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Exploring the Layers of Computer Networks

Discover the OSI model layers and their functions in computer networking. Learn about network devices, protocols, and security. Join the study to become a skilled network administrator.

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Exploring the Layers of Computer Networks

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  1. Computer Network Sritrusta Sukaridhoto

  2. Why Computer Network ??? • Stand alone Computer …. FOR WHAT ???

  3. Something interesting from Computer Network ??? • Easiness • No distance • Mobility • Efficient

  4. Advantages Good salary Control other peoples Faster than others Relax Disadvantages ERROR, then people want to kill YOU !!! Network Administrator,…

  5. Study… • Basic network theory • OSI Layer • Network devices • Routing • Network security • Programming

  6. Study… • Network Skill • Operating system • Server – Client • Router, Switch, Cabling, etc (network devices) • Hacking not Cracking • Certificate • Experience • Time can answer ???

  7. Open System Interconnection (OSI) • A model defines the stages or tasks of a protocol as it prepares to send data • Open meaning standards available to all. • The model is devided into seven distinct layers • Each subsequent layer should perform a well-defined function and the layer boundaries are designed to minimize the information flow across the interfaces

  8. OSI Model Layers • Application Layer • Provides a user interface (examples: HTTP, SMTP) • Includes file, print, database, app. Services • Presentation Layer • Presents the data (example: JPEG) • Includes encryption, compression and translation services • Session Layer • Keeps different applications data separate

  9. OSI Model Layers • Transport Layer • Provides reliable delivery • Performs error detection • Includes end to end connection • Network Layer • Provides logical addressing • Routing layer

  10. OSI Model Layers • Data Link Layer • Combines packets into bytes then into frames • Performs error detection (not correction) • Provides Media access addressing (point-to-point) • Media Access Control and Data Link Control • Physical Layer • Moves bits between devices

  11. Keys Layers of the OSI Model

  12. OSI Model and Protocols

  13. Wired Wireless Network Devices

  14. Router, Switch, Hub, Modem, …

  15. TCP/IP

  16. TCP/IP

  17. Operating Systems

  18. Network Security • Firewall

  19. Hacking NOT cracking

  20. /* ** server.c -- a stream socket server demo */ #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <netinet/in.h> #include <arpa/inet.h> #include <sys/wait.h> #include <signal.h> #define MYPORT 3490 // the port users will be connecting to #define BACKLOG 10 // how many pending connections queue will hold void sigchld_handler(int s) { while(wait(NULL) > 0); } int main(void) { int sockfd, new_fd; // listen on sock_fd, new connection on new_fd struct sockaddr_in my_addr; // my address information struct sockaddr_in their_addr; // connector's address information int sin_size; struct sigaction sa; int yes=1; if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) { perror("socket"); exit(1); } if (setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(int)) == -1) { perror("setsockopt"); exit(1); } my_addr.sin_family = AF_INET; // host byte order my_addr.sin_port = htons(MYPORT); // short, network byte order my_addr.sin_addr.s_addr = INADDR_ANY; // automatically fill with my IP memset(&(my_addr.sin_zero), '\0', 8); // zero the rest of the struct if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) == -1) { perror("bind"); exit(1); } if (listen(sockfd, BACKLOG) == -1) { perror("listen"); exit(1); } sa.sa_handler = sigchld_handler; // reap all dead processes sigemptyset(&sa.sa_mask); sa.sa_flags = SA_RESTART; if (sigaction(SIGCHLD, &sa, NULL) == -1) { perror("sigaction"); exit(1); } while(1) { // main accept() loop sin_size = sizeof(struct sockaddr_in); if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size)) == -1) { perror("accept"); continue; } printf("server: got connection from %s\n", inet_ntoa(their_addr.sin_addr)); if (!fork()) { // this is the child process close(sockfd); // child doesn't need the listener if (send(new_fd, "Hello, world!\n", 14, 0) == -1) perror("send"); close(new_fd); exit(0); } close(new_fd); // parent doesn't need this } return 0; } Programming

  21. Server - Client

  22. Certificate

  23. EEPIS Computer Network • Lab Jaringan Komputer • Ka. Lab: Sritrusta Sukaridhoto • Gedung D4 lt. 3 • UPT Jaringan Komputer • Ka. UPT: Nonot H • Network Admin: Sukaridhoto, Amang • Webmaster: Udinharun • Gedung IT lt. 2

  24. Thank You…

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