • User password is kept opaque to the admin • Stored information is still sensitive • Regular authentication database cannot be used

  11. The key role of OpenSER • Call processing logic • Not that easy to handle but powerful • Modular software architecture • Many database/protocols connectors • RADIUS, SQL, Jabber, .. • External scripting integration • In our SIP.edu architecture, the LDAP information retrieval process is a shell script launched by OpenSER

  12. Expected limitations and problems • NAT issues • SPIT (SPam over IP Telephony) • Use inter-domain TLS? OpenSER already addresses those issues

  13. Future improvements • Enable RADIUS authorization by implementing group checking • Integrate with our Jabber based IM - presence solution Already possible with OpenSER

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