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Theoretical practice 3


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Theoretical practice 3

  1. 1. Theoretical Practice 3 Carlos Andrés Galindo García 1416106 Erick Esquivel Treviño 1446516 Esteban Sifuentes Samaniego 1395440
  2. 2. Message Passing <ul><li>The most popular form of interprocess communication involves message passing . Processes communicate with each other by exchanging messages. A process may send information to a port , from which another process may receive information. The sending and receiving processes can be on the same or different computers connected via a communication medium. </li></ul>
  3. 3. Reliable vs Unreliable Messaging <ul><li>Reliable </li></ul><ul><li>Messages are always delivered unless the recipient does not exist. On failure, the sender is notified.   </li></ul><ul><li>  </li></ul><ul><li>Unreliable  </li></ul><ul><li>Messages may/may not be delivered to the recipient.   If a message is delivered, its contents may be corrupted, out of order, or duplicated. </li></ul>
  4. 4. Synchronous vs Asynchronous <ul><li>Synchronous </li></ul><ul><li>  </li></ul><ul><li>Process A delivers the message directly to process B. If process B is not ready to receive at the moment of sending, Process A is suspended and queued upon Process B's 'sending' queue, until Process B is receiving. </li></ul><ul><li>Asynchronous </li></ul><ul><li>  </li></ul><ul><li>Process A sends the message to Process B. The message is copied to a dedicated region in kernel space and attached to Process B's message queue. </li></ul>
  5. 5. Pseudo-Code <ul><li>Synchronization             Addressing                Format </li></ul><ul><li>   Send                             Direct                           Content </li></ul><ul><li>      Blocking                         Send                          Lenght </li></ul><ul><li>      Nonblocking                    receive                      fixed </li></ul><ul><li>   Receive                               explicit                         variable </li></ul><ul><li>       Blocking                           implicit </li></ul><ul><li>      Nonblocking                  Indirect                Queuing Discipline </li></ul><ul><li>      Test for arrival                   Static                        FIFO </li></ul><ul><li>                                              Dynamic                    Priority </li></ul><ul><li>                                              ownership </li></ul><ul><li>                                   </li></ul><ul><li>                                  </li></ul><ul><li>        </li></ul><ul><li>            </li></ul><ul><li>            </li></ul><ul><li>   </li></ul><ul><li>        </li></ul><ul><li>        </li></ul><ul><li>        </li></ul>
  6. 6. Malware Also called badware, malicious code, malware or malicious software is a type of software that aims to infiltrate or damage a computer without the owner's consent
  7. 7. 2 examples of malware <ul><li>rootkits is a set of tools frequently used by computer hackers or crackers illegally gain access to a computer system. For example, if the system is a back door to carry out espionage, the rootkit will hide open portsthat reveal the communication, or if there is a system to send spam, hide the mail system activity </li></ul><ul><li>Hijacker They are in charge of &quot;kidnapping&quot; the functions of our system by changing the home page and search and / or other browser settings. These can be installed on the system without our consentwhen you visit certain web sites using ActiveX controls or to be included by a Trojan </li></ul>
  8. 8. more information about malware <ul><li> </li></ul>
  9. 9. why linux viruses doesn't exist <ul><li>In GNU / Linux, processes, create a code called Daemons (Demons). That is, if  you had FTP server, you would have a daemon listening on port 21 and when you get a connection,the devil would create the process that would manage and continue listening for more connections. The only user who has access to the demons, is SU (super user (super user (root))). Only root has permission to drive the demons. If a virus enters your system as a normal user would do so could not attack the daemon. </li></ul>
  10. 10. cryptology function <ul><li>The easiest way is by adding the character's ASCII value, another value taken from a key word such as bat. The program administrator can change the keyword but must reencriptarall who are saved. char pass[10], cryp[10], clave[10] = {'m', 'u', r', c', i', e', l', a', g', o' }; printf(&quot;Ingrese su password 10 caracteres maximo&quot;) gets(pass); for(i=0; i<10; i++) { cryp[i]=char(int(pass[i]) + int(clave[i]) ); } Then for comparison, the code encrypted by subtracting the value corresponding to the word and compare each of the characters entered, if there is a coincidence in, makes abreak and not allowed to continue. It can be done character by character or use of the library string.h functions to compare strings. </li></ul>
  11. 11. ANDROID SECURITY <ul><li>- PRIVILEGE-SEPARATED (each apliccation has its ID) </li></ul><ul><li>- RESTRICTED PERMISSIONS </li></ul><ul><li>- SANDBOX (Isolated Applications) </li></ul><ul><li>        Any app can run sandbox. </li></ul>
  12. 12. FILE ACCES <ul><li>- Each app special ID remains constant  </li></ul><ul><li>during package's life. </li></ul><ul><li>- Using permissions (manifest)  </li></ul>
  13. 13. ANDROID SOURCE CODE <ul><li>  </li></ul>