Virtual Private Network, Remote Access - Network Security Fundamentals - Lecture Slides, Slides of Cryptography and System Security

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Remote Access

Chapter 4

Learning Objectives

 Understand implications of IEEE 802.1x and how it is used

 Understand VPN technology and its uses for securing remote access to networks  Understand how RADIUS authentication works

 Understand how TACACS+ operates  Understand how PPTP works and when it is used

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IEEE 802.1x

 Internet standard created to perform authentication services for remote access to a central LAN

 Uses SNMP to define levels of access control and behavior of ports providing remote access to LAN environment

 Uses EAP over LAN (EAPOL) encapsulation method

802.1x General Topology

Telnet

 Standard terminal emulation protocol within TCP/IP protocol suite defined by RFC 854

 Utilizes UDP port 23 to communicate

 Allows users to log on to remote networks and use resources as if locally connected

Controlling Telnet

 Assign enable password as initial line of defense

 Use access lists that define who has access to what resources based on specific IP addresses

 Use a firewall that can filter traffic based on ports, IP addresses, etc

VPN Diagram

Tunneling

 Enables one network to send its data via another network’s connections

 Encapsulates a network protocol within packets carried by the second network

VPN Options

 Install/configure client computer to initiate necessary security communications

 Outsource VPN to a service provider

 Encryption does not happen until data reaches provider’s network

Service Providing Tunneling

Remote Authentication Dial-in User

Service (RADIUS)

 Provides a client/server security system  Uses distributed security to authenticate users on a network  Includes two pieces  Authentication server  Client protocols  Authenticates users through a series of communications between client and server using UDP

Authenticating with a RADIUS Server

Terminal Access Controller Access

Control System (TACACS+)

 Authentication protocol developed by Cisco  Uses TCP – a connection-oriented transmission – instead of UDP  Offers separate acknowledgement that request has been received regardless of speed of authentication mechanism  Provides immediate indication of a crashed server