• No results found

OSSIR, November /45

N/A
N/A
Info
Download
Protected

Academic year: 2021

Share "OSSIR, November /45"

Copied!
45
0
0

Loading.... (view fulltext now)

Download now ( 45 Page )

Full text

(1)
(2)

Real-time Communication

Applications

(3)

Protocols

(4)

The basics of IP telephony

Registration

Alice

Address:

A

Port:

Pa

Bob

Address:

B

Port:

Pb

network core

(registrars, proxies, …)

•

 

Authentication uses http-style digest MD5 challenges

•

 

Content can protected with TLS but …

•

 

SIP often uses plain UDP

(5)

Inter-Server Communication

Alice

Address:

A

Port:

Pa

Bob

Address:

B

Port:

Pb

SIP: SMTP-like (no real limitation)

XMPP: Requires TLS and use of certificates

inter-server communication

end-to-end encryption for IM uses OTR

(Off The Record messaging)

(6)

The basics of IP telephony

A sample call

Alice

Address:

A

Port:

Pa

Bob

Address:

B

Port:

Pb

network core

(7)

The basics of IP telephony

A sample call

Alice

Address:

A

Port:

Pa

Bob

Address:

B

Port:

Pb

network core

(8)

The basics of IP telephony.

… MEDIA over (S)RTP …

Alice

Address:

A

Port:

Pa

Bob

Address:

B

Port:

Pb

network core

(9)

Encrypting RTP

 

SRTP provides tools for

encrypting RTP flows

 

Key management was

commonly based on PKIs until

(10)

Reality check!

(11)

Standard NAT use

(12)

Less standard NAT usage:

End – to –end services

NAT

NAT

(13)

Session initialization with SIP and XMPP

INVITE sip:[email protected] SIP/2.0 Via: SIP/2.0/UDP 10.43.122.3;branch=1 From: sip:[email protected];tag=4ad340f To: sip:[email protected]

Contact: <sip:[email protected]> Call-ID: [email protected] Cseq: 12442 INVITE

v=0

o=user 14341433 14341433 IP4 10.43.122.3 s=.

t=0 0

c=IN IP4 10.43.122.3 m=audio 13222 RTP/AVP 0 a=rtpmap:0 PCMU/8000 <iq from='[email protected]/balcony' id='hs81w639' to='[email protected]/orchard' type='set'> <jingle xmlns='urn:xmpp:jingle:1' action='session-accept' initiator='[email protected]/orchard' responder='[email protected]/balcony' sid='a73sjjvkla37jfea'>

<content creator='initiator' name='voice'>

<description xmlns='urn:xmpp:jingle:apps:rtp:1' media='audio'> <payload-type id='18' name='G729'/>

</description> <transport xmlns='urn:xmpp:jingle:transports:raw-udp:1'> <candidate component='1' generation='0' id='z7sdjb01hf' ip='208.68.163.214' port='9876'/> <candidate component='2' generation='0' id='hg92lsn10b' ip='208.68.163.214' port='9877'/> </transport> </content> </jingle> </iq>

(14)

And then NATs were born …

NAT/Firewall

Address:

F

Alice

Private Address:

Ap

Call:

To: B

Media: Ap

Bob

Address:

B

Call:

To: B

Media: Ap

(15)

How do NATs work …

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

MSG:

Dst: 130.79.200.22 : 80

Src: 192.168.0.12 : 2368

Server

Address:

130.79.200.22

MSG:

Dst: 130.79.200.22 : 80

Src: 212.50.2.18 : 8632

NAT

Public Address:

212.50.4.18

Internal

host:port

NAT

port

(16)

How do NATs work …

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

MSG:

Dst: 192.168.0.12 : 2368

Src: 130.79.200.22 : 80

Server

Address:

130.79.200.22

MSG:

Dst: 212.50.4.18 : 8632

Src: 130.79.200.22 : 80

NAT

Public Address:

212.50.4.18

Internal

host:port

NAT

port

(17)

How do NATs work …

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

MSG:

Dst: 192.168.0.12 : 2368

Src: 60.55.68.53 : 9595

Server

Address:

130.79.200.22

NAT

Public Address:

212.50.4.18

Internal

host:port

NAT

port

192.168.0.12 : 2368

8632

Bob

Address:

60.55.68.53

Endpoint-Independent Mapping

(18)

Basic Firewall and NAT Traversal

STUN

Answer:

To: A

Media: B

NAT

Address:

F

Alice

Address:

Ap

Port:

Pa

Address:

Bob

B

STUN

Server

What are my

address and port?

Address:

F

Port: Pf

Call:

To: B

Media: F:Pf

STUN

Server

(19)

How do NATs work …

Address (and port) dependent filtering

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

MSG:

Dst: 130.79.200.22 : 80

Src: 192.168.0.12 : 2368

STUN Server

Address:

130.79.200.22

MSG:

Dst: 130.79.200.22 : 80

Src: 212.50.2.18 : 8632

NAT

Public Address:

212.50.4.18

Internal

host:port

NAT

port

Active connections

host:port

(20)

Internal

host:port

NAT

port

Active connections

host:port

192.168.0.12 : 2368

8632

130.79.200.22 (: 80)

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

MSG:

Dst: 192.168.0.12 : 2368

Src: 130.79.200.22 : 80

STUN Server

Address:

130.79.200.22

MSG:

Dst: 212.50.4.18 : 8632

Src: 130.79.200.22 : 80

NAT

Public Address:

212.50.4.18

How do NATs work …

(21)

Internal

host:port

NAT

port

Active connections

host:port

192.168.0.12 : 2368

8632

130.79.200.22 (: 80)

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

STUN Server

Address:

130.79.200.22

NAT

Public Address:

212.50.4.18

Bob

Address:

60.55.68.53

STOP

Endpoint-Independent Mapping

Endpoint-Dependent Filtering

How do NATs work …

(22)

Internal

host:port

NAT

port

Active connections

host:port

192.168.0.12 : 2368

8632

130.79.200.22 (: 80)

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

STUN Server

Address:

130.79.200.22

NAT

Public Address:

212.50.4.18

Bob

Address:

60.55.68.53

MSG:

Dst: 60.55.68.53 : 80

Src: 192.168.0.12 : 2368

60.55.68.53 (: 80)

How do NATs work …

(23)

Internal

host:port

NAT

port

Active connections

host:port

192.168.0.12 : 2368

8632

130.79.200.22 (: 80)

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

STUN Server

Address:

130.79.200.22

NAT

Public Address:

212.50.4.18

Bob

Address:

60.55.68.53

60.55.68.53 (: 80)

MSG:

Dst: 192.168.0.12 : 2368

Src: 60.55.68.53 : 80

Endpoint-Independent Mapping

Endpoint-Dependent Filtering

How do NATs work …

(24)

How do NATs work …

Endpoint dependent mapping

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

MSG:

Dst: 130.79.200.22 : 80

Src: 192.168.0.12 : 2368

STUN Server

Address:

130.79.200.22

MSG:

Dst: 130.79.200.22 : 80

Src: 212.50.2.18 : 8632

NAT

Public Address:

212.50.4.18

Internal

host:port

NAT

port

Active connections

host:port

(25)

Internal

host:port

NAT

port

Active connections

host:port

192.168.0.12 : 2368

8632

130.79.200.22 (: 80)

How do NATs work …

Endpoint dependent mapping

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

MSG:

Dst: 192.168.0.12 : 2368

Src: 130.79.200.22 : 80

STUN Server

Address:

130.79.200.22

MSG:

Dst: 212.50.4.18 : 8632

Src: 130.79.200.22 : 80

NAT

Public Address:

(26)

Internal

host:port

NAT

port

Active connections

host:port

192.168.0.12 : 2368

8632

130.79.200.22 (: 80)

How do NATs work …

Endpoint dependent mapping

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

STUN Server

Address:

130.79.200.22

NAT

Public Address:

212.50.4.18

Bob

Address:

60.55.68.53

MSG:

Dst: 60.55.68.53 : 80

Src: 192.168.0.12 : 2368

(27)

Internal

host:port

NAT

port

Active connections

host:port

192.168.0.12 : 2368

8632

130.79.200.22 (: 80)

192.168.0.12 : 2368

9391

60.55.68.53 (: 80)

How do NATs work …

Endpoint dependent mapping

NAT

Internal Address:

192.168.0.254

Alice

192.168.0.12

STUN Server

Address:

130.79.200.22

NAT

Public Address:

212.50.4.18

Bob

Address:

60.55.68.53

MSG:

Dst: 192.168.0.12 : 2368

Src: 60.55.68.53 : 80

Endpoint-Dependent Mapping

Endpoint-Dependent Filtering

(28)

Universal Plug and Play (UPnP)

Designed for zero-configuration networking

and to allow devices to:

 

dynamically join a network and obtain an

IP address

 

announce its name

 

advertise capabilities

 

discover other devices and their

capabilities

 

Standardized as a 73-part International

Standard, ISO/IEC 29341, in December,

2008.

www.upnp.org

Makes it easy to:

 

Learn the external (public) address of an

internet gateway

 

Enumerate existing port mappings

 

Add and remove port mappings

(29)

Relaying Media

TURN

Server

Address:

T

Port:

Pt

Symmetric NAT/Firewall F1:p2 Symmetric

NAT/Firewall F1:P1

Alice

Address: Ap

Port: Pa

Bob

Address: B

Call:

To: B Media: T:Pt

(30)

Relaying Media

TURN

Server

Address:

T

Port:

Pt

Symmetric NAT/Firewall F1:p2 Symmetric

NAT/Firewall F1:P1

Alice

Address: Ap

Port: Pa

Bob

(31)

Relaying Media The SIP Way

Latching

SIP

Server

Address:

T

Port:

Pt

NAT/Firewall

Alice

Address: Ap

Port: Pa

Bob

(32)

Relaying Media The SIP Way

Latching

SIP

Server

Address:

T

Port:

Pt

NAT/Firewall

Alice

Address: Ap

Port: Pa

Bob

(33)

Relaying Media

Relay Server

symmetric firewall

symmetric NAT/firewall

non-scalable

expensive

complex

SIP clients behind a symmetric NAT/ firewall SIP clients behind a

(34)

Using P2P networks for NAT Traversal

p2p

p2p

Custom P2P network

symmetric firewall symmetric firewall custom p2p clients

custom p2p relay clients

p2p

p2p

p2p

p2p

p2p

p2p

 

Skype – among the first to implement the

technique

 

P2PSIP – set off to imitate Skype. No

conclusive results after four years

 

Jingle Nodes – an interesting alternative that

(35)

Could we please have IPv6 now?

(36)

Could we please have IPv6 now?

… this should simplify VoIP

(37)

VoIP and IPv6 – demo version

Alice

2001:660::2

Bob

2001:660::1

network core

(38)

VoIP and IPv6 – demo version

Alice

2001:660::2

Bob

2001:660::1

network core

(39)

VoIP and IPv6 – demo version

… MEDIA …

Alice

2001:660::2

Bob

2001:660::1

network core

(40)

Reality check!

(41)

Reality check!

Bob

Alice

2001:660::2

NAT

SIP network

130.79.12.64

VPN

Priv: 172.16.0.0

Pub: 64.233.187.99

Alice’s list of addresses:

2001:660::2

192.168.0.6

Stun Relay Server 212.50.4.12

192.168.0.6

(42)

How to avoid relaying?

Interactive Connectivity Establishment

(ICE)

(43)

Address management with ICE

Bob

216.109.112.135

Alice

192.168.0.6

SIP network

NAT

130.79.12.64

VPN

Priv: 172.16.0.0

Pub: 64.233.187.99

Please try me on any of

the following:

2001:660::2

192.168.0.6

Stun Relay Server

212.50.4.12

Alice’s list of addresses:

2001:660::2

(44)

Address management with ICE

Bob

216.109.112.135

Alice

192.168.0.6

SIP network

NAT

130.79.12.64

VPN

Priv: 172.16.0.0

Pub: 64.233.187.99

Stun Relay Server 212.50.4.12

Alice’s list of addresses:

2001:660::2

192.168.0.6

ERROR 172.16.0.9

ERROR ERROR

(45)

References

Download now ( PDF - 45 Page - 2.93 MB )

Related documents

PRRSV structure, replication and recombination: Origin of phenotype and genotype diversity

Genomic sequence and virulence comparison of four Type 2 porcine reproductive and respiratory syndrome virus strains. Sequence analysis of strains of avian infectious

2017/2018 MINNESOTA HABITAT STAMP CONTEST RULES

WHEREAS, if the ARTIST'S DESIGN is the winning entry for use on the 2017/2018 STAMP, the ARTIST agrees to the conditions concerning reproduction rights contained in

Handstahow to do handstandsnd

Over a relatively short period of time (anywhere from 5-20 days), a 60- second pushup position hold can turn into a 60-second wall handstand, so long as you inch your feet up the

STATE OF FLORIDA BOARD OF MEDICINE FINAL ORDER ON PETIMON FOR DECLARATORY STATEMENT

Buprenorphine and any material, compound, mixture, or preparation containing buprenorphine qualifies as a Schedule V drug pursuant to Section 893.03(5Xb), Florida Statutes9. Based

Chronic Pain Costs Debated by Colleen Shaddox Mar 1, :47 am

Health care advocates are using a photo exhibit to lobby Connecticut state lawmakers on a measure regulating insurance rules for pain medication. Pain Foundation will start a

Child labor: a critical discourse analysis

The primary documents that were examined are the ILO’s conventions on child labor and other policy documents, namely, the Children’s Act of Ghana, the African Union’s African

Menstrual Hygiene Practices and Sources of Menstrual Hygiene Information among Adolescent Secondary School Girls in Abakaliki Education Zone of Ebonyi State

to describe the menstrual hygiene practices and sources of menstrual hygiene information among the respondents and chi-square statistic was used to determine whether

Nanopore Detachment Kinetics of Poly(A) Binding Proteins from RNA Molecules Reveals the Critical Role of C-Terminus Interactions

Considering that the probability that two PABPs on a poly(A) streak will be in the cooperative mode (head-to-head) is 25% if no preferred interaction occurs between the C-terminus,