Transcript Document

VKSF 423 System
Administration III
Thin Client Computing
Announcements

Lab:
– Implementation terminal servers and thin
clients.
Recap from Last Time
What do our users do?
 What computing resources do they need to
accomplish their tasks?
 If the minimal desktop computers we can
buy far exceed our needs what are our
options?
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What are the trends in the
Business World
Incredible cost pressures
 Rising salaries for skilled systems
administrators
 Desire to decrease TCO
 Historically low interest rates make capital
investments attractive by lowering internal
rate of return in ROI analysis

Thin-client Devices
Only needs to process keyboard input and
screen output
 No hard drive, no CDROM drive, no floppy
drive, no moving parts
 Cannot be used away from the network
 Cheap and easy to replace
 Can any device be thin?

Why Thin Clients?
Provide ability to aggregate computing
resources in servers instead of spreading
them around in clients
 Centralization
 Consolidation
 Virtualization
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Thin-client Model Benefits
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Lower total cost of ownership (TCO)
Easier software installation, uninstallation and
maintenance
Centralized support, access control, and administration
Lowered security risks
Uses existing infrastructure
Lower power consumption
Applications available anywhere on demand
Disaster recovery
No end of life
Thin-client Model Limitations
Management – Business side
 3D applications
 Specialized hardware needs
 Laptops
 Are these valid limitations?
 Can we think of ways of getting around
them and still keep the thin client model?
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The WYSE Choice
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Biggest provider of thin
clients
Hardware Devices
– Terminal Devices
– Tablet PCs
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Software
– Management
• Rapport
• Alcatraz
– Speed
• Expedian
Available Server Technologies
Windows Terminal Server
 Citrix MetaFrame Presentation Server
 Linux Terminal Server Project
 Sun and Sun Rays
 VNC
 Nomachine
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Comparative Points
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How thin is thin?
– Desktop and server side hardware requirements
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Where does the processing actually take place?
– What is going over the wire?
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What management tools are available?
– Ratio of sysadmins to desktops
– Characteristics of your enterprise
– Future technology needs
LTSP
Linux Terminal Server Project
 Supports many devices and platforms
 Supports many services
 “Zero cost” solution
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– No software or hardware licensing
No operating system installed locally
 Limited points of failure
 Freely available “cookbook” directions
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LTSP Client Side
Network Interface Card
 Video Card Chipset
 Monitor Information
 Etherboot, PXE, or eprom
 If the client has more memory, it can be
configured to store programs locally
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LTSP Server side
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Required
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Syslog
NFS
DHCP
TFTP
LTSP Core
LTSP Kernel
LTSP X Core
LTSP X Fonts
Optional
– NIS
Files Modified by LTSP
LTSP Initialization Script
 /etc/hosts
 /etc/dhcpd.conf
 /opt/ltsp/i386/etc/lts.conf
 /etc/exports
 /etc/xinetd.d/tftp
 XDMCP
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LTSP - Theory of Operation
Client boots into from the network
 DHCP
 TFTP
 DHCP
 NFS
 SYSLOG
 XDMCP
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LTSP Etherboot DHCP Exchange
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Frame 1
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Message type: Boot Request (1)
Client hardware address:
00:50:ba:d3:a0:ab
Option 53: DHCP Message Type =
DHCP Discover
Option 57: Maximum DHCP Message
Size = 1500
Option 55: Parameter Request List
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1 = Subnet Mask
3 = Router
12 = Host Name
43 = Vendor-Specific Information
Frame 2
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Message type: Boot Reply (2)
Your (client) IP address: 10.110.53.2
Next server IP address: 10.110.53.1
Client hardware address:
00:50:ba:d3:a0:ab
Boot file name: /lts/vmlinuz-2.4.19-ltsp1
Option 53: DHCP Message Type =
DHCP Offer
Option 54: Server Identifier =
10.110.53.1
Option 51: IP Address Lease Time = 6
hours
Option 1: Subnet Mask = 255.255.255.0
Option 3: Router = 10.110.53.254
Option 12: Host Name = "ws001"
LTSP Etherboot DHCP Exchange
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Frame 3
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Message type: Boot Request (1)
Client hardware address:
00:50:ba:d3:a0:ab
Option 53: DHCP Message Type =
DHCP Request
Option 54: Server Identifier =
10.110.53.1
Option 50: Requested IP Address =
10.110.53.2
Option 57: Maximum DHCP Message
Size = 1500
Option 60: Vendor class identifier =
"Etherboot-5.0"
Option 55: Parameter Request List
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1 = Subnet Mask
3 = Router
12 = Host Name
43 = Vendor-Specific Information
17 = Root Path
Frame 4
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Message type: Boot Reply (2)
Your (client) IP address: 10.110.53.2
Next server IP address: 10.110.53.1
Client hardware address:
00:50:ba:d3:a0:ab
Boot file name: /lts/vmlinuz-2.4.19-ltsp1
Option 53: DHCP Message Type =
DHCP ACK
Option 54: Server Identifier =
10.110.53.1
Option 51: IP Address Lease Time = 6
hours
Option 1: Subnet Mask = 255.255.255.0
Option 3: Router = 10.110.53.254
Option 12: Host Name = "ws001"
Option 17: Root Path =
"10.110.53.1:/opt/ltsp/i386“
LTSP TFTP Exchange
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Frame 1
Src Addr: 10.110.53.2
Dst Addr: 10.110.53.1
Trivial File Transfer Protocol
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Opcode: Read Request (1)
Source File: /lts/vmlinuz-2.4.19-ltsp-1
Type: octet
Option: blksize = 1432
Frame 2
Src Addr: 10.110.53.1
Dst Addr: 10.110.53.2
Trivial File Transfer Protocol
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Opcode: Option Acknowledgement (6)
Option: blksize = 1432
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Frame 3
Src Addr: 10.110.53.2
Dst Addr: 10.110.53.1
Trivial File Transfer Protocol
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Opcode: Acknowledgement (4)
Block: 0
Frame 4
Src Addr: 10.110.53.1
Dst Addr: 10.110.53.2
Trivial File Transfer Protocol
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Opcode: Data Packet (3)
Block: 1
Data (1432 bytes)
LTSP DHCP Exchange
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Frame 1
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Message type: Boot Request (1)
Client hardware address: 00:50:ba:d3:a0:ab
Option 53: DHCP Message Type = DHCP
Discover
Option 55: Parameter Request List
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1 = Subnet Mask
28 = Broadcast Address
3 = Router
15 = Domain Name
6 = Domain Name Server
12 = Host Name
17 = Root Path
Frame 2
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Message type: Boot Reply (2)
Your (client) IP address: 10.110.53.2
Next server IP address: 10.110.53.1
Client hardware address: 00:50:ba:d3:a0:ab
Boot file name: /lts/vmlinuz-2.4.19-ltsp-1
Option 53: DHCP Message Type = DHCP
Offer
Option 54: Server Identifier = 10.110.53.1
Option 51: IP Address Lease Time = 6 hours
Option 1: Subnet Mask = 255.255.255.0
Option 28: Broadcast Address = 10.110.53.255
Option 3: Router = 10.110.53.254
Option 15: Domain Name = "ltsp.local"
Option 6: Domain Name Server = 10.110.53.1
Option 12: Host Name = "ws001"
Option 17: Root Path =
"10.110.53.1:/opt/ltsp/i386"
LTSP DHCP Exchange
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Frame 3
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Message type: Boot Request (1)
Client hardware address: 00:50:ba:d3:a0:ab
Magic cookie: (OK)
Option 53: DHCP Message Type = DHCP
Request
Option 54: Server Identifier = 10.110.53.1
Option 50: Requested IP Address =
10.110.53.2
Option 55: Parameter Request List
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1 = Subnet Mask
28 = Broadcast Address
3 = Router
15 = Domain Name
6 = Domain Name Server
12 = Host Name
17 = Root Path
Frame 4
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Message type: Boot Reply (2)
Your (client) IP address: 10.110.53.2
Next server IP address: 10.110.53.1
Client hardware address: 00:50:ba:d3:a0:ab
Boot file name: /lts/vmlinuz-2.4.19-ltsp-1
Option 53: DHCP Message Type = DHCP
ACK
Option 54: Server Identifier = 10.110.53.1
Option 51: IP Address Lease Time = 6 hours
Option 1: Subnet Mask = 255.255.255.0
Option 28: Broadcast Address = 10.110.53.255
Option 3: Router = 10.110.53.254
Option 15: Domain Name = "ltsp.local"
Option 6: Domain Name Server = 10.110.53.1
Option 12: Host Name = "ws001"
Option 17: Root Path =
"10.110.53.1:/opt/ltsp/i386“
Practical Application of LTSP
402 OS Scripting
 Only terminal mode is needed
 All users use NFS
 No prelab
 Access anywhere
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Windows Terminal Server
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Comes standard with Windows Server beginning
with Windows 2000 Server
Came out of NT4 Terminal Server Edition
Uses RDP Protocol
Can be used for administration or application
deployment
Requires licensing for application deployment
Windows XP was not the first to have terminal
services
Windows 2003 RDP 5.2
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Can redirect sound, serial ports, and printers
Remote Users group controls access
Group Policy
RC4 128-bit stream cipher
Disconnection vs. Logoff
Terminal Services Session Directory
– Requires Enterprise Edition
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Client is installed in Windows XP and later
Licensing
Windows Server License
 Windows Client Access License
 Windows Terminal Services Client Access
License
 Terminal Services Licensing Server
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Limitations of Windows Terminal
Services
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No easy way of
– Pushing just applications
– Building web portals
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Unsupported clients available
Why Citrix MetaFrame?
Application Server
 Distributed Management
 Centralized Resources
 95% Fortune 500
 95% European FT 100
 100% Fortune 100
 Over 120,000 Organizations
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Current Flavors of Citrix
XPs - Standard
 XPa - Access
 XPe - Enterprise
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XPs
Ideal for small environments
 Includes ICA protocol (Independent
Computing Architecture), client platform
support, network protocol support, seamless
desktop
 Does not including load balancing features
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XPa
For medium sized businesses
 Includes all of XPs features
 Includes load management support
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XPe
Enterprise version
 Includes all of XPa features
 Installation manager, resource manager, and
network manager
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Drawbacks
Laptop management
 Selling to Management
 Poor application design
 High initial cost if client server model is
already implemented
 3D Applications/Specific hardware needs
 Licensing model
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Licensing
Windows Server License
 Windows Client Access License
 Windows Terminal Services Client Access
License
 Terminal Services Licensing Server
 Citrix Server License
 Citrix Connection License
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Metaframe
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“Any client device, any network
connection, any network protocol, seamless
desktop integration”
Metaframe
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“Any client device…”
– Any application can be run on any OS
– Windows CE Devices, Windows 16-bit/32-bit,
UNIX, Mac, Java, OS/2 Warp, EPOC/Symbol,
DOS 16-bit/32-bit
– Example: MS-DOS 5.0 running Microsoft
Office 2000
Metaframe
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“Any network
connection…”
– Little client side
performance impact
– Optimized for connections
as low as 14.4Kbps
– Mouse clicks and keyboard
strokes from client to server
– Screen updates sent from
server to client
Metaframe
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“Any network protocol…”
– Works at Presentation level of the OSI model
– TCP/IP, IPX, SPX, Net BIOS, NetBEUI, PPP,
Async, ISDN, Frame Relay, ATM, and any
other existing or developing protocols.
Metaframe
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“Desktop integration.”
– Application appears local to users
– Limit questions posed to IT staff
– No retraining for how users run applications
Metaframe
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Application launching and embedding
– Launching allows users to open a program from
a web browser into a new window
– Embedding opens the application right in the
web browser
Components of the ICA Packet
ICA Packet
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Reliable:
– is used in connectionless protocols such as IPX and
UDP to provide reliable, error-free delivery.
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Encryption:
– is used as the preamble for managing any packets that
contain encrypted data.
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Compression:
– is used as the preamble for managing any packets that
contain compressed data.
ICA Packet
 Command
byte:
– Is the only required ICA command byte. This is
the beginning of the base ICA protocol packet.
 Command
data:
– Contains optional data bytes associated with the
specific command. The length of the data is
dependent on the command.
Deployment in Windows 2000
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Problems with deployment based on
computers
– All users must use the same application suite
– Same user must login on that terminal all the
time
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Problems with installs based on users
– What happens if that user only logs into that
computer once?
Deployment in Citrix
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Programs are installed once on the server and then
deployed for a user or group of users
No additional data is stored on the client
Hardware can be easily attached and used with the
Citrix server
Installation Manager used for pushing around
applications in the farm
Disaster Recovery
All the data and applications are held
centrally
 Servers within a farm can be divided across
physical boundaries
 Clients become more meaningless and can
be easily swapped with cheap replacements
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Storage Solutions
Servers talk directly to the storage unit
decreasing latency in file transactions
 Storage is consolidated in once place
 Can be used to prohibit the user from saving
files to their local computers
 Can be used to transfer files to and from the
server
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