par Weiyan Lin Il y a 9 années
494
Plus de détails
asdf
linux
platform Vmware/virtual Box
centos
kali
penatration test with
metasploit
ubuntu
set up xampp/lamp
fedora
network
platform GNS
OSPF
finished open course from Cay Horstmann (writer of Core Java) from Udacity website
poly morphism
interface
super class
Class
example
vehicle(super class)
truck
car
suv(sub class)
moto
concepts
people send message----class
| |
| |
class method
Method belongs to class
each method i responsible of a single class
collecting ---arraylist
Interface
Poly Morphism
d.draw()
dog.draw() cat.draw() car.draw()
ArrayList
ArrayList<Drawable> draw=new ArrayList <Drawable>;
draw.add(new Dog());
draw.add(new House());
for(drawable d :draw)
{
d.draw();
}
no need : for(dog){dog.draw); for(house){house.draw}
public class Dog implents Drawable
{}
public interface Drawable{ void draw();} //no implement, auto public
static and final
final
final variable
final method
can not overriden
finial class
no change
no subclass
initial and never change
static
not belongs to a specific object belongs to a class
Instance method Pic1,translate() need instance
Static Method : Math.sqrt() no need instance
basic
int-> string xx=""+int_number string-> int Double.parsedouble("3.14")
Scanner in =new Scanner(System.in); int age = in.nextInt
Array,ArrayList
arraylist
add(0,pic)
remove(2)
size()
set(2,obj)
loop
for (int i=0;i<ArrayList.size()/*array.length*/ ;i++)
{}
enhanced loop
for (objectclass obj : obj_arraylist)
{}
declaration
ArrayList
double [] values =new double[10] / double[] values={1,2,3,4,5};
String
charAt
eclipse
OFDM Simulation
teted in AWGN and Rayleigh fading
test in two modulation methods
Designed transmitter, channel and receiver for a give number of active subcarrier, channel bandwidth
GSM Simulation based on numpy and Hata model,Rayleigh fading, plot results with matplotlib in figures
use Matasploit.pyplot lib to plot the results of simulation in figures
Okumura Hata model,shadowing(log-nomal with location variability),fading(Rayleigh fading)
Use Numpy to perform mathmatical operations about the wireless channel's path loss
Analysis wireless Model to improve the GOS from 20% to 2%
Find out the Number of MSs of the system which could provide 20% Grade of service
Calculate the probability of blocked calls and dropped calls
Only focus on downlink transmission, BSs as transmitter and MSs are the receivers
One basic website project based on book "head first"
One basic Android app project based on book "head first"
void qsort(int v[], int left, int right)
{
int i, last;
void swap(int v[],int i, int j)
if (left>=right)
return;
last=left,
swap(v , left, (left+right)/2);
for (i=0;i<right;i++)
{
if (v[i]<v[left])
{ swap( v, last,i);
}
}
swap(v[], left,last)
qsort(v[],left,last)
qsort(v[],last,right)
}
pointers
pointers to pointers
lineptr is itself the name oa an array, it can be treated as a pointer
#include <stdio.h>
#include <string.h>
#define MAXLINES 5000l
char *lineptr[MAXLINES];
int readlines(char *lineptr[], int nlines);
int writelines(char *lineptr[],int nlines);
void qsort(char *lineptr[], int left,int right)
main()
{
int nlines;
if ((nlines=readlines(lineptr, MAXLINES) >=0)
{
qsort(lineptr,0,nlines-1);
writelines(lineptr,nlines);
return 0;
}
else
{
printf("error")
return 1;
}
}
}
readlines
#define MAXLEN 1000
int getline(char *s, int);
/* readlin read input lines*/
int readlines(char *lineptr[]; int maxlines)
{
int len,nlines;
char *p,line[MAXLEN];
nlines=0;
while( (len=getline(line,MAXLEN) > =0)
{
if ( nlines> MAXLINES || (p=alloc(len))== NULL)
{
return -1;
}
else
{
line[len-1]='\0'; /* all \0*/
strcpy(p,line);
lineptr[nlines++]=p;
}
return nlines;
}
getlines
/* input s[], return the length of s*/
int getline(char s[],int lim)
{
int i,v;
for (i=0; (c=getchar())!=EOF&& i<lim-1& c!='"\0";++i)
{
s[i]=c;
}
if (c == "\n")
{
s[i]=c;
++i;
}
s[i]="\0";
return i;
return i
}
writelines
/* writelines */
void writelines(char *lineptr[], int nlines)
{
while ( nlines-- >0)
{
printf(" %s\n",*linesptr++);
}
}
lineptr is an array of MAXLINES elements, each element of which is a pointer to a char. That is , lineptr[i] is a character pointer, and *lineptr[i] is the character it points to , the first character of the i-th saved text line.
char *lineptr[MAXLINES]
character pointers and functions
void strcpy(char *s, char *t)
{
int i;
while( (s[i]=t[i]) != "\0")
{
i++;
}
}
/* version 2*/
void strcpy( char *s, char *t)
{
while ( (*s=*t)!="\0")
{
s++;
t++;
}
}
/* version 3 */
void strcpy(char *s, char *t)
{
while ( (*s++=*t++))
;
}
int strcmp(char *s,char *t)
{
for (;*s==*t;s++,t++)
{
if (*s=="\0")
{ return 0;}
}
return *s-*t;
}
char amessage[]="now is the time"; char *amessage="now is the time";
pointer arithmetic
char ,float,int,long
pointer arithmetic is constent , dealing with floats, p++ would advance to the next float.
size_t of strlen, size_t is the unsigned integer type return by sizeof
point to next free element
allocp
large character array
allocbuf
two routine
afree
static char *allocp=allocbuf;
void afree (char *p) /*free storge pointed to by p */
{
if (p>=allocbuf && p<=allocbuf + ALLOCSIZE)
{
allocp=p;
}
}
int strlen(char *s)
{
char *p=s;
while(p!='\0')
{
p=p+1;
}
return p-s;
}
alloc
#define ALLOCSIZE 10000
static char allocbuf[ALLOCSIZE];
static char *allocp=allocbuf;
char *alloc(int n) /* return pointer to n characters*/
{
if (allocbuf + ALLOCSIZE -allocp-n >=0)
{
allocp=allocp+n;
return allocp-n;
}
else
{
return 0;
}
}
pointers and arrays
int a[10];
int *pa;
pa = &a[0];
x= *pa;
*(pa+1) a[1]
as formal parameters in a function definition: char a[] equivalent to char *a;
when an aray name is passed t a function, what is passed is the location of the initial element. int strlen(char *s) { int n; for (n=0;*s!="\0";s++) { n++; } return n; }
poniters is a variable, array is not
pa=&a[0]; pa=a; equal!
there is a strong relationship between pointers and arrays, strong enough that pointers and arrays should be discussed simultaneously.
poniters and function argument
void swap(*p,*q) { int temp; temp=*p; *p=*q; *q=tmp; }
swap(&a,&b)
pointers and address
int x=1,y=2,z[10];
int *ip; /* ip as a pointer*/
ip = &x; /* ip is now point to x*/
y=*ip; /* y=1 now */
*ip=0; /*x=0 now*/
unary operator & gives the address of an object: p=&c
pointers is a group of cells that can hold an address
Network programming TCP/IP
vim,gcc,gdb
unordered array :insert 1;del Max N,Max N ordered array:insert N;del Max 1;Max 1 goal: insert logN;del Max logN; Max 1
remove the largest or smallest one
applications
find the Largest M items in a stream of N items constraints: not enough memory for N items
time:NlogM space :M
elementary
time :MN space:N
sort
time: NlogN space N
Graph search
Dijikstra's Algorithm
event driven simulation
customers in line
system sort
guarantee faster in practice
nlogn
implement
public class merge
{
private static void merge(Comparable[] a, Comparable[] b, int lo, int hi)
{
for(int i=lo;i<hi;i++)
{
b[i]=a[i];
}
int mid=(lo+hi)/2;
int j=mid;
for(int k=lo;k<hi;k++)
{
if(i>mid) a[k]=b[j++];
else if(j>hi) a[k]=b[i++];
else if(b[i]>b[j]) a[k]=b[j++];
else if(b[i]<b[j]) a[k]=b[i++];
}
}
private static void sort(Comparable[] a, Comparable[] b,int lo,int hi)
{
if(hi<lo) return;
int mid=(lo+hi)/2;
sort(a,b,lo,mid);
sort(a,b,mid+1,hi);
merge(a,b,lo,hi);
}
public static void sort(Comparable[] a)
{
aux=new Comparable[a.length];
sort(a,aux,0,a.length-1);
}
}
stable
shuffling sort
generate r (0,i) and swap (r ,i),i++
n
generate random for each one and use them as their key to sort
nlogn or n^2
shell sort
speciall insertion sort
insertion sort
alway sort a[j]anda[j-1] and swap
selection sort
alway find min the rest and ,input min into sorted part
stack applications
arithmetic expression evaluation
(1+((2+3)*(4*5)))==123+445**+ operator occurs after two values
right parenthesis:ignore left parenthesis:pop operator and two values; then push the result of applying that operator
operator stack
value stack
compiler implements a function
pop return address and local environment
push local environment and return address
back button
undo in a word processor
iterators
public class Stack<Item> implements Iterable<Item>
{
public Iterator<Item> iterator()
{ return new ReverseArrayIterator() }
private Iterator<Item> iterator implements Iterator<Item>
{
private Node current = first;
public boolean hasNext() {return current!=null;}
public Item next()
{
Item item=current.item;
current=current.next;
return item;
}
}
}
}
what is an Iterable
generic
public class stack
public class stack
we also want StackOfURL,stackOfInts,StackOfVans....
Queue implementation
public class LinkedQueueOfString
{
private Node first,last;
private class Node
{
String data;
Node next;
}
public boolean isEmpty();
{
return first==last;
}
public void Enqueue(String newString)
{
Node oldlast=last;
last=new Node();
last.data=newString;
last.next=null;
if (isEmpty()) first=last;
else oldlast.next=last;
}
public String dequeue()
{
String item=first.item;
first=first.next;
if (isEmpty()) last=null;
return item;
}
}
stacks implementaion
//implement stack in linkedlist
public class LinkedStackOfStrings
{
private Node first=null;
private class Node
{
String item;
Node next;
}
public boolean isEmpty()
{
return first==null;
}
public void push(String news)
{
Node oldfirst=first;
first=new Node();
first.item=news;
first.next=oldfirst;
}
public String pop()
{
String pop=first.item;
first=first.next;
return item;
}
}
//implement stack in array
public class LinkedStackOfStrings
{
private int N=0;
private String[] s;
public setsize(int size);
{
s=new String(size);
}
public void push ( String item)
{
if (N==s.length) resize(s.length*2);
S[N]=item;
N=N+1;
}
public String pop()
{
N=N-1;
String re=s[N];
s[N]=null;
if (N<s.length/4) resize(s.length/2);
return re;
}
public boolean isEmpty()
{
return N==0;
}
public void resize(int size)
{
String n=new String(size);
for(int i=0;i<N;i++)
{
n[i]=s[i];
}
s=n;
}
}
Resizing -array
every operation takes constant amrtized time
less wasted space
linked-list
extra time and space to deal with the links
everyopertions take constant time in the worst case
stack lifo;Queue fifo
operations
test if empty
iterate
knowledge
method
mathematical analysis
explain behavior
empirical analysis
make predictions
java usage
char[] array
2N + 24
padding
ech object uses a multiple of 8 bytes
4 bytes
reference
8 bytes
object overhead
16bytes
type
best case
average case
worst case
common notation
Tilde-notation
Big O
running time
exponetial
cubic
quardratic
linearithmic
O(nlogn)
linear
O(n)
logarithmic
O(logn)
constant
O(1)
interview question
drop egg
Egg drop.
Version 0: 1 egg, =T tosses.
-------> from 1 , one floor and the other
Version 1: ~1lgN eggs and ~1lgN tosses.
-------> from N/2 floor--->[0,N/2]or [N/2,0]--->.....
Version 2: ~lgT eggs and ~2lgT tosses.
-------> for 1 floor to drop , and than 2*Floor ------> 1, 2, 4, 8,.....T
times< logT, eggs <lgT
Version 3: 2 eggs and ~2sqrt(N) tosses.
-------> from 0 floor to sqrt(N), then sqrt(N) to 2sqrt(N),finally find a*sqrt(N),(a+a)*sqrt(N)
sqrt(N)
Version 4: 2 eggs and =cTsqrt(v) tosses for some fixed constant c.
-------> from 0 to c then
Search in a bitonic array
import java.util.Arrays;
public class fastthreeSum
{
public static int peak(int []a)
{
int N=a.length;
for(int i=1;i<N;i++)
{
if(a[i-1]<a[i]&&a[i]<a[i+1])
{
return i;
}
}
}
public static int search(int [] a,int x)
{
int N=a.length;
int mid=peak(a);
int []m=new int[mid];
int []n=new int[N-mid];
for(int i=0;i<mid;i++)
{
m[i]=a[i];
}
for(int i=0;i<N-mid;i++)
{
n[i]=a[i+mid];
}
int q=Arrays.binarySearch(m,x);
int p=Arrays.binarySearch(n,x);
return p&q;
}
}
3-SUM in quadratic time.
public class fastthreeSum
{
public static boolean test (int[] a)
{
int N=a.length;
for(int i=0;i<N;i++)
{
if (a[i]==a[i-1])
{
return true;
}
}
return false;
}
public static void printall(int[] a)
{
int N=a.length;
Array.sort(a);
if(test(a)) throw new IllegalArgumentException("array has duplicate");
for (int i=0;i<N;i++)
{
for (int j=i;j<N;j++)
{
int k=Arrays.binarySearch(a, -(a[i]+a[j]));
System.out.println(a[k]+" "+a[i]+" "+a[j]);
}
}
}
}
DFS
BFS
graph class
class Graph:
def __init__(self):
self.vertList = {}
self.numVertices = 0
def addVertex(self,key):
self.numVertices = self.numVertices + 1
newVertex = Vertex(key)
self.vertList[key] = newVertex
return newVertex
def getVertex(self,n):
if n in self.vertList:
return self.vertList[n]
else:
return None
def __contains__(self,n):
return n in self.vertList
def addEdge(self,f,t,cost=0):
if f not in self.vertList:
nv = self.addVertex(f)
if t not in self.vertList:
nv = self.addVertex(t)
self.vertList[f].addNeighbor(self.vertList[t], cost)
def getVertices(self):
return self.vertList.keys()
def __iter__(self):
return iter(self.vertList.values())
__iter__(self)
iter(self.vertList.values())
def getVertices(self)
self.vertList.keys()
addEdge(f,t,cost)
self.vertList[f].addNeighbor(self.verteList[t],cost)
add t
add f
get Vertex(self,n)
return None
if n in self.vertexList: return self.vertexList[n]
add Vertex(self,key)
return newVertex
self.vertList[key]=newVertex
newVertex=Vertex(key)
numVertices++
Init
numVertices
vertList
vertex class
class Vertex:
def __init__(self,key):
self.id = key
self.connectedTo = {}
def addNeighbor(self,nbr,weight=0):
self.connectedTo[nbr] = weight
def __str__(self):
return str(self.id) + ' connectedTo: ' + str([x.id for x in self.connectedTo])
def getConnections(self):
return self.connectedTo.keys()
def getId(self):
return self.id
def getWeight(self,nbr):
return self.connectedTo[nbr]
get weight
return self.getconnected[nbr]
get Id
return self.id
get connections
self.connectedTo.keys()
addNeighbor
self.connectedTo[nbr]=weight
self.connectedTo={}
self.id=key
binary search Tree
binary heap
class BinHeap:
def __init__(self):
self.heapList=[0]
self.currentSize=0
def insert(self,k):
self.heapList.append(k)
self.currentSize=self.currentSize+1
self.percUp(self.currentSize)
def percUp(self,i):
while i//2 > 0:
if self.heapList[i] < self.heapList[i//2]:
tmp=self.heapList[i//2]
self.heapList[i//2]=self.heapList[i]
self.heapList[i]=tmp
i=i//2
def minChild(self,i):
if i*2+1 > self.currentSize:
return i*2
else:
if self.heapList[i*2]<self.heapList[i*2+1]:
return i*2
else:
return i*2+1
def perDown(self,i):
while(i*2) <= self.currentSize:
mc=self.minChild(i)
if self.heapList[i]>self.heapList[mc]:
tmp=self.heapList[i]
self.heapList[i]=self.heapList[mc]
self.heapList[mc]=tmp
i=mc
def delMin(self):
retval=self.heapList[1]
self.heapList[1]=self.heaplist[self.currentSize]
self.currentSize=self.currentSize-1
self.heapList.pop()
self.percDown(1)
return retval
def buildHeap(self,alist):
i=len(alist)//2
self.currentSize=len(alist)
self.heapList=[0]+alist[:]
while (i>0):
self.perDown(i)
i=i-1
currentSize
heapList
delMin
return
perDown(1)
heapList.pop()
currentSize--
self.heapList[1]=self.heapList[currentSize]
retval=self.HeapList[1]
perDown
if heapList[i]>heapList[mc],swap
mc=minChild(i)
while i*2
minChild
getthe min heapList[i] of i between i*2 and i*2+1
percUp
i=i//2 until i=0
heapList[i//2]> heapList[i] swap
i//2
currentSize++
perup(currentSize)
heapappend
Subtopic
binary tree
class BinaryTree:
def __init__(self,rootobj):
self.key=rootobj
self.leftchild=None
self.rightchild=None
def insertleft(self,newNode):
if self.leftchild==None:
self.leftchild=BinaryTree(newNode)
else:
t=BinaryTree(newNode)
t.leftchild=self.leftChild
self.leftChild=t
def insertright(self,newNode):
if self.rightChild==None:
self.right=BinaryTree(newNode)
else:
t=BinaryTree(newNode)
t.rightChild=self.rightChild
self.rightChild=t
def getRightChild(self):
return self.rightChild
def getLeftChild(self):
return self.leftChild
def setRootVal(self,obj):
return self.key=obj
def getRootVal(self):
return self.key
insert rightChild,get rightChild
insert leftChild,get leftChild
setRootVal,getRootVal
_init_(obj)
self.leftChild=None
self.rightChiled=None
self.key=obj
quick sort
def quick(list):
if list=[]
return []
else:
pilot=list[0]
lesser=quick([x for x in list if x<pilot])
greater=quick([x for x in list if x>pilot])
return lesser+pilot+greater
merge sort
def merge(list):
middle=len(list)/2
left=merge(list[:middle])
right=merge(list[middle:])
return mergesort(left,right)
def mergesort(left,right):
i,j=0,0
result=[]
while i<len(left) and j<len(right):
if left[i]<right[j]:
result.append(left[i])
i=i+1
else
result.append(right[j])
j=j+1
result+=left[i:]
result+=right[j:]
return result
List
Queues
class Queue:
def __init__(self):
self.items=[]
def isEmpty(self):
return self.items==[]
def enqueue(self,item):
self.items.insert(0,item)
def size(self):
return len(self.items)
dequeue
pop()
enqueue
insert(0,item)
Stacks
class Stack:
def __init__(self):
self.items=[]
def isEmpty(self):
return self.items==[]
def push(self,item):
self.items.append(item)
def pop(self,item):
self.items.pop()
def size(self):
return len(self.items)
push
append
implementing list
list class
class List:
def __init__(self):
self.head=None
def isEmpty(self):
return self.head==None
def add(self,item):
temp=Node(item)
temp.setNext(self.head)
self.head=temp
def size(self):
current=self.head
count =0
while current != None:
count=count+1
current=current.getNext()
return count
def search(self,item):
current=self.head
found=False
while current != None and not found:
if current.getData() == item:
found=True
else:
current=current.getNext()
return found
def remove(self,item):
current=self.head
previous=None
found=False
while current != None and not found:
if current.getdata == item:
found=True
else:
previous=current
current=current.getNext()
if previous == None:
self.head==current.getNext()
else:
previous.setNext(current.setNext())
def append(self,item):
current=self.head
append=Node(item)
while current.getNext() != None:
current=current.getNext()
current.setNext(append)
def index(self,item):
current=self.head
found=False
count=0
while not found:
if current.getdata == item:
found=True
return count
else:
current=current.getNext()
count=count+1
return False
def insert(self,pos,item):
current=self.head
count=0
previous=None
while count<pos:
previous=current.getNext()
count=count+1
newitem=Node(item)
newitem.setNext(previous.getNext())
previous.setNext(newitem)
def pop(self):
current=self.head
found = False
previous=None
while current.getNext != None:
previous=current
current=current.getNext()
previous.setNext(None)
return current.getData()
def pop(self,pos):
current=self.head
count=0
previous=None
if self.size < pos:
return False
while count < pos :
previous=current
current=current.getNext()
count=count+1
previous.setNext(current.getNext)
pop
insert
size
isEmpty
search
remove
add/append
Node class
class Node:
def __init__(self,initdata):
self.data=initdata
self.next=None
def getData(self):
return self.data
def getNext(self):
return self.next
def setData(self,newdata):
self.data=newdata
def setNext(self,newnext):
self.next=newnext
init
setNext
setData
getNext
getData
sed '/tea/s//milk/g' filename
awk '/good/ {print $3}' filename
grep 'good' filename
makefile
clean
main
handshake
authentication key exchange
slow
suitable
model
esp
AH
testing
Reporting and Quantization of Severity
All vulnerability are assigned severity values to quantify the risk based on CVSS
All vulnerability found are documented in a report
high severity vulnerability report immediately
Test Evaluation and exploitation
if vulnerability cannot practically and safely exploited, it will be reported as-is with information
attempt to do safe and pratical exploitation and do report
Vulnerability Scanning
Metasploit
Burp Suite
Nessus
Nmap
Information Gathering
Initial Scanning
In-scope web site
DNS
syn common port
customer-provided
source code
hostnames
Ip adds
tool
get hash
john
hash functiion
DSS
secure hash algorithm (sha)
to detect changes to message
symmetric
public keand & private key
key distribution
asymmetric
single key
kali sql map
kali platform
Physical
conveys bits stream
Hardware interface
Data Link
Mac
identify computer
LLC
interface between ntetwork and MAC, protocol multiplexing, flow control
packet decode and in code into bits
Network
congestion control
inter-network
addressing
forwarding
logical path
Transport
flow control
end to end recovery
transport
Session
manage connection between applications
Web request
SQL
Presentation
formats and encrypt
synchronize
physical
trammit each frame
Frame-ralay / data link
add frame header
IP
break segments to requirements
TCP
duplicate segments
segment data
Application
encrypt
data
Trouble Shooting
Switch
Route
EIGRP
does not have a complete map
only advertises its best route to its neighbour
neighbour relationship
Triggered updates
BGP
OSPF
Link-State
RIP
Distance vector
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