iLab2 Introduction to SIP Daniel Raumer raumer@net.in.tum.de - PowerPoint PPT Presentation

Lehrstuhl Netzarchitekturen und Netzdienste Institut für Informatik Technische Universität München iLab2 – Introduction to SIP Daniel Raumer raumer@net.in.tum.de

Agenda  SIP - What?  SIP - How?  Repetition Security iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 2

SIP – What?  RFC 2543 – Session Initiation Protocol  Definition: “SIP – An application layer signalling protocol that defines initiation modification and termination of interactive, multimedia communication sessions between users!“  Current RFC 3261  Today used for  VoIP (mainly)  Instant Messaging (MSN) • Messaging systems often use SIMPLE  Simplified version of SIP  Online Games  Signalling Protocol for Next Generation Networks • All IP Networks (IP Multimedia Subsystem - IMS) iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 3

SIP – What?  RFC 2543 – Session Initiation Protocol  Definition: “SIP – An application layer signalling protocol that defines initiation modification and termination of interactive, multimedia communication sessions between users!“  Current RFC 3261 1996: First technology concept drafts 1999: RFC 2543 2000: SIP became signaling protocol in the 3GPP and element in IMS 2002: official IETF Standard …increase of application & a lot of extensions iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 4

The Protocol  Application Layer Protocol  Signaling Protocol for IP Networks opposed to PSTN SS7  Text based – Similarities to HTTP  Uses similar status codes SIP, (RTP,…) Application • 200  OK • 3xx  Moved Transport UDP TCP • 4xx  Errors Internet IP (IPv4, IPv6)  RFC 3261 defines the Framework Network … Ethernet  Header fields Access  Protocol • What to do when • Which messages are sent at which point of the session • …  Additional RFCs complement this basic framework • Privacy (RFC 3323) • Compression (RFC 3320) • Body Content, Media Description… iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 5

What does it do?  Session Initiation  Localization of users  Using SIP URIs: ilab2@net.in.tum.de  Presence indication  Negotiation of Parameters  Codecs to be used, Security Parameters  Setup of the session  Media targets  Management and maintenance of the session  Forwarding or cancelation of a session  Invite, re- Invites, … iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 6

What it does NOT  SIP is not a ready-for-use application  It is not Instant messaging, VoIP, or Video on demand.  SIP does not transport media  but does work with Session Description Protocol (SDP)  SIP does not provide QoS  but can work with Resource Reservation Protocol (RSVP) and Real-Time Transport Protocol (RTP)  SIP does not provide Authentication  but works with RADIUS and LDAP  “ SIP needs alphabet soup to stay healthy !” iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 7

SIP Based VoIP Call sip:bob@someplace Protocol / Negotiation Call Protocol / End Call RTP Session iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 8

Reinvitation sip:bob@someplace Sorry Bob is not here – Try mobile sip:bobmobile@someplace iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 9

SIP Based VoIP Call Furni.er Jamai.ca iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 10

Repetition Security  Security Objectives:  Integrity,  Authenticity,  Confidentiality,  Availability,  Accountability  Some attack types (not distinct)  Replay Attack  Relay Attack  Monitoring/Snooping  (Identity-)Spoofing  DoS (e.g. BYE message injecting)  … iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 11

SIP Security “ Alphabet Soup”  SRTP (Secure Real-Time Transport Protocol) RFC 3711  SDES (Session Description Protocol Security Descriptions) RFC 4568  Key exchange for RTP – but requires a secure channel (TLS or S/MIME)  ZRTP (Zimmermann Real-Time Transport Protocol) RFC 6189  Diffie-Hellman for the RTP  Man in the middle?  …but SIPS is usually realized over TLS hop by hop iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 12

Content of the Lab  Much short lab  So fun  Such less coding WOW iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 13

The End iLab2 – Introduction to the Multicast and SIP – Daniel Raumer – 2012-11-08 14