Topics for Final Exam
System Security
Hardware support
user-mode, kernel-node
segmentation -- base and limit
Encryption
RSA -- public key/private key for privacy and
authentication.
DES -- private key, symmetric key.
certificates
Kerberos authentication
Authorization model
ACL--access control lists
Capabilities list
Unix authorization for files
rwx for owner group and world
sticky bit
Vulnerabilities
Finger attack
Trojan horse
Brute force
Masquerading
Files Systems
File structures
FAT--file allocation table
inodes
sync system call
hard link and soft link
partitions and mounting file systems
organization of free lists
bad block list
contiguous block allocation (CDROM) and indexed blocks
File Structures
byte oriented files
Structured files and index-sequential access
Database servers
byte streams--stdin, stdout, stderr
sockets
File Types
Data, executable, relocatable segments
distinct from swap space.
Memory mapped files
File system management
open file tables
fork cause child to share opened files
File Services API
open, close, read, write, seek, IOCTL, pipes
Blocking/non-blocking reads and writes
Memory Management
Dynamic vs static memory management
working set principle
Optimal page replacement (Balady)
fifo, least recently used (LRU), least frequently used
(LFU)
clock algorithm approximation to LRU
computing page fault counts from memory reference streams
Stack algorithms
Virtual memory
virtual address -- physical address
pages and page frames
Memory management unit
multi-level page tables
Table look-aside buffer (TLB)
Segmentation
homogeneous segments
facilitates sharing with late binding
Deadlock
consumable vs. reusable resources
General model-- System state consists of directed graph where
nodes are Thread/processes and resources and edges indicate resource allocation,
processes waiting on a request, processes able to produce a consumable resource.
Transitions between states occur with: resource allocation, resource return, new
resource request, resource produced.
Deadlock definition and detection
Banker's algorithm
pre-announced maximum need
safe states
Require Conditions for deadlock
exclusive use
hold and wait
circular wait
no preemption