1. COMP2221 Networks in Organisations Richard Henson February 2013

2. Week 4: Some Important Network Operating Systems Objective: Objective:  Name significant network operating systems in developments towards today’s/tomorrows organisational networks  Briefly explain features of a typical network operating system (server end & client end)  Explain a (network) operating system architecture in terms of a multi-layered model

3. What are Operating Systems? Bundle of Software! Bundle of Software!  many programs working together Used to make the computer function Used to make the computer function  control of hardware  platform to support applications including user interfaceincluding user interface  utilities to control the platform e.g. disk/file managemente.g. disk/file management

4. Software Layers and Operating Systems os kernel CPU, motherboard Operating system functions & user interface Applications

5. What if the Operating System has software faults? The platform becomes “unstable”!! The platform becomes “unstable”!! Could be errors in Could be errors in  hardware control?  user interface?  utilities? What would happen to: What would happen to:  applications running on a poorly designed platform?  businesses depending on such apps?

6. Software Faults & CWE Mitre: classified fault types into a Common Weakness Enumeration (CWE) Mitre: classified fault types into a Common Weakness Enumeration (CWE)  community developed, formal list of software weakness types Use of CWE: Use of CWE:  common language for describing software weaknesses in architecture, design, or code [TSI/2012/183] © Copyright 2003-2012 6

7. More about CWE Currently 810 distinct CWE entries identified!! Currently 810 distinct CWE entries identified!!  more commonly encountered weaknesses usually “repeat offenders” CWE provides: CWE provides:  standard measuring stick for software tools targeting software weaknesses  common baseline standard for efforts to identify, mitigate, and prevent software weaknesses

8. CWE Top 25 faults (1) Rank IDName 1CWE-79Failure to Preserve Web Page Structure ('Cross-site Scripting') 2CWE-89Improper Sanitization of Special Elements used in an SQL Command ('SQL Injection') 3CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') 4CWE-352Cross-Site Request Forgery (CSRF) 5CWE-285Improper Access Control (Authorization) 6CWE-807Reliance on Untrusted Inputs in a Security Decision 7CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') 8CWE-434Unrestricted Upload of File with Dangerous Type 9CWE-78Improper Sanitization of Special Elements used in an OS Command ('OS Command Injection') 10CWE-311Missing Encryption of Sensitive Data 11CWE-798Use of Hard-coded Credentials 12CWE-805Buffer Access with Incorrect Length Value 13CWE-98Improper Control of Filename for Include/Require Statement in PHP Program ('PHP File Inclusion') [TSI/2012/183] © Copyright 2003-2012

9. CWE Top 25 faults (2) RankIDName 14CWE-129Improper Validation of Array Index 15CWE-754Improper Check for Unusual or Exceptional Conditions 16CWE-209Information Exposure Through an Error Message 17CWE-190Integer Overflow or Wraparound 18CWE-131Incorrect Calculation of Buffer Size 19CWE-306Missing Authentication for Critical Function 20CWE-494Download of Code Without Integrity Check 21CWE-732Incorrect Permission Assignment for Critical Resource 22CWE-770Allocation of Resources Without Limits or Throttling 23CWE-601URL Redirection to Untrusted Site ('Open Redirect') 24CWE-327Use of a Broken or Risky Cryptographic Algorithm 25CWE-362Race Condition [TSI/2012/183] © Copyright 2003-2012

10. Software Weakness Mitigation What to do about all these faults….? What to do about all these faults….? Many concepts and practices needed for Trustworthy Software have existed for many years… Many concepts and practices needed for Trustworthy Software have existed for many years…  “Due Diligence”  Pareto 80:20 [TSI/2012/183] © Copyright 2003-2012 10

11. Due Diligence  Implies software should be reasonably trustworthy…. what does “reasonably” mean?what does “reasonably” mean?  Implementations vary with Audiences and Assurance Requirements

12. Pareto 80:20 (favoured by TSI)  Iteratively using existing experience  Interpreting for common good  Example: switching on and acting on Compiler Warning Flags…switching on and acting on Compiler Warning Flags… obviates many common “repeat offender” weaknessesobviates many common “repeat offender” weaknesses If only this was normal practice!!! If only this was normal practice!!!

13. 2011 Vulnerabilities from Major Vendors [TSI/2012/183] © Copyright 2003-2012

14. Apps and Operating Systems Applications need a platform… Applications need a platform…  better designed platform…? easier to design trustworthy appseasier to design trustworthy apps Mobile phone app vulnerabilities by malware for platform (F-Secure, 2012): Mobile phone app vulnerabilities by malware for platform (F-Secure, 2012):  http://www.f-secure.com/static/doc/labs_global/Research/Mobile%20Threat%20Report%20Q3%202012.pdf http://www.f-secure.com/static/doc/labs_global/Research/Mobile%20Threat%20Report%20Q3%202012.pdf  Apple iOS: 1.1  Symbian: 29.8  Android: 62.8  Windows mobile: 0.6

15. Why the differences? Apps written to use operating system (os) platform appropriately… Apps written to use operating system (os) platform appropriately…  well designed os restricts/prevents inappropriate use  poorly designed os allows sloppy habits but may have performance advantages… (!)but may have performance advantages… (!) e.g. Android top 25 vulnerabilities (CVE):e.g. Android top 25 vulnerabilities (CVE): n http://www.cvedetails.com/vulnerability-list/vendor_id-1224/product_id- 19997/Google-Android.html http://www.cvedetails.com/vulnerability-list/vendor_id-1224/product_id- 19997/Google-Android.html http://www.cvedetails.com/vulnerability-list/vendor_id-1224/product_id- 19997/Google-Android.html

16. Early Operating Systems Each of the early computers was unique Each of the early computers was unique  each had to have its own purpose-built operating system IBM: world’s first mass produced “mainframe” IBM: world’s first mass produced “mainframe”  IBM 701 (1952) purchasers expected to write their the operating system themselves!purchasers expected to write their the operating system themselves! first “mass produced” operating system written by General Motors: GM-NAA I/O in 1956first “mass produced” operating system written by General Motors: GM-NAA I/O in 1956 n adopted by IBM as IBSYS  IBM hugely successful; by 1980s, allegedly bigger than US government (?)

17. First British Operating system Leo 3 was the first mass produced British Computer Leo 3 was the first mass produced British Computer  94 units built 1961-1969 full list of buyers http://www.leo- computers.org.uk/newleo3s.htmfull list of buyers http://www.leo- computers.org.uk/newleo3s.htmhttp://www.leo- computers.org.uk/newleo3s.htmhttp://www.leo- computers.org.uk/newleo3s.htm  each had a loudspeaker connected to the CPU… so operators could tell if it was “looping”  had a multi-tasking operating system called “master program” Some continued in service until 1981 Some continued in service until 1981

18. First Minicomputer & Operating system Produced by Digital Equipment Corporation (DEC) in 1963 Produced by Digital Equipment Corporation (DEC) in 1963  called the PDP-6 “mini” in size compared to mainframes“mini” in size compared to mainframes huge by today's standardshuge by today's standards  operating system called “monitor” evolved into the TOPS10 (1970)evolved into the TOPS10 (1970) ran on the legendary PDP-10ran on the legendary PDP-10 still going until 1988still going until 1988 can get it even now:can get it even now: http://www.inwap.com/pdp10/96license.txthttp://www.inwap.com/pdp10/96license.txthttp://www.inwap.com/pdp10/96license.txt

19. Unix Spin-off (1969) from project MULTICS Spin-off (1969) from project MULTICS  First attempt at a multiuser operating system Consortium including Bell Labs, AT&T,Consortium including Bell Labs, AT&T, n US equivalent of BT at that time FAILED! Too ambitious…FAILED! Too ambitious…  Bell Labs: cut down derivation called UNICS -> UNIX written in assembly language by Ken Thompsonwritten in assembly language by Ken Thompson sharing of processes also being explored in The ARPAnet projectsharing of processes also being explored in The ARPAnet project Commercial Challenge:Commercial Challenge: DEC PDP-7 minicomputerDEC PDP-7 minicomputer needed a general purpose “time sharing” operating system for multiuser use…needed a general purpose “time sharing” operating system for multiuser use… their own os “monitor” had not yet matured into TOPS-10their own os “monitor” had not yet matured into TOPS-10

20. Thompson, Ritchie, “B”, NB, “C” & Unix Thompson looking for a high-level language to develop a time sharing os Thompson looking for a high-level language to develop a time sharing os briefly toyed with Fortranbriefly toyed with Fortran worked with colleague Dennis Ritchie to create their own higher level language – “B”, based on BCPLworked with colleague Dennis Ritchie to create their own higher level language – “B”, based on BCPL http://cm.bell-labs.com/cm/cs/who/dmr/kbman.htmlhttp://cm.bell-labs.com/cm/cs/who/dmr/kbman.htmlhttp://cm.bell-labs.com/cm/cs/who/dmr/kbman.html development of B = newB (NB)development of B = newB (NB) development of NB -> Cdevelopment of NB -> C Unix kernel was rewritten in “C” (1973)Unix kernel was rewritten in “C” (1973)

21. Development of Unix/C “C” compiler completed by Ritchie in 1972 “C” compiler completed by Ritchie in 1972 Further commercial Unix versions (for Honeywell & IBM) released in 1973 Further commercial Unix versions (for Honeywell & IBM) released in 1973 “C” further developed during 1973-7 “C” further developed during 1973-7 Full definition of language as Kernighan & Ritchie “C” (1978) Full definition of language as Kernighan & Ritchie “C” (1978)  rapidly gained universal acclaim Unix still written in “C” to present day! Unix still written in “C” to present day!  32-bit processing from the outset

22. Open Sourceness of Unix AT&T not allowed to be a commercial companyAT&T not allowed to be a commercial company could not sell Unixcould not sell Unix gave a copy away free to any developer who wanted to use it!gave a copy away free to any developer who wanted to use it! many universities contributed to its developmentmany universities contributed to its development Result (in 1979): Unix version 7Result (in 1979): Unix version 7 still recognisable today!still recognisable today!

23. Silicon Valley, TCP/IP and Unix University of California created The ARPAnet (1969)University of California created The ARPAnet (1969) 1975 onwards: Berkeley, north of San Francisco1975 onwards: Berkeley, north of San Francisco hub for its own unique brand of Unix developmentshub for its own unique brand of Unix developments start of “Silicon Valley” (IT hot spot around SF)start of “Silicon Valley” (IT hot spot around SF) ARPAnet teamARPAnet team developed TCP/IPdeveloped TCP/IP 1980, gained approval through RFC1980, gained approval through RFC operating system that would support TCP/IP arrived in 1983…operating system that would support TCP/IP arrived in 1983… Berkeley Unix (v4.2) packaged with TCP/IP protocol stackBerkeley Unix (v4.2) packaged with TCP/IP protocol stack Sun Microsystems producing the hardware…Sun Microsystems producing the hardware…

24. Bell Labs Unix becomes Commercial… US Dept of Justice broke up AT&T in 1984US Dept of Justice broke up AT&T in 1984 Bell Labs then allowed to sell their Unix source code…Bell Labs then allowed to sell their Unix source code… Fortunately for SCO (Santa Cruz Operations) they had ported Bell Unix to Intel hardware the previous year (!)Fortunately for SCO (Santa Cruz Operations) they had ported Bell Unix to Intel hardware the previous year (!) SCO Unix for PC became a lucrative business marketSCO Unix for PC became a lucrative business market operating system provided security on a PC where DOS couldn’t…operating system provided security on a PC where DOS couldn’t…

25. Bad days for Unix… Unix free by nature from outset Unix free by nature from outset  not so on an Intel PC, thanks to SCO!!!  Bell Labs jealously guarded the source code…  universities lost interest Unix became expensive to buy… and was still not user-friendly or easy to use so even more expensive to own! Unix became expensive to buy… and was still not user-friendly or easy to use so even more expensive to own!

26. Linux From 1992 (Linus Torvalds, University of Helsinki) made free Unix possible again! From 1992 (Linus Torvalds, University of Helsinki) made free Unix possible again!  LINUX – based on his name… Took… Took…  Stallman’s GNU open source Unix which Tanenbaum had developed into MINIX…which Tanenbaum had developed into MINIX…  very stable  secure file system  very efficient, optimised code  earlier versions ran on an Intel 486! Still Unix, still a server-end system Still Unix, still a server-end system  for client-server networking, need client-end software: e.g. Banyan VINESe.g. Banyan VINES

27. Linux Still freely available via Internet! Still freely available via Internet! Huge range of software tools for managing UNIX networks available for download Huge range of software tools for managing UNIX networks available for download Problems (compared to Windows): Problems (compared to Windows):  not as easy to manage  limited on-screen help  limited range of good application software  not all hardware has UNIX/LINUX driver software

28. Linux for Mobile Variety of platforms: Variety of platforms:  Symbian  Android If Linux is so good re trustworthiness & security, why is Android so bad??? If Linux is so good re trustworthiness & security, why is Android so bad???

29. Operating Systems for PC Ethernet Networks Original Topology (1980s, early 90s): Original Topology (1980s, early 90s):  bus, coaxial cable & BNC connectors (!) DOS? DOS?  No way! not designed for: server end stuffserver end stuff distributed communicationsdistributed communications security…security…

30. Windows Server Developments since 2000 2003 Server 2003 Server  more improvements to active directory  64-bit version available! 2008 Server 2008 Server  file system enhancements  active directory: directory tree extendeddirectory tree extended better management tools (larger networks)better management tools (larger networks) Although Bill Gates may have retired, Steve Cutler is still with them (helped with “Azure” and now…Xbox) Although Bill Gates may have retired, Steve Cutler is still with them (helped with “Azure” and now…Xbox)  http://www.amd.com/us- en/assets/content_type/DownloadableAssets/Micr osoft_Video_Statement.wmv http://www.amd.com/us- en/assets/content_type/DownloadableAssets/Micr osoft_Video_Statement.wmv http://www.amd.com/us- en/assets/content_type/DownloadableAssets/Micr osoft_Video_Statement.wmv

31. Client-side Developments… Microsoft Domination… Microsoft Domination…  XP: finished off the evolution from Windows 95/98  Vista: mainly a desktop change not universally appreciated!not universally appreciated! mobile devices started to have:mobile devices started to have: n CPUs & operating systems (!) n user interfaces & use apps… Reaction to Vista… Reaction to Vista…  Apple became popular  other “mobile” desktops became popular Windows 7 stopped the rot… Windows 7 stopped the rot… Windows Mobile: good platform for apps Windows Mobile: good platform for apps  but Windows client-end dominance lost for good…

32. So, which Server operating system would the larger company use today? IBM, or other “mainframe”? IBM, or other “mainframe”?  why not? Windows 2008 very popular with finance industry & previous IBM customers! Windows 2008 very popular with finance industry & previous IBM customers! Unix (incl Linux) popular with previous DEC customers Unix (incl Linux) popular with previous DEC customers  still cheaper than Windows  still more complicated, but suits companies that value and develop technologies

33. And the small business? Lot of contradictory advice Lot of contradictory advice  use Linux!? Windows? Apple?  Don’t bother? use virtualisationuse virtualisation OutsourceOutsource  Don’t bother with… clients? servers? use The Clouduse The Cloud BYOD (mostly users own smartphones)?BYOD (mostly users own smartphones)? Who should they listen to? Why? Who should they listen to? Why?

34. And os platforms for tomorrow? Need to plan ahead… Need to plan ahead…  crucial if involved in procurement for and management of networks  investment could be expected to last 5 years!  next Windows/AppleOS/Unix/Linux?  others? will servers be “old hat”? Will all clients be “dumb”? Time to do a little research... Time to do a little research...

35. History: Operating Systems for PC Ethernet Networks  two popular client-server operating systems emerged: Novell NetwareNovell Netware n IPX/SPX protocol n not OSI compliant - proprietary & code secret DEC (Digital) PCSADEC (Digital) PCSA n DECnet protocol n OSI & TCP/IP compliant - code open source

36. Netware - late 1980s Novell’s proprietary IPX/SPX network protocol Novell’s proprietary IPX/SPX network protocol  network naming based on MAC address hardwired into network card during manufacturehardwired into network card during manufacture Also, MHS protocol for message- handling and email within the LAN Also, MHS protocol for message- handling and email within the LAN

37. Novell Netware Cool Server stuff… Cool Server stuff…  secure file system based on user, groups, rights & inherited rights  supported mirroring, duplexing, RAID  TTS to reverse incomplete transactions  network resource names, etc. stored as a separate bindery on each server

38. Other Features of Netware I/O optimisation: I/O optimisation:  disk caching  elevator seeking (disk accesses ordered according to position on disk)  directory hashing

39. Strengths of Netware  Fast MAC address not IP, fewer headers, less processing of packetsMAC address not IP, fewer headers, less processing of packets  Secure awarded US gov Server Fault Tolerance (SFT) grade IIIawarded US gov Server Fault Tolerance (SFT) grade III n when used with server duplexing

40. Enduring Problems with Netware Only ran on Intel Platform Only ran on Intel Platform Reliant on DOS/Windows at the client end Reliant on DOS/Windows at the client end NDS (Directory Structure) not X500 compliant NDS (Directory Structure) not X500 compliant Not directly compatible with TCP/IP Not directly compatible with TCP/IP  interprocess communication based on IPX/SPX  used MAC addresses (fixed on network card) as unique identifiers, rather than IP addresses Not suitable for peer-peer networking Not suitable for peer-peer networking Not pre-emptive in handling processes Not pre-emptive in handling processes

41. What happened to Netware? V.successful in early 1990s V.successful in early 1990s  better sales than DEC PCSA architecture, even though the latter was OSI compliant (!!) SPX/IPX faster than TCP/IP…SPX/IPX faster than TCP/IP…  70% of the PC network market

42. What happened to Netware Didn’t see what was coming (Microsoft!)… Didn’t see what was coming (Microsoft!)…  DEC mini computers lost market share everyone wanted a PC networkeveryone wanted a PC network main LAN rival DEC was being sold off and “asset stripped”main LAN rival DEC was being sold off and “asset stripped” future looked brightfuture looked bright  BUT… by 1998, Novell Netware sales were sunkby 1998, Novell Netware sales were sunk by 2000, even Oracle stopped supporting themby 2000, even Oracle stopped supporting them only kept in business by merging with Red Hat Linuxonly kept in business by merging with Red Hat Linux

43. More on DEC (Digital Equipment) World’s most innovative computer company for many years… World’s most innovative computer company for many years…  as already stated - first minicomputer: PDP-1 (Programmable Data Processor)PDP-1 (Programmable Data Processor)  first UNIX/C implementation On PDP-5On PDP-5

44. DEC continued… Most successful minicomputer: Most successful minicomputer:  VAX (Virtual Address eXtension) First virtual memory operating system First virtual memory operating system  VMS (virtual memory system) for VAX First commercially successful RISC chip First commercially successful RISC chip  alpha First commercial Internet domain & website First commercial Internet domain & website First successful search engine: AltaVista First successful search engine: AltaVista

45. Organisational Networks in 1990 Business/finance companies: Business/finance companies:  usually IBM networks Science/Technology/Engineering companies: Science/Technology/Engineering companies:  usually DEC networks Smaller companies (SME size...) Smaller companies (SME size...)  couldn’t justify/afford networks!

46. Where did DEC go? Second biggest computer company in the world in 1990! Second biggest computer company in the world in 1990!  over 100000 employees!  with early 90s recession, went into decline… New MD in 1992, only accelerated the decline New MD in 1992, only accelerated the decline  assets sold one by one… unkindest cut – alpha chip to Intel in 1997unkindest cut – alpha chip to Intel in 1997  what was left (VMS) went to Compaq in 1998 sold on to HP…sold on to HP…

47. What happened? As with the downfall of IBM, Netscape and Novell… As with the downfall of IBM, Netscape and Novell…  out-manoeuvred in business  perhaps the name Microsoft might help…

48. Microsoft and VMS… Now long enough ago to be of historical interest… Now long enough ago to be of historical interest…  Dave Cutler, brains behind DEC’s VMS; http://en.wikipedia.org/wiki/Dave_Cutler http://en.wikipedia.org/wiki/Dave_Cutlerhttp://en.wikipedia.org/wiki/Dave_Cutler  went to work at Microsoft in 1988 to develop “a new operating system” (NT)…to develop “a new operating system” (NT)… DEC watching their mini-computers become “dinosaurs” (1990-93) DEC watching their mini-computers become “dinosaurs” (1990-93)  pinned hopes on new RISC chip (alpha)  keen to get their alpha chip onto the original Windows NT…

49. A tale of intellectual copyright (and smart business) DEC saw NT as their big opportunity to get into the PC server business DEC saw NT as their big opportunity to get into the PC server business  expected Alpha chip platform/Windows NT to be popular  signed away rights to Cutler & co’s code – code used in creating windows NT Microsoft effectively got the technologies behind VMS that they used for NT… for free!!!!Microsoft effectively got the technologies behind VMS that they used for NT… for free!!!! final insult… Intel platform preferred for servers (!)final insult… Intel platform preferred for servers (!) Thanks to HP, and enthusiastic users, VMS lives (!) Thanks to HP, and enthusiastic users, VMS lives (!)  available for download at: http://www.openvms.compaq.com/openvms/freewarehttp://www.openvms.compaq.com/openvms/freewarehttp://www.openvms.compaq.com/openvms/freeware

50. Microsoft & Network Operating Systems Whilst the US government was being defeated in the courts by IBM… Whilst the US government was being defeated in the courts by IBM…  a deal that almost put them out of business was pulled off by the young Bill Gates!  story about IBM negotiations with Bill Gates (regarding his mate Tim Paterson’s os): http://inventors.about.com/library/weekly/aa033099.htmhttp://inventors.about.com/library/weekly/aa033099.htmhttp://inventors.about.com/library/weekly/aa033099.htm  and the tragedy of Gary Kildall (creator of CP/M, main rival to DOS & one time business partner of Steve Jobs)… http://www.businessweek.com/magazine/content/04_43/b3 905109_mz063.htmhttp://www.businessweek.com/magazine/content/04_43/b3 905109_mz063.htmhttp://www.businessweek.com/magazine/content/04_43/b3 905109_mz063.htmhttp://www.businessweek.com/magazine/content/04_43/b3 905109_mz063.htm

51. DOS (Desktop Operating System) As was to be expected from a back-street deal… As was to be expected from a back-street deal…  DOS was an awful operating system…  no way it could be satisfactorily used for even multi-tasking, let alone networking…  no way of logging in as an authenticated user…logging in as an authenticated user… restricting access to resources…restricting access to resources…  to the new (misguided?) computer generation… none of this matterednone of this mattered  by the late 1980s Gates was the 4 th richest person in the world!

52. OS2, Windows, and Windows NT By late 1980s, PCs being used for serious business purposes By late 1980s, PCs being used for serious business purposes  IBM needed a serious operating system for the PC…  Microsoft worked them on OS2  still didn’t see Gates as a rival! At about the same time… At about the same time…  Cutler left DEC… joined Microsoft  scope for a virtual memory operating system… (Windows)(Windows)

53. Windows On the one hand On the one hand  Microsoft were working with IBM on OS2 One the other hand: One the other hand:  they were working on developing Windows and working with software developers to provide applications for Windows…and working with software developers to provide applications for Windows… n users want apps, not operating systems! Guess which one won??? Guess which one won???  you’ve got it… Microsoft now bigger than IBM

54. Windows NT Windows… based on DOS Windows… based on DOS  virtual memory enabled multitasking  but architecture fundamentally flawed… Stopgap while new “serious” operating system being developed… Stopgap while new “serious” operating system being developed… using DEC technology…using DEC technology…  “New Technology” operating system quietly released in 1993  as a disguised front end enhancement to Windows 3.1  known as Windows 3.11 (for workgroups)

55. NT Architecture Industry experts soon noticed that many features were surprisingly similar to VMS… Industry experts soon noticed that many features were surprisingly similar to VMS…  oddity… VMS + 1 = WNT (!!) But Microsoft’s customers were from a new generation. The commercial desktop product was still basically DOS, but Gates now offered But Microsoft’s customers were from a new generation. The commercial desktop product was still basically DOS, but Gates now offered  peer-peer networking and a simple network protocol (NETBEUI)  user-friendly graphical interface  sharing resources on apps  even TCP/IP compatibility…

56. Flexibility of Windows NT (followed the Unix pattern) Operating system kernel hardware Operating system functions & interface Applications

57. Windows NT v Unix v Netware By 1994, three possible network platforms: By 1994, three possible network platforms:  Novell: fast, proven, scalable, well established, but proprietary (NDS & IPX/SPX)  Unix: robust, scalable, open source & Internet ready but complex, & limited apps  Windows NT: neither robust nor scalable but Gates by now a past master at exploiting weakness... (!)but Gates by now a past master at exploiting weakness... (!)

58. Progressive Development of Windows NT os kernel (diff versions of NT available for diff CPUs) range of CPUs, motherboards Operating system functions & interface (Windows) Applications (Windows apps -> NT apps)

59. NT version 4 Released late 1996 Released late 1996  Windows 95 interface & registry  many www features, incl. IIS (web server) Server end: Server end:  designed to support server applications no theoretical limit to number of usersno theoretical limit to number of users  now became a major challenge to Netware (not TCP/IP compatible) & Unix (still not enough apps)  main problem: not scalable

60. The 32-bit Windows NT architecture Secure 32-bit kernel based on VMS Secure 32-bit kernel based on VMS  remains intact to present day  now enhanced to 64-bit (but this was supposed to happen originally with “Windows 5”, to support DECs 64-bit alpha-chip(but this was supposed to happen originally with “Windows 5”, to support DECs 64-bit alpha-chip Separated kernel provided the capability for NT, like Unix, to run on multiple platforms Separated kernel provided the capability for NT, like Unix, to run on multiple platforms  guess who didn’t like that idea!

61. Windows NT Architecture Supports pre-emptive multitasking & multithreading Supports pre-emptive multitasking & multithreading  good for centralised control Secure file system (NTFS) Secure file system (NTFS) Applications have separate address spaces (unlike DOS/Windows… crash!) Applications have separate address spaces (unlike DOS/Windows… crash!)  up to 4 Gb of memory  up to 16 Eb of disk space (1Eb = 2 60 bytes)

62. NT architecture (continued) Server products have scope for huge additional functionality… Server products have scope for huge additional functionality…  offered as services Problems: Problems:  much code outside the kernel was new; bugs had to be ironed out  each server had its own security database; considerable problems for scalability

63. Windows 2000 The big one!!! The big one!!!  Designed to merge: peer-peer networking capabilities of Windowspeer-peer networking capabilities of Windows client-server requirements of LANsclient-server requirements of LANs Microsoft technologies with Internet technologiesMicrosoft technologies with Internet technologies  Yet could still work with “DOS-based” i.e. Windows 3.x/95/98 clients Microsoft’s own “history of Windows” (client- end/desktop versions):Microsoft’s own “history of Windows” (client- end/desktop versions): n http://www.microsoft.com/windows/winhistorydesktop.mspx http://www.microsoft.com/windows/winhistorydesktop.mspx http://www.microsoft.com/windows/winhistorydesktop.mspx

64. Windows 2000 et seq… Scalable Scalable  Active Directory X500 compliant directory serviceX500 compliant directory service even developed with aid of RFCseven developed with aid of RFCs multiple domainsmultiple domains enterprise-wide security & resource-sharingenterprise-wide security & resource-sharing  arguably much better than NDS finished off Novell Netware…finished off Novell Netware…

65. Windows 2000 et seq… Secure… (!) Secure… (!)  secure remote authentication with help from Active Directory…with help from Active Directory…  Kerberos (IETF, RFCs)  PKI-ready (IETF, RFCs)  terminal services remote log on with minimal computing resourcesremote log on with minimal computing resources

66. More Recent OS Developments Novell survived (as a company) by: Novell survived (as a company) by:  merging with developers of Linux  continuing to support “legacy” Netware systems HP kept VMS customer base… HP kept VMS customer base…  once DEC alpha chip was history, developed new Intel-based hardware platform (Integrity) to interface with VMS kernel Linux (very) slowly gaining popularity… Linux (very) slowly gaining popularity…