Unit07:

Networking with Remote Clients and Servers

Overview

• Remote Node • Remote Control • Configuring a Connection

Remote Node

• Remote nodes were computers that connected to a network via a dialup line

• Nodes connect via ISDN, DSL, cable modem, and Virtual Private Networking (VPN) across the Internet

• Remote node computing is notoriously slow, primarily because dialup

• the remote node is not much different from a local node on the network

Remote Node

Remote Node

Advantages of Remote Node Computing • ease of configuration • it can be run across any dialup line, cable, DSL and so

on • wide variety of operating systems natively support

remote access • there are no graphics restrictions

Disadvantages of Remote Node Computing • Issue of slow speed

• Driven by the need to use certain applications

• Problem for network administrators arises—licensing

• Support issues can be horrendous

Point-to-Point Connection with PPP

• PPP is based on an earlier protocol • Serial Line Internet Protocol (SLIP )• SLIP worked only on TCP/IP networks

Using DSL for Remote Node

• Digital Subscriber Line (DSL) is growing as a dialup technology for remote node

• DSL uses the same lines as regular telephone calls – ADSL – G.Lite – HDSL – VDSL

Remote Access Service (RAS)

• When you dial into a network as a remote node, you log into a remote access server

• A variety of remote access servers is available • RAS server placement is key to performance

RAS

Tunneling to a Virtual Private Network • Virtual Private Networking (VPN) describes remote nodes that

access a network via the Internet in a secure fashion • Many encryption schemes can encode data with strengths up to 128

bits • VPN is available to clients who connect to the Internet through

nearly any type of link • VPN creates a virtual point-to-point connection to the RAS • Tunneling is driven by the need to protect that virtual point-to-point

link from being interrupted or eavesdropped upon

VPN

Tunneling Protocol

• Point-to-Point Tunneling Protocol – Point-to-Point Tunneling Protocol (PPTP) takes its

name from PPP because it uses PPP – PPTP encapsulates PPP frames within IP datagram

• Layer 2 Tunneling Protocol – The Layer 2 Tunneling Protocol (L2TP) was

developed to establish a viable alternative to PPTP – Like PPTP, L2TP is an extension of PPP that

supports multiple protocols – L2TP clients follow a similar process to PPTP

Remote Control

• On the remote computer, a window would appear with the remote computer’s desktop within it

• All application processing and data remained on the LAN • the only data that traveled to the LAN from the remote

computer were keyboard and mouse clicks • Remote control computing overcame some of the issues

with remote node computing • the remote computer didn’t need to be compatible with the

network applications • little data had to traverse the connection between the

remote computer and the local node • no issues with licensing because the application ran on the

local node

Remote Control

Remote Control-Thin client

Independent Computing Architecture from Citrix • Citrix developed its ICA protocol to facilitate remote control

sessions • The protocol runs within the upper layers of the OSI

reference model, including the application, presentation, and session layers

• During the session, ICA carries keystrokes, mouse clicks, and graphical data in the form of compressed draw commands

• ICA is supported by the latest Web browsers • ICA client can dial directly into a Citrix MetaFrame server

and run a pure ICA session across the direct connection

Microsoft Remote Desktop Protocol

• Remote Desktop Protocol (RDP) offers much the same type of service as ICA

• original protocol used by Windows NT 4.0 Terminal Services Edition

• RDP clients will operate only across a TCP/IP network • RDP is also the protocol used in Windows XP’s two

native remote applications – Remote Desktop Connection application, which

provides a single remote control session to a Windows XP computer.

– Remote Assistance application

Configuring a Connection

• A typical VPN deployment begins with a remote client that needs to access the local network that is already connected to the Internet

• the client must make a second call across the Internet over the existing PPP connection

• The call connects to a RAS providing PPTP or L2TP services and creates a tunnel

Server-Side Configuration

• Ras • Windows 2000 Servers Are Equipped With Routing And

Remote Access Service (Rras )• Windows 2000 Rras Is Able To Authenticate Directly To

The Active Directory Service • Distribute Dialup Rras Servers Throughout The Network

To Reduce Dialup Telephone Costs

VPN