1. COMP1321 Digital Infrastructure Richard Henson February 2014

2. Week 14: Client-Server Networks In particular… Client-Server Platforms for Operating Systems…. In particular… Client-Server Platforms for Operating Systems….

3. Client-Server Platforms for Operating Systems Users use client machines Users use client machines Administrators manage server machines to provide network resources Administrators manage server machines to provide network resources Clients and servers mutually dependent Clients and servers mutually dependent server client

4. 21 st Century Platforms Unix already popular, but technical Unix already popular, but technical Windows 2000 Server easier maintained alternative…? Windows 2000 Server easier maintained alternative…? DEC VAX “fell of a cliff” DEC VAX “fell of a cliff”  Intel platform survived threats from RISC architecture… 64-bit alpha platform never that popular64-bit alpha platform never that popular rights to alpha chip bought by Intel (!)rights to alpha chip bought by Intel (!) never even offered when XP (client-based) was launched…never even offered when XP (client-based) was launched…

5. TWO Features of Windows 2000 Server Active Directory Active Directory  centralised resource cataloguing  control over users via group policy Scalability: Scalability:  multiple domains  hierarchy of trusted domains based on DNS naming

6. Platforms at Client-end and Server-end Windows became 64-bit on an Intel platform: Windows became 64-bit on an Intel platform:  on server motherboards Windows 2003 onwardsWindows 2003 onwards  on workstations (Vista onwards…) n Due to Microsoft’s disastrous (mis)launch of Vista…  Apple client platform had a chance to emerge and develop a good range of apps  ensured success of i-player & i-phone

7. Windows 2003 Server – what was new? Main difference at kernel level in 64-bit option Main difference at kernel level in 64-bit option  32-bit kernel unchanged… Functional enhancements: Functional enhancements:  GDI+ interface  enhanced Active Directory  Group Policy Management Console

8. BIOS Developments Earlier motherboards… Earlier motherboards…  single chip containing the BIOS on ROM and a writeable CMOS area  16-bit command line interface More recent motherboards use EFI (Extensible Firmware Interface) More recent motherboards use EFI (Extensible Firmware Interface)  32-bit command line  only really exploited with Windows 7, and 2008 Server…

9. Windows 2008 Server – what was new? Virtualisation platform Virtualisation platform  known as Hyper-V PowerShell PowerShell  more powerful range of command line options More efficient use of Active Directory across enterprise networks for user account control More efficient use of Active Directory across enterprise networks for user account control others…. others….

10. Virtualisation (Windows 2008 Server, Citrix, VMware, etc.) The use of software to allow a piece of hardware to run multiple operating system images at the same time The use of software to allow a piece of hardware to run multiple operating system images at the same time  Windows OS under Mac OS…  multiple versions of Windows OS on the same PC Slightly different from terminal services but getting popular… Slightly different from terminal services but getting popular… Enables the creation of a “virtual” (rather than actual) version of any software environment on the desktop, e.g. Operating Systems, a server, a storage device or networks, an application Enables the creation of a “virtual” (rather than actual) version of any software environment on the desktop, e.g. Operating Systems, a server, a storage device or networks, an application

11. More about booting to an Intel platform BIOS coordinates with “master boot record” (MBR) on boot partition BIOS coordinates with “master boot record” (MBR) on boot partition Should seek out a “boot loader” program and operating system Should seek out a “boot loader” program and operating system  and partition(s) containing the different media prepared in different ways Hard disk still the conventional boot medium Hard disk still the conventional boot medium  partitions give choice of bootable media CDs & USBs only have one partitionCDs & USBs only have one partition

12. Partitions, Hard Disks and Multiple Operating Systems MBR must be on the first (C:) partition MBR must be on the first (C:) partition Possible to have different operating systems on the same hard disk… Possible to have different operating systems on the same hard disk…  varieties of Windows  varieties of Unix… BUT… BUT…  Master Boot Record systems different on Unix and Windows  still possible to have ONE Unix partition…

13. Storage of User/System Settings for clients: The Registry Early Windows extended DOS text files of system & user settings: Early Windows extended DOS text files of system & user settings:  SYSTEM.INI enhanced CONFIG.SYS  WIN.INI enhanced AUTOEXEC.BAT Windows 95 created “The Registry” Windows 95 created “The Registry”  two dimensional structure for user and system information  principles extended in Windows NT v4 system and user settings downloadable to local registry across the networksystem and user settings downloadable to local registry across the network

14. Viewing/Editing the Registry REGEDT32 from command prompt… REGEDT32 from command prompt…  look but don’t touch!  contents should not be changed manually unless you really know what you are doing!!! Registry data that is loaded into memory can also be overwritten by data: Registry data that is loaded into memory can also be overwritten by data:  from local profiles  downloaded across the network…

15. Domains Microsoft name for network infrastructure universally known as LANs Microsoft name for network infrastructure universally known as LANs Similar to Internet use of “domain names” and DNS Similar to Internet use of “domain names” and DNS Domain can be serviced by a number of servers Domain can be serviced by a number of servers  can be dedicated for particular purposes  support very many users

16. Logon to Network Once the operating system has been loaded… Once the operating system has been loaded…  user logon screen presented Rapid local boot is fine… Rapid local boot is fine…  but most organisational computers are on networks… why?why?  why does network logon take so long?

17. “Policies”: Controlling User and System Settings The Windows user’s desktop is controlled with policies The Windows user’s desktop is controlled with policies  user policies  system policies Configuring and using policies - essential part of any network administrator’s job! Configuring and using policies - essential part of any network administrator’s job!  could be 100s or 1000s of systems, & users

18. System Settings For configuration of hardware and software For configuration of hardware and software  different types of system need different settings  system settings for a given computer may need to be changed for particular users e.g. to change screen refresh rate for epileptics

19. User Settings More a matter of convenience for the user More a matter of convenience for the user  mandatory profiles users all get the same desktop settings!users all get the same desktop settings! anything added is lost during logoff!anything added is lost during logoff!  roaming profiles - desktop settings preserved between user sessions saved across the network…saved across the network…

20. What is The Registry? A hierarchical store of system and user settings A hierarchical store of system and user settings Five basic subtrees: Five basic subtrees:  HKEY_LOCAL_MACHINE : local computer info. Does not change no matter which user is logged on  HKEY_USERS : default user settings  HKEY_CURRENT_USER : current user settings  HKEY_CLASSES_ROOT : software config data  HKEY_CURRENT_CONFIG : “active” hardware profile Each subtree contains one or more subkeys… Each subtree contains one or more subkeys…

21. Location of the Windows Registry In XP… In XP…  c:\windows\system32\config folder Six files (no extensions): Six files (no extensions):  Software  System – hardware settings  Sam, Security not viewable through regedt32not viewable through regedt32  Default – default user  Sysdiff – HKEY USERS subkeys  Also to be considered: ntuser.dat user settings that override default useruser settings that override default user

22. Emergency Recovery if Registry lost or badly damaged Backup registry files created during text-based part of windows installation Backup registry files created during text-based part of windows installation  also stored in: c:\windows\system32\configc:\windows\system32\config have.sav suffixhave.sav suffix  only updated if “R” option is chosen during a windows recovery/reinstall NEVER UPDATED backup is saved to NEVER UPDATED backup is saved to  C:\windows\repair folder  no user and software settings  reboots back to “Windows is now setting up”

23. Backing up the Registry Much forgotten… an oversight that may later be much regretted!!! Much forgotten… an oversight that may later be much regretted!!!  can copy to tape, USB stick CD/DVD, or disk  rarely more than 100 Mb Two options; Two options;  Use third-party backup tool e.g http://www.acronis.co.uke.g http://www.acronis.co.ukhttp://www.acronis.co.uk  Use windows “backup” not recommended by experts!not recommended by experts! but already there & does work!but already there & does work! to copy the registry if this tool is chosen, a “system state” backup option should be selectedto copy the registry if this tool is chosen, a “system state” backup option should be selected

24. System Policy File A collection of registry settings downloaded from the domain controller during logon A collection of registry settings downloaded from the domain controller during logon Can apply different system settings to a computer, depending on the user or group logging on Can apply different system settings to a computer, depending on the user or group logging on Can overwrite: Can overwrite:  local machine registry settings  current user registry settings Should therefore only be used by those who know what they are doing!!! Should therefore only be used by those who know what they are doing!!!

25. System Policy File Saved as NTCONFIG.POL Saved as NTCONFIG.POL Normally held on Domain Controllers Normally held on Domain Controllers  read by local machine during logon procedure  provides desktop settings, and therefore used to control aspects of appearance of the desktop Different NTCONFIG.POL settings can be applied according to: Different NTCONFIG.POL settings can be applied according to:  User  Group  Computer Users with roaming profiles additionally save desktop settings to their profile folders Users with roaming profiles additionally save desktop settings to their profile folders

26. Characteristics of Microsoft “domains” Not the same as DNS domains Not the same as DNS domains Really just another way of saying LAN or client-server network Really just another way of saying LAN or client-server network Server controlled Server controlled  but server needs to be elevated to domain controller status  needs to install “DNS server”

27. Domains and Active Directory Active Directory… Active Directory…  logically connects servers together  servers create domains…  can use connections between servers to model the DNS system on a Microsoft network But things can go wrong… But things can go wrong…  knowledge of DNS servers required

28. Internet Domain Naming An attempt to give logical names to computers directly hooked up to the Internet An attempt to give logical names to computers directly hooked up to the Internet First defined back in 1983, through three early RFCs… First defined back in 1983, through three early RFCs…  881: The Domain Names Plan and Schedule (revised, 897, 921)  882: CONCEPTS and FACILITIES (revised, 1034)  883: IMPLEMENTATION and SPECIFICATION (revised, 1035)

29. The DNS System First defined in RFC 1101: First defined in RFC 1101: n “DNS Encoding of Network Names and Other Types” First recognisable as x.y.z format through RFC 1183: First recognisable as x.y.z format through RFC 1183: “New DNS RR Definitions ” “New DNS RR Definitions ” Explained including IANA (administration of first level domains) through RFC 1591 (1994) Explained including IANA (administration of first level domains) through RFC 1591 (1994) “Domain Name System Structure and Delegation” “Domain Name System Structure and Delegation”

30. DNS and DNS Zones The DNS system is hierarchical The DNS system is hierarchical A DNS Zone is defined as: A DNS Zone is defined as: “… a portion of the global Domain Name System (DNS) namespace for which administrative responsibility has been delegated”  it refers to the lower level domains logically connected to any one particular root domain (e.g..us or.com) z ay x DNS entry x.y.z DNS Zone: z Computers within z zone: a, x and y

31. Naming a Server within a DNS Zone Windows 2003 Servers promoted to domain controllers are assumed to be part of the DNS Windows 2003 Servers promoted to domain controllers are assumed to be part of the DNS  named accordingly within a hierarchy of domain names  DNS Server needs to be installed at this point… assists Active Directory with domain name record keepingassists Active Directory with domain name record keeping provides options for storing DNS/IP address pairsprovides options for storing DNS/IP address pairs

32. WINS, DNS, and IP addressing Older versions of Windows used “Windows Internet Naming Service” Older versions of Windows used “Windows Internet Naming Service”  look up service including NetBIOS names and corresponding IP addresses Now, DNS is increasingly replacing WINS: Now, DNS is increasingly replacing WINS:  DNS server manages access to network name/IP address look up

33. Managing Domain Users Active Directory installed when server promoted to domain controller Active Directory installed when server promoted to domain controller Users gain access via client machines Users gain access via client machines  to even enable user log on, a client machine must have an account in that domain  client details stored in active directory User must have a domain account User must have a domain account  details stored in “Active Directory”…  entry in database of usernames/passwords essential for successful login match

34. Potential Installation Traps & Errors Quite a lot of hardware has to be correctly configured Quite a lot of hardware has to be correctly configured Not plug-and-play? Not plug-and-play?  need to install software manually Not on the HCL? Not on the HCL?  Need to get drivers from the manufacturer & install from separate media All these potential problems can prevent installation from proceeding to completion All these potential problems can prevent installation from proceeding to completion

35. Potential Installation Traps & Errors The most common problem post- installation is that files become corrupt The most common problem post- installation is that files become corrupt This will mean that the system boot up process will be suspended indefinitely as the system looks in vain for the missing file This will mean that the system boot up process will be suspended indefinitely as the system looks in vain for the missing file

36. Correcting Installation Errors Each NOS should have a system to allow recovery from a failed installation Each NOS should have a system to allow recovery from a failed installation  With Windows 2000/3, it is “recovery console” Such a “recovery” system should allow the system to reboot to at least a command prompt Such a “recovery” system should allow the system to reboot to at least a command prompt  allowing the necessary file(s) to be re-installed… The computer should then again boot up satisfactorily The computer should then again boot up satisfactorily

37. Installing Clients Will be necessary if: Will be necessary if:  Existing client software not compatible with server-side or is upgraded for other reasons  Existing client software becomes faulty or will not connect to the domain  New computer to be added to the domain

38. Automatic Installations The first server on the network should always be installed manually The first server on the network should always be installed manually However, NOSs allow capabilities for the “automatic” installation of clients However, NOSs allow capabilities for the “automatic” installation of clients This means that all the questions that are asked by the installation process must be answered on a text file or “script” that can be accessed during the automatic install This means that all the questions that are asked by the installation process must be answered on a text file or “script” that can be accessed during the automatic install  with Windows 2000/3 this is known as UNATTEND.TXT