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Network Services—VPN and VoIP Chapter 11. Knowledge Concepts Understanding VPN technology Getting a grip on encryption The business application of VoIP.

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Presentation on theme: "Network Services—VPN and VoIP Chapter 11. Knowledge Concepts Understanding VPN technology Getting a grip on encryption The business application of VoIP."— Presentation transcript:

1 Network Services—VPN and VoIP Chapter 11

2 Knowledge Concepts Understanding VPN technology Getting a grip on encryption The business application of VoIP and VPNs How VoIP works

3 Important Terms VPN RADIUS Authentication Provisioned Encryption PPTP, L2TP,IPSec Firewall Proxy server PKI DES Symmetric and asymmetric encryption VoIP H.323, SIP, LDAP

4 Tunneling with a VPN

5 Why VPNs? Improves ability to communicate outside of a company Enables secure access Provides rapid provisioning of capacity as needed

6 How Remote Access Via a VPN Works

7 VPN Characteristics Logical network Isolates customer traffic on shared provider facilities Looks like a private network Runs on either packet switched data network or circuit- switched public network Can be deployed over a wide range of network technologies Uses shared carrier infrastructure

8 Deployment Models Customer-based – Carriers install gateways, routers and hardware on customer premises – Customer manages security Network-based – Carrier houses all equipment at POP near customer location

9 VPN Frameworks Internet based – Small ISPs provide local access services in a region – Business users get end-to-end services from a variety of suppliers – Encryption used to isolate traffic and provide security – Customer provides servers wit applications/content – A RADIUS server is used to authenticate traffic for access to application/Content servers – RADIUS server is connected to a firewall

10 Provisioned VPNs Packet-switched VPN that runs across ISP backbone using Frame Relay or ATM Supports multiple protocols Provisioned services improve performance by enabling guarantees of service (QoS)

11 VPN Applications VPN is an architecture tied together and calibrated Goals are to manage security and deliver applications with minimal latency Save money by – Substituting leased lines for Internet connectivity – Reducing dial up costs

12 3 Major VPN Applications Intranets – Sit-to-site connections Remote Access – Remote workers and outside customers – Eliminates modems & remote access routers Extranets – Suppliers have specific access

13 VPN Gateway Functions Maintenance of a secure logical connection as a tunnel Tunneling is encapsulation of a data packet within an IP packet Remote ends of tunnel can be at edges of ISP or corporate boundary router Traffic is routed as encyrpted

14 Key Tunneling Protocols PPTP—Layer 2 in MS products L2TP –used by ISPs on backbone IPSec –covers encryption at 168 bit and authenticated both ends of tunnel connection – Works only in IP environment

15 VPN Security Firewalls are used to control policies for data exchange between 2 networks Routers can act as a firewall by managing packet traffic (filter) Proxy servers used to separate internal network from public services Authentication provided by RADIUS servers – Uses CHAP (Challenge Handshake Authentication Protocol) to authenticate – Tokens issued with user password to server to verify user access – New tokens generated each time a user connects

16 Basic Encryption Terminology Plaintext (aka cleartext): original, readable data Ciphertext: scrambled form of plaintext Encryption: reversible conversion of plaintext into ciphertext Decryption: conversion of ciphertext back into plaintext Crack (aka break) code: decrypt ciphertext without knowing key

17 Basic Encryption Terminology (cont’d) Key: secret allowing encryption and decryption to be restricted to possessors of key Symmetric encryption: encryption requiring a shared key for both encryption and decryption Asymmetric encryption: algorithm using a different key for decryption than for encryption

18 Encryption Encoding plain text data to hide contents with cipher text Symmetric – Sender and receiver use same key – Popular algorithms: DES, Triple DES, Blowfish Asymmetric (PKI) – Different keys with one key held publicly – Verifies message through hashing (MD5) – Types of public keys are RSA, Diffie-Hellman, PGP – PKI uses digital certificates to authenticate users and encrypt data – Verisign and Entrust

19 US Digital Signature Law USA: 15 USC §7006 Title 15: Commerce and Trade – Chapter 96: Electronic Signatures in Global and National Commerce Based on S.761 (Sponsor Sens Abraham & Spencer) – Introduced 1999-003-25 – Came into force 2000-06-30 – See Legal Information Institute entry at

20 Electronic Payments Credit card transactions Digital cash Micropayments

21 Credit Card Transactions No documented case of interception of credit-card data while in transit through the Internet – Most sites use Secure Sockets Layer (SSL) – Credit-card information theft has occurred from servers – All sensitive data on Web servers should be encrypted Safety of allowing a merchant to use credit-card information depends on the merchant – No worse to give info to reputable firm via Web than to clerk who takes card away from view

22 Credit Cards & Escrow Allow buyer to register credit-card data with reputable firm – Merchant receives payment from escrow service – Escrow service bills client credit card – Insulates buyer from seller Examples: – VeriSign Cybercash – (for domain name sales) – Beseen BuyIt Button – Tradenable http://www.tradenable.com – PayPal

23 Digital Cash All credit-card transactions result in electronic audit trail Digital cash (aka e-cash) removes trail – Load a device with credits – Use device for transactions to transfer credits Requires device that can prevent – Counterfeiting (loading credits fraudulently) – Theft (removing credits fraudulently)

24 Digital Cash (cont’d) Mechanisms depend on smart cards – Devices size of credit card – Include microprocessor, RAM, power – Programmed with cryptographic tools to prevent unauthorized modification of contents – Interface allows merchant to deduct or refund credits Examples include – eCash – E-Cash Services

25 Expensive Leased Lines

26 VPN Access as an Intranet

27 VPNs and Business Before a VPN— Point-to-Point After a VPN— Tunneled

28 Encryption and VPNs

29 Evaluating a VPN Solution

30 VoIP Not yet a big player with less than 5% of market Cost savings, enhanced voice services and new applications major advantages VoIP gateways bridge circuit-switched PSTN and packet-switched Internet – Gateways packetize, and compress voice, route packets, authenticate users, and manage network of gateways

31 VoIP Hardware Enterprise gateway – Deployed between PBX and WAN device (router) for call set- up,routing, and conversion VoIP routers – Voice cards perform packetization and compression functions in a router IP PBX – Distributed telephony servers that operat ein packt-switched mode ISP VoIP gateways – Aggregate incoming traffic and routing

32 VoIP Infrastructure

33 VoIP Architecture

34 Implementing VoIP

35 VoIP Standards H.323 – Based on ISDN and limited to point-to-point applications SIP – Application layer (signaling) protocol – Establishes temp sessions for multimedia conferences, telephony, mobile phone-to-instant messaging LDAP – Standard directory server technology for Internet – Enables retrieval of information from multi-vendor directories – Used for free phone and Internet phone number hosting

36 Important Figures Figure 11.1 & 11.2 p.332-333 Figure 11.3 & 11.4 p. 334-335 Figure 11.5 p. 336 Figure 11.8 p. 339 Figure 11.10 p. 346 Figure 11.12 p. 358

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