Optional Lab 2 - Bypassing Firewall using VPN done

Adarsh275 · Dec 20, 2022 · 5e29280 · 5e29280
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diff --git a/Optional Lab 2 - Bypassing Firewall using VPN/Code/vpnclient.c b/Optional Lab 2 - Bypassing Firewall using VPN/Code/vpnclient.c
@@ -0,0 +1,90 @@
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <linux/if.h>
+#include <linux/if_tun.h>
+#include <sys/ioctl.h>
+
+#define BUFF_SIZE 2000
+#define PORT_NUMBER 55555
+#define SERVER_IP "127.0.0.1" 
+struct sockaddr_in peerAddr;
+
+int createTunDevice() {
+   int tunfd;
+   struct ifreq ifr;
+   memset(&ifr, 0, sizeof(ifr));
+
+   ifr.ifr_flags = IFF_TUN | IFF_NO_PI;  
+
+   tunfd = open("/dev/net/tun", O_RDWR);
+   ioctl(tunfd, TUNSETIFF, &ifr);       
+
+   return tunfd;
+}
+
+int connectToUDPServer(){
+    int sockfd;
+    char *hello="Hello";
+
+    memset(&peerAddr, 0, sizeof(peerAddr));
+    peerAddr.sin_family = AF_INET;
+    peerAddr.sin_port = htons(PORT_NUMBER);
+    peerAddr.sin_addr.s_addr = inet_addr(SERVER_IP);
+
+    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+
+    // Send a hello message to "connect" with the VPN server
+    sendto(sockfd, hello, strlen(hello), 0,
+                (struct sockaddr *) &peerAddr, sizeof(peerAddr));
+
+    return sockfd;
+}
+
+
+
+void tunSelected(int tunfd, int sockfd){
+    int  len;
+    char buff[BUFF_SIZE];
+
+    printf("Got a packet from TUN\n");
+
+    bzero(buff, BUFF_SIZE);
+    len = read(tunfd, buff, BUFF_SIZE);
+    sendto(sockfd, buff, len, 0, (struct sockaddr *) &peerAddr,
+                    sizeof(peerAddr));
+}
+
+void socketSelected (int tunfd, int sockfd){
+    int  len;
+    char buff[BUFF_SIZE];
+
+    printf("Got a packet from the tunnel\n");
+
+    bzero(buff, BUFF_SIZE);
+    len = recvfrom(sockfd, buff, BUFF_SIZE, 0, NULL, NULL);
+    write(tunfd, buff, len);
+
+}
+int main (int argc, char * argv[]) {
+   int tunfd, sockfd;
+
+   tunfd  = createTunDevice();
+   sockfd = connectToUDPServer();
+
+   // Enter the main loop
+   while (1) {
+     fd_set readFDSet;
+
+     FD_ZERO(&readFDSet);
+     FD_SET(sockfd, &readFDSet);
+     FD_SET(tunfd, &readFDSet);
+     select(FD_SETSIZE, &readFDSet, NULL, NULL, NULL);
+
+     if (FD_ISSET(tunfd,  &readFDSet)) tunSelected(tunfd, sockfd);
+     if (FD_ISSET(sockfd, &readFDSet)) socketSelected(tunfd, sockfd);
+  }
+}
+
diff --git a/Optional Lab 2 - Bypassing Firewall using VPN/Code/vpnserver.c b/Optional Lab 2 - Bypassing Firewall using VPN/Code/vpnserver.c
@@ -0,0 +1,93 @@
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <arpa/inet.h>
+#include <linux/if.h>
+#include <linux/if_tun.h>
+#include <sys/ioctl.h>
+
+#define PORT_NUMBER 55555
+#define BUFF_SIZE 2000
+
+struct sockaddr_in peerAddr;
+
+int createTunDevice() {
+   int tunfd;
+   struct ifreq ifr;
+   memset(&ifr, 0, sizeof(ifr));
+
+   ifr.ifr_flags = IFF_TUN | IFF_NO_PI;  
+
+   tunfd = open("/dev/net/tun", O_RDWR);
+   ioctl(tunfd, TUNSETIFF, &ifr);       
+
+   return tunfd;
+}
+
+int initUDPServer() {
+    int sockfd;
+    struct sockaddr_in server;
+    char buff[100];
+
+    memset(&server, 0, sizeof(server));
+    server.sin_family = AF_INET;                 
+    server.sin_addr.s_addr = htonl(INADDR_ANY);
+    server.sin_port = htons(PORT_NUMBER);        
+
+    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+    bind(sockfd, (struct sockaddr*) &server, sizeof(server)); 
+
+    // Wait for the VPN client to "connect".
+    bzero(buff, 100);
+    int peerAddrLen = sizeof(struct sockaddr_in);
+    int len = recvfrom(sockfd, buff, 100, 0,                  
+                (struct sockaddr *) &peerAddr, &peerAddrLen);
+
+    printf("Connected with the client: %s\n", buff);
+    return sockfd;
+}
+
+void tunSelected(int tunfd, int sockfd){
+    int  len;
+    char buff[BUFF_SIZE];
+
+    printf("Got a packet from TUN\n");
+
+    bzero(buff, BUFF_SIZE);
+    len = read(tunfd, buff, BUFF_SIZE);
+    sendto(sockfd, buff, len, 0, (struct sockaddr *) &peerAddr,
+                    sizeof(peerAddr));
+}
+
+void socketSelected (int tunfd, int sockfd){
+    int  len;
+    char buff[BUFF_SIZE];
+
+    printf("Got a packet from the tunnel\n");
+
+    bzero(buff, BUFF_SIZE);
+    len = recvfrom(sockfd, buff, BUFF_SIZE, 0, NULL, NULL);
+    write(tunfd, buff, len);
+
+}
+int main (int argc, char * argv[]) {
+   int tunfd, sockfd;
+
+   tunfd  = createTunDevice();
+   sockfd = initUDPServer();
+
+   // Enter the main loop
+   while (1) {
+     fd_set readFDSet;
+
+     FD_ZERO(&readFDSet);
+     FD_SET(sockfd, &readFDSet);
+     FD_SET(tunfd, &readFDSet);
+     select(FD_SETSIZE, &readFDSet, NULL, NULL, NULL);
+
+     if (FD_ISSET(tunfd,  &readFDSet)) tunSelected(tunfd, sockfd);
+     if (FD_ISSET(sockfd, &readFDSet)) socketSelected(tunfd, sockfd);
+  }
+}
+
diff --git a/Optional Lab 2 - Bypassing Firewall using VPN/LAB Setup.txt b/Optional Lab 2 - Bypassing Firewall using VPN/LAB Setup.txt
@@ -0,0 +1,10 @@
+This lab requires SEED LAB 16 as the docker container setup was not working. 
+
+Provided below the link to Seed lab 16 : 
+
+https://seedsecuritylabs.org/lab_env.html
+
+(OR)
+
+google drive link -- https://drive.google.com/file/d/12l8OO3PXHjUsf9vfjkAf7-I6bsixvMUa/view
+
diff --git a/Optional Lab 2 - Bypassing Firewall using VPN/Optinal lab 2 report.pdf b/Optional Lab 2 - Bypassing Firewall using VPN/Optinal lab 2 report.pdf
diff --git a/Optional Lab 2 - Bypassing Firewall using VPN/VPN Bypassing Firewall Lab Manual.pdf b/Optional Lab 2 - Bypassing Firewall using VPN/VPN Bypassing Firewall Lab Manual.pdf
diff --git a/Optional Lab 2 - Bypassing Firewall using VPN/VPN Bypassing Firewall.docx b/Optional Lab 2 - Bypassing Firewall using VPN/VPN Bypassing Firewall.docx