Networking With Remote Clients And Servers

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  • 1. Chapter 7 Networking with Remote Clients and Servers
  • 2. Remote Node
    • Today remote nodes connect via ISDN, DSL, cable modem, and Virtual Private Networking (VPN) across the Internet, in addition to dialing up using the plain old telephone system (POTS).
    • When connecting via remote node, a computer makes a connection through a public network to a remote access server (RAS).
  • 3. Remote Node
    • The remote access server then acts as a router, exchanging traffic between the remote computer and the network.
    • This enables the remote computer to act as though it is a network node, able to transfer files, access database information and applications, and print to network printers.
  • 4. Remote Node
  • 5. Remote Node
    • Remote computing is typically slow!
    • When the remote node accesses applications from a network location, the application must first download to the remote node before it is processed.
    • Updates made to data must be uploaded across that slow link as well.
    • A server handles requests the same way regardless of whether the node is local or remote.
  • 6. Remote Node
    • Remote node computing is simply a point-to-point link. The remote node connects directly to a remote access server via an intervening network.
  • 7. Remote Node
  • 8. Remote Node
    • Remote nodes differ from local nodes in only one way: Data travels through a modem to access the network in a remote node when it uses a dialup connection.
    • Data travels through a network interface card (NIC) to access the network in a local node. Therefore, a remote node simply treats its modem as though it were a NIC.
  • 9. Point-to-Point Connections with PPP
    • When you create a dialup connection to RAS, you must use a protocol to communicate.
    • The protocol most often used to create the point-to-point connection across the telephone network is the aptly named Point-to-Point Protocol (PPP).
    • It is based on an older protocol know as the Serial Line Internet Protocol (SLIP).
  • 10. Point-to-Point Connections with PPP
    • PPP offers several advanced capabilities.
    • When it is used to connect with a remote network, it encapsulates the upper-layer protocols.
      • This process enables a remote node to appear to be connected locally.
    • PPP’s link-control ability indicates when a connection is poor, providing for automatic termination and redialing.
  • 11. Point-to-Point Connections with PPP
    • PPP supports both Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP), which both prompt users to log on to establish a connection using encryption or clear text passwords.
  • 12. Point-to-Point Connections with PPP
  • 13. Using DSL for Remote Node
    • ADSL
    • G.Lite (DSL lite)
    • HDSL
    • VDSL
  • 14. Remote Access Service (RAS)
    • When you dial into a network as a remote node, you log into a remote access server.
    • This is often the same server that provides remote node services across the Internet, via tunneling protocols.
    • A variety of remote access servers is available.
  • 15. Remote Access Service (RAS)
  • 16. Tunneling to a Virtual Private Network (VPN)
    • VPN describes remote nodes that access a network via the Internet in a secure fashion.
    • That security is provided by tunneling protocols, along with encryption.
    • Many encryption schemes can encode data with strengths up to 128 bits, an encryption strength that virtually prevents decryption altogether.
  • 17. Tunneling to a Virtual Private Network (VPN)
    • VPN is available to clients who connect to the Internet through nearly any type of link.
    • Whether the client connects via ISDN, DSL, cable modem, or dialup line, a VPN session can usually be created.
    • 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.
    • Tunneling works by encapsulating data within IP packets in an encrypted format.
  • 18. Tunneling to a Virtual Private Network (VPN)
  • 19. Point-to-Point Tunneling Protocol (PPTP)
    • Point-to-Point Tunneling Protocol (PPTP) takes its name from PPP because it uses PPP frames in its tunneling process.
    • PPTP encapsulates PPP frames within IP datagrams, which are then transmitted across the Internet.
  • 20. Layer 2 Tunneling Protocol
    • The Layer 2 Tunneling Protocol (L2TP) was developed to establish a viable alternative to PPTP as a standard.
    • Like PPTP, L2TP is an extension of PPP that supports multiple protocols.
    • Two servers provide an L2TP tunnel: the first is an L2TP access concentrator (LAC), which is simply a RAS. The second is an L2TP network server (LNS), which provides the L2TP service.
  • 21. Remote Control
    • Remote control was an early remote networking technology that enabled users to run applications on the network with fair performance.
    • The user would create a remote control session with a computer that was connected directly to the LAN.
    • 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.
    • The graphical user interface contained the data traveling back to the remote computer.
  • 22. Remote Control
    • Remote control computing overcame some of the issues with remote node computing.
    • Because the application ran only on the LAN-connected computer, the remote computer didn’t need to be compatible with the network applications, nor did it require any additional hardware.
  • 23. Remote Control
  • 24. 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.
    • It establishes the session, maintains it, and terminates it.
  • 25. Independent Computing Architecture from Citrix
    • During the session, ICA carries keystrokes, mouse clicks, and graphical data in the form of compressed draw commands.
    • ICA is highly optimized in that it will update only the graphical data that has changed on the screen.
    • The protocol also allows file transfers between the local and remote computers.
  • 26. Independent Computing Architecture from Citrix
    • ICA requires very little bandwidth and can provide solid performance over a 20-Kbps connection.
    • This means that the average computer using a 56-Kbps modem connection will experience exceptional performance with an ICA session.
  • 27. Microsoft Remote Desktop Protocol (RDP)
    • Remote Desktop Protocol (RDP) offers much the same type of service as ICA.
    • It supplies the transport for keystrokes, mouse clicks, and display data for a server providing sessions to a thin client application.
  • 28. Microsoft Remote Desktop Protocol (RDP)
    • RDP is limited in the protocols it will run across; there’s no direct dial method.
    • RDP clients will operate only across a TCP/IP network.
    • If you need to run remote sessions across a network that is solely IPX/SPX or NetBEUI, you would be required to use Citrix MetaFrame.