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Host and Application Security. Lesson 5: The Role of an OS. Environment. What is the output of a program?. Right… it’s all about the Environment. What is an operating system? How did Oses come about? Some examples and the security implications of them. Historically. Batched systems
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Host and Application Security Lesson 5: The Role of an OS
Environment • What is the output of a program?
Right… it’s all about the Environment • What is an operating system? • How did Oses come about? • Some examples and the security implications of them
Historically • Batched systems • Multiprogrammed Systems • Time sharing • Real-time systems
Services Provided • Essentially, a “resource allocator” • CPU time • Memory space • File storage space • IO… • Provides abstraction • What’s in there? • Everything the vendor ships • “the one program running at all times on the computer” (Silberschatz)
OS Architecture • Monolothic • Things are loaded into the operating system, and run with the privileges of the OS • Example: Linux • Microkernel • Take everything that you don’t need out and put it user mode • Example: Symbian • “Hybrid” Kernel • Some blending of the above • Example: Windows
Windows 7 • DOS: One program ruled all • Windows 3.1: Some kind of multitasking • Windows NT: A protected environment • Windows 95, 98, ME: Better separation, better multitasking, still based on DOS • Windows 2000: Based on NT 4 codebase • Windows XP: Possibly “most successful” Windows OS • Windows Vista: Added UAC, amongst other things • Windows 7: Lots of security enhancements
Unix • Source: Wikipedia