1. Linux-vs-Windows Security
Operating System
Security
Linux-vs-Windows Security
Erik P. Friebolin

2. Security in Operating Systems
Security Breaches
Security Goals
Protected Objects of the general purpose OS
Protection of Objects

3. Security Breaches Exposure Vulnerability Threats
A form of possible loss or harm in a computing system.
Vulnerability
Weakness that might be exploited to cause loss or harm.
Threats
Circumstances that have the potential to cause loss or harm.

4. Types of Threats
Interruption
Interception
Modification
Fabrication

5. Security Goals Confidentiality Integrity Availability
The assets of a computing system are accessible only by authorized parties.
Integrity
Assets can be modified only by authorized parties or only in authorized ways.
Availability
Assets are accessible to authorized parties.

6. Protection in General-Purpose OS
Protected Objects and Methods
Protecting Memory and Addressing
Protecting Access to General Objects
File Protection Mechanisms
User Authentication

7. Protected Objects and Methods
Memory
Sharable I/O devices, such as disks
Serially reusable I/O devices, such as printers
Sharable programs and sub-programs
Sharable data

8. Protected Objects and Methods
Security Methods
Seperation: keeping one user’s objects separate from other users’
Physical Seperation
Temporal Seperation
Logical Seperation
Cryptographic Seperation
Granularity of Control
The larger the level of the object controlled, the easier it is to implement access control.

9. Protecting Memory and Addressing
Fence
Relocation
Base/Bounds Registers
Tagged Architecture
Segmentation
Paging

10. Protecting Access to General Objects
Memory
A file or data on an auxiliary storage device
An executing program in memory
A directory of files
A hardware device
A table of the operating system
Passwords
A data structure, such as a stack

11. Protecting Access to General Objects
Directory
OS maintains all directories. Each user has a list(directory) that contains all the objects that user is allowed to access.
Access Control List
Each object has an ACL. This list shows all subjects who should have access to the object and what the access is.

12. File Protection Mechanisms
Basic Forms of Protection
All-None Protection
Group Protecton
Single Permission
Password or other token
Temporary Acquired Permission

13. User Authentication Use of Passwords Attacks on Passwords
Password Selection Criteria
The Authentication Process

14. Linux Operating System
An OS initially created by Linus Torvolds (Finland) and a team working over the Internet.
Developed from MINIX, a small Unix system
An open and free operating system, adaptable to meet individual nees.

15. Windows Operating System
Developed by Microsoft Corporation
Windows OS first introduced in 1983
Windows 3.1 sold +10million copies – best selling GUI in computing history.
The most widely used GUI in the world today.

16. Linux Security Advantages Disadvantages
Security has had years to be tested and verified
Security is tied to a file
Ability to merge systems/domains
Firewall functionality built-in to server
Disadvantages
Limited file access control
Security not as strict
No Auditing

17. Windows Security Advantages Disadvantages Stricter security available
Greater control of access permissions.
Auditing of security events
Disadvantages
Security still in infancy
Most widely used software

18. QUESTIONS?

19. References
D. Denning, P. Denning, Certification of Programs for Secure Information Flow, CommACM, V20 N7, Jul 1977, pp
J. Linn, Practical Authentication for Distributed Computing, Proc IEEE symp Security & Privacy, IEEE Comp Soc Press 1990, pp
C.P. Pfleeger, Security in Computing, Prentice Hall, NJ, 1996
“The Great Linux-vs-NT Debate”, accessed 7/12/02