Snooping TCP

Snooping TCP

• The access point snoops into the traffic and buffers packets for fast re-transmission.
• Transparent extension of TCP within the foreign agent
• Changes of TCP only within the foreign agent
• Buffering of packets sent to the mobile host
• Lost packets on the wireless link (both directions!) will be retransmitted immediately by the mobile host or foreign agent, respectively (so called “local” retransmission)
• 
  

  

  
  The foreign agent therefore “snoops” the packet flow and recognizes acknowledgements in both directions, it also filters ACKs
• Data transfer to the mobile host
• FA buffers data until it receives ACK of the MH, FA detects packet loss via duplicated ACKs or time-out
• Fast retransmission possible, transparent for the fixed network
• Data transfer from the mobile host
• FA detects packet loss on the wireless link via sequence numbers, FA answers directly with a NACK to the MH
• MH can now retransmit data with only a very short delay

Advantages

• End-to-end semantics is preserved.
• Handover is easy. I-TCP requires a careful handover of the system state. Here it falls back to the standard solution if no enhancements.

Problems

• Snooping TCP does not isolate the wireless link as good as I-TCP
• Snooping might be useless depending on encryption schemes
• Data is transmitted twice in case of a paket loss. Once from the FA to the MH and the second time when the ACK finally reaches the CN.
   

Raja Bahadur Venkat Rama Reddy was born on August 22, 1869, in a middle class family at Rayanpet in Wanaparthy. He lost his parents early in his childhood and was brought up by his uncle, William Wahab, who had a great influence on him. He had great passion for education which made him pursue further studies, in spite of opposition from his relatives.

At the age of 18, Venkat Rama Reddy entered the police service of the erstwhile Hyderabad State and rose to the position of Police Commissioner of Hyderabad City, the first Hindu to do so. The Nizam of Hyderabad honored Sri Venkat Rama Reddy with the title of “Raja Bahadur” in recognition of his services to the state.

King George of England conferred the title of “Order of British Empire’ for solving the Indian Labour problem. A statue has been installed in his memory in the city which is a unique feature for a police officer.

A pioneer in the field of education, he took several measures to spread literacy among the people of the Telangana region and to promote Telugu as the medium of instruction. The education of backward area of Telangana Girls, in particular, received powerful impetus from him. It is this pioneering spirit of his, which made him take the first step in establishing a college for women in the early days of 1949. The college is named after him.

It was the Raja Bahadur, who as the president of the managing committee of the Girl’s High School secured a centrally located land for this college building. This first step proved to be giant leap in the field of women’s education for generations to come. The Raja Bahadur Venkat Rama Reddy women’s college stand today as a proud testimony of his foresight and interest in the upliftment and education of women.

The other educational institution established by him or with his help and co-operation includes Madapati Hanumantha Rao Girls High School in the heart of the city to facilitate students from the districts to come Hyderabad to pursue education.

CN LAB

Computer Networks

1. Character Stuffing
2. Bit Stuffing
3. Cyclic Redundancy Check
4. Dijkstra's Algorithms 
5. Distance Vector Routing Algorithm
6. RSA Algorithm

Operating Systems

Operating Systems

CPU Scheduling Algorithms

1. First Come First Serve (FCFS)
2. Shortest Job First (SJF)  [No pre-emption, with arrival times] Shortest Job First (SJF) [Pre-emptive, with arrival times]
3. Round Robin
4. Priority

Page Replacement Algorithms

1. First In First Out (FIFO)
2. Least Recently Used (LRU)
3. Optimal

Page Replacement Algorithm

FIFO Page Replacement Algorithm

 //FIFO PAGE REPLACEMENT ALGORITHM  
 #include <stdio.h>  
 #include <conio.h>  
 int main()  
 {  
   int n, rss, fa[20], rsa[50]; //n-No_of_Frames  
   //rss->Reference_String_Size::fa->Frame_Array  
   //rsa->Reference_String_Array::ta->Temporary_Array  
   int i,j,k,pfc=0,npf, cp=0;  
   //cp->Current_Position :: ff->Frames_Filled ::pfc->Page_Fault_Count  
   //npf:NO_Page_Faults [0-False, 1-True]  
   printf("Enter number of frames: ");  
   scanf("%d", &n);  
   printf("Enter number of pages in reference string: ");  
   scanf("%d", &rss);  
   printf("Enter Reference string:\n");  
   for(i=0; i<rss; i++)  
     scanf("%d",&rsa[i]);  
   for(i=0;i<n;i++)  
     fa[i]=-1;  
   printf("\nCURRENT_PAGE\t\tPAGES_IN_FRAME\t\tPAGE_FAULT_OCCURED?\n");  
   for(i=0; i<rss; i++)  
   {  
     printf("\n\t%d\t\t",rsa[i]);  
     npf=0;  
     for(j=0;j<n;j++)  //Checking for the page in FRAME ARRAY  
     {  
       if(fa[j]==rsa[i])  
       {  
         npf = 1;  
         printf("\t\t\t\tNO");  
         break;  
       }  
     }  
     if(npf==0)   // if page fault occurs  
     {  
       pfc++;  
       fa[cp] = rsa[i];  
       cp=(cp+1)%n;  
       for(j=0;j<n;j++)  
         printf("%d\t",fa[j]);  
       printf("\tYES");  
     }  
   }  
   printf("\nTotal no of pagefaults: %d",pfc);  
   return 0;  
 }  

LRU Page Replacement Algorithm





 //LRU PAGE REPLACEMENT ALGORITHM  
 #include <stdio.h>  
 #include <conio.h>  
 int main()  
 {  
   int n, rss, fa[20], rsa[50], ta[20]; //n-No_of_Frames  
   //rss->Reference_String_Size::fa->Frame_Array  
   //rsa->Reference_String_Array::ta->Temporary_Array  
   int i,j,k,pfc=0,npf, cp;  
   //cp->Current_Position ::pfc->Page_Fault_Count  
   //npf:NO_Page_Faults [0-False, 1-True]  
   printf("Enter number of frames: ");  
   scanf("%d", &n);  
   printf("Enter number of pages in reference string: ");  
   scanf("%d", &rss);  
   printf("Enter Reference string:\n");  
   for(i=0; i<rss; i++)  
     scanf("%d",&rsa[i]);  
   for(i=0;i<n;i++)  
     fa[i]=-1;  
   for(i=0;i<n;i++)  
     ta[i]=n-(i+1);  
   printf("\nCURRENT_PAGE\t\tPAGES_IN_FRAME\t\tPAGE_FAULT_OCCURED?\n");  
   for(i=0; i<rss; i++)  
   {  
     printf("\n\t%d\t\t",rsa[i]);  
     npf=0;  
     for(j=0;j<n;j++)  //Checking for the page in FRAME ARRAY  
     {  
       if(fa[j]==rsa[i])  
       {  
         npf = 1;  
         for(k=0;k<n;k++)  
           ta[k]++;  
         ta[j]=0;  
         printf("\t\t\t\tNO");  
         break;  
       }  
     }  
     if(npf==0)   // if page fault occurs  
     {  
       pfc++;  
       cp=0;  
       for(j=1;j<n;j++)  
         if(ta[cp]<ta[j])  
           cp=j; //cp->current position  
       fa[cp] = rsa[i];  
       for(k=0;k<n;k++)  
         ta[k]++;  
       ta[cp]=0;  
       for(j=0;j<n;j++)  
         printf("%d\t",fa[j]);  
       printf("\tYES");  
     }  
   }  
   printf("\nTotal no of pagefaults: %d",pfc);  
   return 0;  
 }  

Notes/Study Materials

Computer Forensics Notes/ Study Material

BTech IV I Sem (Computer Forensics) Updated
Theory	Practical
1.       1.   Unit I Part I         Download 2.       Unit I Part II       Download 3.       Unit I Part III     Download 4.       Unit II Part I       Download 5.       Unit II Part II     Download 6.       Unit II Part III   Download

New Android Malware infects 10 million Android Devices 

More than 10m devices running Google’s Android OS have been infected with HummingBad – a new piece of malware that is able to take over a smartphone or tablet, steal and sell on user data, including banking information and other data for identify theft. It is also able to download unauthorized apps and tap on advertising.

Security firms have been tracking the malware for the past few months. According to their statistics, after a spike in infections in May, HummingBad has now passed the 10 million mark. Security experts explain that it can infect an Android device if the user browses the infected website, in so-called “drive-by-download” attacks. After this, the malware tries to gain access to the underlying Android system by using “root access” to take full control. If it fails, it attempts to trick the user into giving almost full control via a fake update alert.

Once HummingBad has control of the Android smartphone or tablet, it can force it to download apps and tap on adverts in order to generate fraudulent advertising revenue without the device owner’s knowledge. Besides, the hackers could sell access to the device or the user’s data. Infected devices have been detected all over the world with 1.6m devices in China, 1.35m in India, 288,000 in the US and 100,000 in the UK and Australia. Google admits it has been aware of that malware and is constantly improving Android, actively blocking installations of infected apps.

Nowadays, smartphones are increasingly popular, so malware targeting both Android and iOS has increased in volume and effectiveness. In response, the platform developers made further moves to protect devices from such malware. However, in this case Apple has had more success in getting users to upgrade to the latest and most secure versions of its operating systems thanks to its control of both hardware and software. As for Android updates, it can take months if not years, because Google does not directly control most of the devices.

Google has recently separated security patches from the rest of the operating system, and now security updates are pushed out on a monthly basis for its own mobile devices. At the same time, other Android manufacturers like Samsung and LG promised to do the same. However, many other manufacturers are slow to release updates to user phones, which leaves users exposed.

If your device is infected with HummingBad, a factory reset might be the only recourse. Moreover, even then it could remain.

Think of your account

Oculus CEO’s Twitter Hacked

witter account of Brendan Iribe, the CEO of Facebook’s virtual reality headset maker, Oculus, was hacked a few days ago, which made him the latest in a long line of important figures to have had their social media accounts breached.

Iribe’s account was taken over several days ago, with a tweet being sent out to his 16,000 followers announcing that Oculus is very excited to announce “its CEO – @Lid“. After this, the hacker @Lid went on to tweet at users and chastise Iribe for using the same pass for 4 years. Iribe’s Twitter account was reclaimed within hours, after the hacker tweeted that he could give it back in exchange for a free oculus rift “so i watch porn the cool way”. It is unknown if Iribe gave in to this demand.

In the meantime, security experts point out that it wasn’t as bad as it could have been for Iribe – in fact, it was more embarrassing than offensive. Anyway, the recent breach once again demonstrated the importance of account security for various online services. Recent account takeovers also included Mark Zuckerberg, Katy Perry, Channing Tatum, Twitter’s former head and Google’s CEO. Security experts continue to warn against trusting interconnected services and weak security, including using an old password.

Forensics

Businessman Sued Apple for $10bn over Stealing a Smartphone Idea
A $10bn lawsuit was filed against the iPhone maker, where Thomas Ross claimed that Apple’s mobile devices infringe his 1992 invention of an Electronic Reading Device. Ross admits that he knows he is fighting a goliath, but believes he has a strong case.

Thomas Ross claims that he worked on the invention for more than a year, drawing on his experience as a software consultant. His efforts resulted in 3 hand-sketched technical drawings of the Electronic Reading Device and filing a patent in 1992.

The invention was conceived as a reading and writing device, with a back-lit screen, able to store media on the device and on remote servers. Ross, who now works as a manager at a law firm, filed a patent 4 years before the Palm Pilot launched and 15 years before the first iPhone. The Electronic Reading Device was conceived to allow one to read stories, view images and watch video on a flat touchscreen, having communication functions like a phone and a modem, and would come with rounded edges in various sizes.

Aside from the 3 hand-scribbled images of the Electronic Reading Device, the inventor also created a flowchart illustrating how media could be requested and downloaded from a remote server along with a description of the purpose, look and feel of the device. However, that invention has never been taken further than the design stage due to the lack of funds. Back in 1992, the inventor failed to pay the required fees and had his patent application declared abandoned 3 years later by the US Patent and Trademark Office. Instead of using patent law, he now sues Apple with copyright law.

A year ago, Ross’s lawyer sent a cease and desist letter to Apple, requesting them to stop distributing the infringing products. Apple responded that the claims “have no merit” and pointed out that Ross was not able to show any evidence that Apple had accessed the patent applications. However, this response didn’t deter Ross, who filed the lawsuit with the US district court, seeking $10bn in damages and demanding Apple to forfeit the patents derived from his designs.

Industry experts call it just a nuisance case filed by an individual hoping to make some money out of it, who doesn’t even have a US patent and just pulled a $10bn number out of nowhere.