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aasthayadavaasthayadav
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VPN
C Program implementation
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4 files changed

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‎.gitattributes

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# Auto detect text files and perform LF normalization
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* text=auto

‎README.md

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# VPN

‎vpnclient.c

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#include <fcntl.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <arpa/inet.h>
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#include <linux/if.h>
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#include <linux/if_tun.h>
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#include <sys/ioctl.h>
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#define BUFF_SIZE 2000
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#define PORT_NUMBER 55555
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#define SERVER_IP "10.0.2.25"
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struct sockaddr_in peerAddr;
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int createTunDevice() {
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int tunfd;
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struct ifreq ifr;
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memset(&ifr, 0, sizeof(ifr));
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ifr.ifr_flags = IFF_TUN | IFF_NO_PI;
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tunfd = open("/dev/net/tun", O_RDWR);
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ioctl(tunfd, TUNSETIFF, &ifr);
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return tunfd;
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}
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/*int connectToUDPServer(){
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int sockfd;
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char *hello="Hello";
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memset(&peerAddr, 0, sizeof(peerAddr));
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peerAddr.sin_family = AF_INET;
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peerAddr.sin_port = htons(PORT_NUMBER);
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peerAddr.sin_addr.s_addr = inet_addr(SERVER_IP);
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sockfd = socket(AF_INET, SOCK_DGRAM, 0);
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// Send a hello message to "connect" with the VPN server
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sendto(sockfd, hello, strlen(hello), 0,
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(struct sockaddr *) &peerAddr, sizeof(peerAddr));
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return sockfd;
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}
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*/
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int connectToTCPServer(){
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int sockfd;
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char *hello="Hello";
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memset(&peerAddr, 0, sizeof(peerAddr));
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peerAddr.sin_family = AF_INET;
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peerAddr.sin_port = htons(443);
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peerAddr.sin_addr.s_addr = inet_addr(SERVER_IP);
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sockfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
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// Send a hello message to "connect" with the VPN server
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sendto(sockfd, hello, strlen(hello), 0,
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(struct sockaddr *) &peerAddr, sizeof(peerAddr));
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return sockfd;
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}
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void tunSelected(int tunfd, int sockfd){
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int len;
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char buff[BUFF_SIZE];
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printf("Got a packet from TUN\n");
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bzero(buff, BUFF_SIZE);
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len = read(tunfd, buff, BUFF_SIZE);
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sendto(sockfd, buff, len, 0, (struct sockaddr *) &peerAddr,
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sizeof(peerAddr));
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}
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void socketSelected (int tunfd, int sockfd){
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int len;
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char buff[BUFF_SIZE];
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printf("Got a packet from the tunnel\n");
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bzero(buff, BUFF_SIZE);
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len = recvfrom(sockfd, buff, BUFF_SIZE, 0, NULL, NULL);
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write(tunfd, buff, len);
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}
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int main (int argc, char * argv[]) {
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int tunfd, sockfd;
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tunfd = createTunDevice();
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sockfd = connectToUDPServer();
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// Enter the main loop
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while (1) {
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fd_set readFDSet;
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FD_ZERO(&readFDSet);
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FD_SET(sockfd, &readFDSet);
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FD_SET(tunfd, &readFDSet);
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select(FD_SETSIZE, &readFDSet, NULL, NULL, NULL);
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if (FD_ISSET(tunfd, &readFDSet)) tunSelected(tunfd, sockfd);
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if (FD_ISSET(sockfd, &readFDSet)) socketSelected(tunfd, sockfd);
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}
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}
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‎vpnserver.c

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#include <fcntl.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <arpa/inet.h>
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#include <linux/if.h>
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#include <linux/if_tun.h>
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#include <sys/ioctl.h>
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#define PORT_NUMBER 55555
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#define BUFF_SIZE 2000
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struct sockaddr_in peerAddr;
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int createTunDevice() {
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int tunfd;
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struct ifreq ifr;
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memset(&ifr, 0, sizeof(ifr));
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ifr.ifr_flags = IFF_TUN | IFF_NO_PI;
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tunfd = open("/dev/net/tun", O_RDWR);
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ioctl(tunfd, TUNSETIFF, &ifr);
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return tunfd;
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}
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int initUDPServer() {
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int sockfd;
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struct sockaddr_in server;
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char buff[100];
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memset(&server, 0, sizeof(server));
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server.sin_family = AF_INET;
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server.sin_addr.s_addr = htonl(INADDR_ANY);
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server.sin_port = htons(PORT_NUMBER);
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sockfd = socket(AF_INET, SOCK_DGRAM, 0);
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bind(sockfd, (struct sockaddr*) &server, sizeof(server));
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// Wait for the VPN client to "connect".
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bzero(buff, 100);
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int peerAddrLen = sizeof(struct sockaddr_in);
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int len = recvfrom(sockfd, buff, 100, 0,
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(struct sockaddr *) &peerAddr, &peerAddrLen);
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printf("Connected with the client: %s\n", buff);
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return sockfd;
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}
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void tunSelected(int tunfd, int sockfd){
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int len;
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char buff[BUFF_SIZE];
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printf("Got a packet from TUN\n");
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bzero(buff, BUFF_SIZE);
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len = read(tunfd, buff, BUFF_SIZE);
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sendto(sockfd, buff, len, 0, (struct sockaddr *) &peerAddr,
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sizeof(peerAddr));
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}
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void socketSelected (int tunfd, int sockfd){
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int len;
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char buff[BUFF_SIZE];
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printf("Got a packet from the tunnel\n");
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bzero(buff, BUFF_SIZE);
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len = recvfrom(sockfd, buff, BUFF_SIZE, 0, NULL, NULL);
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write(tunfd, buff, len);
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}
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int main (int argc, char * argv[]) {
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int tunfd, sockfd;
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tunfd = createTunDevice();
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sockfd = initUDPServer();
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// Enter the main loop
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while (1) {
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fd_set readFDSet;
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FD_ZERO(&readFDSet);
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FD_SET(sockfd, &readFDSet);
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FD_SET(tunfd, &readFDSet);
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select(FD_SETSIZE, &readFDSet, NULL, NULL, NULL);
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if (FD_ISSET(tunfd, &readFDSet)) tunSelected(tunfd, sockfd);
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if (FD_ISSET(sockfd, &readFDSet)) socketSelected(tunfd, sockfd);
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}
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}
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