LCX端口转发源码分析

lcx.exe算是端口转发工具中普及率特别高的吧。当然，最近也出了好些Web端口转发工具，这个待后续再分析一下。我从网上下载了一个lcx的源码片段，结合源码谈谈自己的认识。

      lcx工作原理是使不同端口之间形成一个回路，这样就可以进行端口转发。常用于外网连接内网3389端口。具体使用方法网上一堆。

      这个程序主要采用Socket来实现，有几个比较重要的函数：bind2bind、bind2conn、conn2conn及transmitdata。transmitdata函数是核心，这个函数作用是使得不同端口之间的数据形成一个回路。

      注意源代码中的setsocket函数，其中设置了SO_REUSEADDR。设置SO_REUSEADDR之后，可以应用的一种场景就是同一个端口可以绑定多个socket。查看相关资料可以得知，其实设置SO_REUSEADDR之后，还有其他几种应用场景。我试了一下，你把setsocket函数注释掉，在运行这个端口转发程序时，本地listen的时候设置的两个端口不一样程序还是可以正常运行的。启用setsocket函数之后，本地listen的时候，可以设置两个端口为同一个值，但是这样设置的时候，我在虚拟机中无法远程连接，一直就是尝试连接也不报错。原因不因，未深入分析。

      网上很多的源码其实是有问题的，下面我分享一个稍作修改的源代码，能够在windows xp +vc6.0下编译通过，理论上是可以在windows系列所有32位版本下运行的。对于64位系统，我也修改了一个版本，在windows 7 x64+vs2013编译通过，主要用于64位windows下运行。可执行文件我就不放出来了，自己编译运行差不多就OK了。

      Windows XP +VC6.0下编译通过的源码：

/************************************************************************************** * HTran.cpp - HUC Packet Transmit Tool.** Copyright (C) 2000-2004 HUC All Rights Reserved.** Author : lion* : lion#cnhonker.net* : <a href="http://www.cnhonker.com" target="_blank">http://www.cnhonker.com</a>* :* Notice : Thx to bkbll (bkbll#cnhonker.net)* :* Date : 2003-10-20* :* Complie : cl HTran.cpp* :* Usage : E:\>HTran* : ======================== HUC Packet Transmit Tool V1.00 =======================* : =========== Code by lion & bkbll, Welcome to <a href="http://www.cnhonker.com" target="_blank">http://www.cnhonker.com</a> ==========* :* : [Usage of Packet Transmit:]* : HTran - [-log logfile]* :* : [option:]* : -listen * : -tran * : -slave **************************************************************************************/#include <stdio.h>#include <stdlib.h>#include <winsock2.h>#include <signal.h>#include <errno.h>#include <io.h> #pragma comment(lib, "ws2_32.lib") #define VERSION "1.00"#define TIMEOUT 300#define MAXSIZE 20480#define HOSTLEN 40#define CONNECTNUM 5 // define 2 socket structstruct transocket {    SOCKET fd1;    SOCKET fd2;}; // define function void ver();void usage(char *prog);void transmitdata(LPVOID data);void getctrlc(int j);void closeallfd();void makelog(char *buffer, int length);void proxy(int port);void bind2bind(int port1, int port2);void bind2conn(int port1, char *host, int port2);void conn2conn(char *host1, int port1, char *host2, int port2);int testifisvalue(char *str);int create_socket();int create_server(int sockfd, int port);int client_connect(int sockfd, char* server, int port); // define GLOBAL variable hereextern int errno;FILE *fp;int method=0;//int connectnum=0; //************************************************************************************// // function main 主要是处理用户参数输入的问题////************************************************************************************VOID main(int argc, char* argv[]){    char **p;    char sConnectHost[HOSTLEN], sTransmitHost[HOSTLEN];    int iConnectPort=0, iTransmitPort=0;    char *logfile=NULL;         ver();    memset(sConnectHost, 0, HOSTLEN);    memset(sTransmitHost, 0, HOSTLEN);         p=argv;    while(*p)    {        if(stricmp(*p, "-log") == 0)        {            if(testifisvalue(*(p+1)))            {                logfile = *(++p);            }             else            {                printf("[-] ERROR: Must supply logfile name.\r\n");                return;            }            p++;            continue;        }        p++;    }         if(logfile !=NULL)    {        fp=fopen(logfile,"a");        if(fp == NULL )         {            printf("[-] ERROR: open logfile");            return;        }             makelog("====== Start ======\r\n", 22);    }              // Win Start Winsock.    WSADATA wsadata;    WSAStartup(MAKEWORD(2, 2), &wsadata);         signal(SIGINT, &getctrlc);         if(argc > 2)    {        if(stricmp(argv[1], "-listen") == 0 && argc >= 4)        {            iConnectPort = atoi(argv[2]);            iTransmitPort = atoi(argv[3]);            method = 1;        }        else        if(stricmp(argv[1], "-tran") == 0 && argc >= 5)        {            iConnectPort = atoi(argv[2]);            strncpy(sTransmitHost, argv[3], HOSTLEN);            iTransmitPort = atoi(argv[4]);            method = 2;        }        else        if(stricmp(argv[1], "-slave") == 0 && argc >= 6)        {            strncpy(sConnectHost, argv[2], HOSTLEN);            iConnectPort = atoi(argv[3]);            strncpy(sTransmitHost, argv[4], HOSTLEN);            iTransmitPort = atoi(argv[5]);            method = 3;        }    }         switch(method)    {        case 1:        bind2bind(iConnectPort, iTransmitPort);        break;        case 2:        bind2conn(iConnectPort, sTransmitHost, iTransmitPort);        break;        case 3:        conn2conn(sConnectHost, iConnectPort, sTransmitHost, iTransmitPort);        break;        default:        usage(argv[0]);        break;    }         if(method)    {        closeallfd();    }         WSACleanup();         return;}  //************************************************************************************// // print version message////************************************************************************************VOID ver() {     printf("======================== HUC Packet Transmit Tool V%s =======================\r\n", VERSION);    printf("=========== Code by lion & bkbll, Welcome to http://www.cnhonker.com==========\r\n\n");} //************************************************************************************// // print usage message////************************************************************************************VOID usage(char* prog) {     printf("[Usage of Packet Transmit:]\r\n");    printf(" %s - [-log logfile]\n\n", prog);    printf("[option:]\n");    printf(" -listen \n");    printf(" -tran \n");    printf(" -slave \n\n");    return;} //************************************************************************************// // test if is value ////************************************************************************************int testifisvalue(char *str){    if(str == NULL ) return(0);    if(str[0]=='-') return(0);    return(1);} //************************************************************************************// // LocalHost:ConnectPort transmit to LocalHost:TransmitPort////************************************************************************************void bind2bind(int port1, int port2){    SOCKET fd1,fd2, sockfd1, sockfd2;    struct sockaddr_in client1,client2;    int size1,size2;         HANDLE hThread=NULL;    transocket sock;    DWORD dwThreadID;         if((fd1=create_socket())==0) return;    if((fd2=create_socket())==0) return;         printf("[+] Listening port %d ......\r\n",port1);    fflush(stdout);         if(create_server(fd1, port1)==0)    {        closesocket(fd1);        return;    }         printf("[+] Listen OK!\r\n");    printf("[+] Listening port %d ......\r\n",port2);    fflush(stdout);    if(create_server(fd2, port2)==0)    {        closesocket(fd2);        return;    }         printf("[+] Listen OK!\r\n");    size1=size2=sizeof(struct sockaddr);    while(1)    {        printf("[+] Waiting for Client on port:%d ......\r\n",port1);        if((sockfd1 = accept(fd1,(struct sockaddr *)&client1,&size1))<0)        {            printf("[-] Accept1 error.\r\n");            continue;        }         printf("[+] Accept a Client on port %d from %s ......\r\n", port1, inet_ntoa(client1.sin_addr));    printf("[+] Waiting another Client on port:%d....\r\n", port2);    if((sockfd2 = accept(fd2, (struct sockaddr *)&client2, &size2))<0)    {        printf("[-] Accept2 error.\r\n");        closesocket(sockfd1);        continue;    }         printf("[+] Accept a Client on port %d from %s\r\n",port2, inet_ntoa(client2.sin_addr));    printf("[+] Accept Connect OK!\r\n");         sock.fd1 = sockfd1;    sock.fd2 = sockfd2;         hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)transmitdata, (LPVOID)&sock, 0, &dwThreadID);     if(hThread == NULL)     {        TerminateThread(hThread, 0);        return;    }         Sleep(1000);    printf("[+] CreateThread OK!\r\n\n");    }} //************************************************************************************// // LocalHost:ConnectPort transmit to TransmitHost:TransmitPort////************************************************************************************void bind2conn(int port1, char *host, int port2){    SOCKET sockfd,sockfd1,sockfd2;    struct sockaddr_in remote;    int size;    char buffer[1024];         HANDLE hThread=NULL;    transocket sock;    DWORD dwThreadID;         if (port1 > 65535 || port1 < 1)    {        printf("[-] ConnectPort invalid.\r\n");        return;    }         if (port2 > 65535 || port2 < 1)    {        printf("[-] TransmitPort invalid.\r\n");        return;    }         memset(buffer,0,1024);    if((sockfd=create_socket()) == INVALID_SOCKET) return;         if(create_server(sockfd, port1) == 0)     {        closesocket(sockfd);        return;    }         size=sizeof(struct sockaddr);    while(1)    {        printf("[+] Waiting for Client ......\r\n");         if((sockfd1=accept(sockfd,(struct sockaddr *)&remote,&size))<0)        {        printf("[-] Accept error.\r\n");        continue;    }         printf("[+] Accept a Client from %s:%d ......\r\n",    inet_ntoa(remote.sin_addr), ntohs(remote.sin_port));    if((sockfd2=create_socket())==0)     {        closesocket(sockfd1);        continue;     }    printf("[+] Make a Connection to %s:%d ......\r\n",host,port2);    fflush(stdout);         if(client_connect(sockfd2,host,port2)==0)    {        closesocket(sockfd2);        sprintf(buffer,"[SERVER]connection to %s:%d error\r\n", host, port2);        send(sockfd1,buffer,strlen(buffer),0);        memset(buffer, 0, 1024);        closesocket(sockfd1);        continue;    }         printf("[+] Connect OK!\r\n");         sock.fd1 = sockfd1;    sock.fd2 = sockfd2;         hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)transmitdata, (LPVOID)&sock, 0, &dwThreadID);     if(hThread == NULL)     {        TerminateThread(hThread, 0);        return;    }         Sleep(1000);    printf("[+] CreateThread OK!\r\n\n");    }} //************************************************************************************// // ConnectHost:ConnectPort transmit to TransmitHost:TransmitPort////************************************************************************************void conn2conn(char *host1,int port1,char *host2,int port2){    SOCKET sockfd1,sockfd2;         HANDLE hThread=NULL;    transocket sock;    DWORD dwThreadID;    fd_set fds;    int l;    char buffer[MAXSIZE];         while(1)    {             if((sockfd1=create_socket())==0) return;        if((sockfd2=create_socket())==0) return;                 printf("[+] Make a Connection to %s:%d....\r\n",host1,port1);        fflush(stdout);        if(client_connect(sockfd1,host1,port1)==0)         {            closesocket(sockfd1);            closesocket(sockfd2);            continue;        }                 // fix by bkbll         // if host1:port1 recved data, than connect to host2,port2        l=0;        memset(buffer,0,MAXSIZE);        while(1)        {            FD_ZERO(&fds);            FD_SET(sockfd1, &fds);            if (select(sockfd1+1, &fds, NULL, NULL, NULL) == SOCKET_ERROR)             {                if (errno == WSAEINTR) continue;                break;            }            if (FD_ISSET(sockfd1, &fds))             {                l=recv(sockfd1, buffer, MAXSIZE, 0);                break;            }            Sleep(5);        }                 if(l<=0)         {             printf("[-] There is a error...Create a new connection.\r\n");            continue;        }        while(1)        {            printf("[+] Connect OK!\r\n");            printf("[+] Make a Connection to %s:%d....\r\n", host2,port2);            fflush(stdout);            if(client_connect(sockfd2,host2,port2)==0)             {                closesocket(sockfd1);                closesocket(sockfd2);                continue;            }                         if(send(sockfd2,buffer,l,0)==SOCKET_ERROR)            {                 printf("[-] Send failed.\r\n");                continue;            }                         l=0;            memset(buffer,0,MAXSIZE);            break;        }                 printf("[+] All Connect OK!\r\n");                 sock.fd1 = sockfd1;        sock.fd2 = sockfd2;                     hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)transmitdata, (LPVOID)&sock, 0, &dwThreadID);         if(hThread == NULL)         {            TerminateThread(hThread, 0);            return;        }                 // connectnum++;                 Sleep(1000);        printf("[+] CreateThread OK!\r\n\n");    }} //************************************************************************************// // Socket Transmit to Socket////************************************************************************************void transmitdata(LPVOID data){SOCKET fd1, fd2;transocket *sock;struct timeval timeset;fd_set readfd,writefd;int result,i=0;char read_in1[MAXSIZE],send_out1[MAXSIZE];char read_in2[MAXSIZE],send_out2[MAXSIZE];int read1=0,totalread1=0,send1=0;int read2=0,totalread2=0,send2=0;int sendcount1,sendcount2;int maxfd;struct sockaddr_in client1,client2;int structsize1,structsize2;char host1[20],host2[20];int port1=0,port2=0;char tmpbuf[100]; sock = (transocket *)data;fd1 = sock->fd1;fd2 = sock->fd2; memset(host1,0,20);memset(host2,0,20);memset(tmpbuf,0,100); structsize1=sizeof(struct sockaddr);structsize2=sizeof(struct sockaddr); if(getpeername(fd1,(struct sockaddr *)&client1,&structsize1)<0){strcpy(host1, "fd1");}else{ // printf("[+]got, ip:%s, port:%d\r\n",inet_ntoa(client1.sin_addr),ntohs(client1.sin_port));strcpy(host1, inet_ntoa(client1.sin_addr));port1=ntohs(client1.sin_port);} if(getpeername(fd2,(struct sockaddr *)&client2,&structsize2)<0){strcpy(host2,"fd2");}else{ // printf("[+]got, ip:%s, port:%d\r\n",inet_ntoa(client2.sin_addr),ntohs(client2.sin_port));strcpy(host2, inet_ntoa(client2.sin_addr));port2=ntohs(client2.sin_port);} printf("[+] Start Transmit (%s:%d <-> %s:%d) ......\r\n\n", host1, port1, host2, port2); maxfd=max(fd1,fd2)+1;memset(read_in1,0,MAXSIZE);memset(read_in2,0,MAXSIZE);memset(send_out1,0,MAXSIZE);memset(send_out2,0,MAXSIZE); timeset.tv_sec=TIMEOUT;timeset.tv_usec=0; while(1){FD_ZERO(&readfd);FD_ZERO(&writefd); FD_SET((UINT)fd1, &readfd);FD_SET((UINT)fd1, &writefd);FD_SET((UINT)fd2, &writefd);FD_SET((UINT)fd2, &readfd); result=select(maxfd,&readfd,&writefd,NULL,×et);if((result<0) && (errno!=EINTR)){printf("[-] Select error.\r\n");break;}else if(result==0){printf("[-] Socket time out.\r\n");break;} if(FD_ISSET(fd1, &readfd)){/* must < MAXSIZE-totalread1, otherwise send_out1 will flow */if(totalread1 < MAXSIZE) {read1=recv(fd1, read_in1, MAXSIZE-totalread1, 0); if((read1==SOCKET_ERROR) || (read1==0)){printf("[-] Read fd1 data error,maybe close?\r\n");break;} memcpy(send_out1+totalread1,read_in1,read1);sprintf(tmpbuf,"\r\nRecv %5d bytes from %s:%d\r\n", read1, host1, port1);printf(" Recv %5d bytes %16s:%d\r\n", read1, host1, port1);makelog(tmpbuf,strlen(tmpbuf));makelog(read_in1,read1);totalread1+=read1;memset(read_in1,0,MAXSIZE);}} if(FD_ISSET(fd2, &writefd)){int err=0;sendcount1=0;while(totalread1>0){send1=send(fd2, send_out1+sendcount1, totalread1, 0);if(send1==0)break;if((send1<0) && (errno!=EINTR)){printf("[-] Send to fd2 unknow error.\r\n");err=1;break;} if((send1<0) && (errno==ENOSPC)) break;sendcount1+=send1;totalread1-=send1; printf(" Send %5d bytes %16s:%d\r\n", send1, host2, port2);} if(err==1) break;if((totalread1>0) && (sendcount1>0)){/* move not sended data to start addr */memcpy(send_out1,send_out1+sendcount1,totalread1);memset(send_out1+totalread1,0,MAXSIZE-totalread1);}elsememset(send_out1,0,MAXSIZE);} if(FD_ISSET(fd2, &readfd)){if(totalread2 < MAXSIZE) {read2=recv(fd2,read_in2,MAXSIZE-totalread2, 0); if(read2==0)break;if((read2<0) && (errno!=EINTR)){printf("[-] Read fd2 data error,maybe close?\r\n\r\n");break;} memcpy(send_out2+totalread2,read_in2,read2);sprintf(tmpbuf, "\r\nRecv %5d bytes from %s:%d\r\n", read2, host2, port2);printf(" Recv %5d bytes %16s:%d\r\n", read2, host2, port2);makelog(tmpbuf,strlen(tmpbuf));makelog(read_in2,read2);totalread2+=read2;memset(read_in2,0,MAXSIZE);}} if(FD_ISSET(fd1, &writefd)){int err2=0;sendcount2=0;while(totalread2>0){send2=send(fd1, send_out2+sendcount2, totalread2, 0);if(send2==0)break;if((send2<0) && (errno!=EINTR)){printf("[-] Send to fd1 unknow error.\r\n");err2=1;break;}if((send2<0) && (errno==ENOSPC)) break;sendcount2+=send2;totalread2-=send2; printf(" Send %5d bytes %16s:%d\r\n", send2, host1, port1);}if(err2==1) break;if((totalread2>0) && (sendcount2 > 0)){/* move not sended data to start addr */memcpy(send_out2, send_out2+sendcount2, totalread2);memset(send_out2+totalread2, 0, MAXSIZE-totalread2);}elsememset(send_out2,0,MAXSIZE);} Sleep(5);} closesocket(fd1);closesocket(fd2);// if(method == 3)// connectnum --; printf("\r\n[+] OK! I Closed The Two Socket.\r\n"); } void getctrlc(int j){    printf("\r\n[-] Received Ctrl+C\r\n");    closeallfd();    exit(0);} void closeallfd(){    int i;         printf("[+] Let me exit ......\r\n");    fflush(stdout);         for(i=3; i<256; i++)    {        closesocket(i);     }         if(fp != NULL)     {        fprintf(fp,"\r\n====== Exit ======\r\n");        fclose(fp);    }         printf("[+] All Right!\r\n");} int create_socket(){     int sockfd;     sockfd=socket(AF_INET,SOCK_STREAM,0);    if(sockfd<0)    {        printf("[-] Create socket error.\r\n");        return(0);    }     return(sockfd); } int create_server(int sockfd,int port){    struct sockaddr_in srvaddr;    int on=1;     memset(&srvaddr, 0, sizeof(struct sockaddr));     srvaddr.sin_port=htons(port);    srvaddr.sin_family=AF_INET;    srvaddr.sin_addr.s_addr=htonl(INADDR_ANY);     setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR, (char*)&on,sizeof(on)); //so I can rebind the port     if(bind(sockfd,(struct sockaddr *)&srvaddr,sizeof(struct sockaddr))<0)    {        printf("[-] Socket bind error.\r\n");        return(0);    }     if(listen(sockfd,CONNECTNUM)<0)    {        printf("[-] Socket Listen error.\r\n");        return(0);    }     return(1);} int client_connect(int sockfd,char* server,int port){    struct sockaddr_in cliaddr;    struct hostent *host;     if(!(host=gethostbyname(server)))    {        printf("[-] Gethostbyname(%s) error:%s\n",server,strerror(errno));        return(0);    }     memset(&cliaddr, 0, sizeof(struct sockaddr));    cliaddr.sin_family=AF_INET;    cliaddr.sin_port=htons(port);    cliaddr.sin_addr=*((struct in_addr *)host->h_addr);     if(connect(sockfd,(struct sockaddr *)&cliaddr,sizeof(struct sockaddr))<0)    {        printf("[-] Connect error.\r\n");        return(0);    }    return(1);} void makelog(char *buffer,int length){    if(fp !=NULL)    {        // fprintf(fp, "%s", buffer);        // printf("%s",buffer);        write(fileno(fp),buffer,length);        // fflush(fp);    }}

Windows7 64+VS2013编译通过的源码：

/*************************************************************************************** PortTrans.cpp - Port Forwarding.** Copyright (C) 2015 HUC All Rights Reserved.** Author : pandas* : * :* Date : 2015-4-9* :* Complie : cl PortTrans.cpp* :* Usage : D:\>PortTrans* : ======================== Port Forwarding Tool V1.00 =======================* :    ========================== Improved by pandas ===========================* :* : [Usage of Port Forwarding:]* : PortTrans - [-log logfile]* :* : [option:]* : -listen* : -tran* : -slave**************************************************************************************/#define _WINSOCK_DEPRECATED_NO_WARNINGS#define  _CRT_SECURE_NO_WARNINGS#include <stdio.h>#include <stdlib.h>#include <winsock2.h>#include <signal.h>#include <errno.h>#include <io.h> #pragma comment(lib, "ws2_32.lib")#define VERSION "1.00"#define TIMEOUT 300#define MAXSIZE 20480#define HOSTLEN 40#define CONNECTNUM 5// define 2 socket structstruct transocket{    SOCKET fd1;    SOCKET fd2;};// define function void ver();void usage(char *prog);void transmitdata(LPVOID data);void getctrlc(int j);void closeallfd();void makelog(char *buffer, int length);void proxy(int port);void bind2bind(int port1, int port2);void bind2conn(int port1, char *host, int port2);void conn2conn(char *host1, int port1, char *host2, int port2);int testifisvalue(char *str);int create_socket();int create_server(int sockfd, int port);int client_connect(int sockfd, char* server, int port);// define GLOBAL variable here//int error;FILE *fp;int method = 0;//int connectnum=0;//************************************************************************************// // function main 主要是处理用户参数输入的问题////************************************************************************************VOID main(int argc, char* argv[]){    char **p;    char sConnectHost[HOSTLEN], sTransmitHost[HOSTLEN];    int iConnectPort = 0, iTransmitPort = 0;    char *logfile = NULL;    errno_t err;    ver();    memset(sConnectHost, 0, HOSTLEN);    memset(sTransmitHost, 0, HOSTLEN);    p = argv;    while (*p)    {        if (_stricmp(*p, "-log") == 0)        {            if (testifisvalue(*(p + 1)))            {                logfile = *(++p);            }            else            {                printf("[-] ERROR: Must supply logfile name.\r\n");                return;            }            //p++;            continue;        }        p++;    }    if (logfile != NULL)    {        //fp = fopen(logfile, "a");        err = fopen_s(&fp, logfile, "a");        if (fp == NULL)        {            printf("[-] ERROR: open logfile");            return;        }        makelog("====== Start ======\r\n", 22);    }    // Win Start Winsock.    WSADATA wsadata;    WSAStartup(MAKEWORD(2, 2), &wsadata);    signal(SIGINT, &getctrlc);    if (argc > 2)    {        if (_stricmp(argv[1], "-listen") == 0 && argc >= 4)        {            iConnectPort = atoi(argv[2]);            iTransmitPort = atoi(argv[3]);            method = 1;        }        else            if (_stricmp(argv[1], "-tran") == 0 && argc >= 5)            {                iConnectPort = atoi(argv[2]);                strncpy_s(sTransmitHost, argv[3], HOSTLEN);                iTransmitPort = atoi(argv[4]);                method = 2;            }            else                if (_stricmp(argv[1], "-slave") == 0 && argc >= 6)                {                    strncpy_s(sConnectHost, argv[2], HOSTLEN);                    iConnectPort = atoi(argv[3]);                    strncpy_s(sTransmitHost, argv[4], HOSTLEN);                    iTransmitPort = atoi(argv[5]);                    method = 3;                }    }    switch (method)    {    case 1:        bind2bind(iConnectPort, iTransmitPort);        break;    case 2:        bind2conn(iConnectPort, sTransmitHost, iTransmitPort);        break;    case 3:        conn2conn(sConnectHost, iConnectPort, sTransmitHost, iTransmitPort);        break;    default:        usage(argv[0]);        break;    }    if (method)    {        closeallfd();    }    WSACleanup();    return;}//************************************************************************************// // print version message////************************************************************************************VOID ver(){    printf("======================== Port Forwarding Tool V%s =======================\r\n", VERSION);    printf("========================== Improved by pandas ===========================\r\n\n");}//************************************************************************************// // print usage message////************************************************************************************VOID usage(char* prog){    printf("[Usage of Packet Transmit:]\r\n");    printf(" %s - [-log logfile]\n\n", prog);    printf("[option:]\n");    printf(" -listen \n");    printf(" -tran \n");    printf(" -slave \n\n");    return;}//************************************************************************************// // test if is value ////************************************************************************************int testifisvalue(char *str){    if (str == NULL) return(0);    if (str[0] == '-') return(0);    return(1);}//************************************************************************************// // LocalHost:ConnectPort transmit to LocalHost:TransmitPort////************************************************************************************void bind2bind(int port1, int port2){    SOCKET fd1, fd2, sockfd1, sockfd2;    struct sockaddr_in client1, client2;    int size1, size2;    HANDLE hThread = NULL;    transocket sock;    DWORD dwThreadID;    if ((fd1 = create_socket()) == 0) return;    if ((fd2 = create_socket()) == 0) return;    printf("[+] Listening port %d ......\r\n", port1);    fflush(stdout);    if (create_server(fd1, port1) == 0)    {        closesocket(fd1);        return;    }    printf("[+] Listen OK!\r\n");    printf("[+] Listening port %d ......\r\n", port2);    fflush(stdout);    if (create_server(fd2, port2) == 0)    {        closesocket(fd2);        return;    }    printf("[+] Listen OK!\r\n");    size1 = size2 = sizeof(struct sockaddr);    while (1)    {        printf("[+] Waiting for Client on port:%d ......\r\n", port1);        if ((sockfd1 = accept(fd1, (struct sockaddr *)&client1, &size1))<0)        {            printf("[-] Accept1 error.\r\n");            continue;        }        printf("[+] Accept a Client on port %d from %s ......\r\n", port1, inet_ntoa(client1.sin_addr));        printf("[+] Waiting another Client on port:%d....\r\n", port2);        if ((sockfd2 = accept(fd2, (struct sockaddr *)&client2, &size2))<0)        {            printf("[-] Accept2 error.\r\n");            closesocket(sockfd1);            continue;        }        printf("[+] Accept a Client on port %d from %s\r\n", port2, inet_ntoa(client2.sin_addr));        printf("[+] Accept Connect OK!\r\n");        sock.fd1 = sockfd1;        sock.fd2 = sockfd2;        hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)transmitdata, (LPVOID)&sock, 0, &dwThreadID);        if (hThread == NULL)        {            TerminateThread(hThread, 0);            return;        }        Sleep(1000);        printf("[+] CreateThread OK!\r\n\n");    }}//************************************************************************************// // LocalHost:ConnectPort transmit to TransmitHost:TransmitPort////************************************************************************************void bind2conn(int port1, char *host, int port2){    SOCKET sockfd, sockfd1, sockfd2;    struct sockaddr_in remote;    int size;    char buffer[1024];    HANDLE hThread = NULL;    transocket sock;    DWORD dwThreadID;    if (port1 > 65535 || port1 < 1)    {        printf("[-] ConnectPort invalid.\r\n");        return;    }    if (port2 > 65535 || port2 < 1)    {        printf("[-] TransmitPort invalid.\r\n");        return;    }    memset(buffer, 0, 1024);    if ((sockfd = create_socket()) == INVALID_SOCKET) return;    if (create_server(sockfd, port1) == 0)    {        closesocket(sockfd);        return;    }    size = sizeof(struct sockaddr);    while (1)    {        printf("[+] Waiting for Client ......\r\n");        if ((sockfd1 = accept(sockfd, (struct sockaddr *)&remote, &size))<0)        {            printf("[-] Accept error.\r\n");            continue;        }        printf("[+] Accept a Client from %s:%d ......\r\n",            inet_ntoa(remote.sin_addr), ntohs(remote.sin_port));        if ((sockfd2 = create_socket()) == 0)        {            closesocket(sockfd1);            continue;        }        printf("[+] Make a Connection to %s:%d ......\r\n", host, port2);        fflush(stdout);        if (client_connect(sockfd2, host, port2) == 0)        {            closesocket(sockfd2);            sprintf_s(buffer, "[SERVER]connection to %s:%d error\r\n", host, port2);            send(sockfd1, buffer, strlen(buffer), 0);            memset(buffer, 0, 1024);            closesocket(sockfd1);            continue;        }        printf("[+] Connect OK!\r\n");        sock.fd1 = sockfd1;        sock.fd2 = sockfd2;        hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)transmitdata, (LPVOID)&sock, 0, &dwThreadID);        if (hThread == NULL)        {            TerminateThread(hThread, 0);            return;        }        Sleep(1000);        printf("[+] CreateThread OK!\r\n\n");    }}//************************************************************************************// // ConnectHost:ConnectPort transmit to TransmitHost:TransmitPort////************************************************************************************void conn2conn(char *host1, int port1, char *host2, int port2){    SOCKET sockfd1, sockfd2;    HANDLE hThread = NULL;    transocket sock;    DWORD dwThreadID;    fd_set fds;    int l;    char buffer[MAXSIZE];    while (1)    {        /*        while(connectnum)        {        if(connectnum < CONNECTNUM)        {        Sleep(10000);        break;        }        else        {        Sleep(TIMEOUT*1000);        continue;        }        }        */        if ((sockfd1 = create_socket()) == 0) return;        if ((sockfd2 = create_socket()) == 0) return;        printf("[+] Make a Connection to %s:%d....\r\n", host1, port1);        fflush(stdout);        if (client_connect(sockfd1, host1, port1) == 0)        {            closesocket(sockfd1);            closesocket(sockfd2);            continue;        }        // fix by bkbll         // if host1:port1 recved data, than connect to host2,port2        l = 0;        memset(buffer, 0, MAXSIZE);        while (1)        {            FD_ZERO(&fds);            FD_SET(sockfd1, &fds);            if (select(sockfd1 + 1, &fds, NULL, NULL, NULL) == SOCKET_ERROR)            {                if (errno== WSAEINTR) continue;                break;            }            if (FD_ISSET(sockfd1, &fds))            {                l = recv(sockfd1, buffer, MAXSIZE, 0);                break;            }            Sleep(5);        }        if (l <= 0)        {            printf("[-] There is a error...Create a new connection.\r\n");            continue;        }        while (1)        {            printf("[+] Connect OK!\r\n");            printf("[+] Make a Connection to %s:%d....\r\n", host2, port2);            fflush(stdout);            if (client_connect(sockfd2, host2, port2) == 0)            {                closesocket(sockfd1);                closesocket(sockfd2);                continue;            }            if (send(sockfd2, buffer, l, 0) == SOCKET_ERROR)            {                printf("[-] Send failed.\r\n");                continue;            }            l = 0;            memset(buffer, 0, MAXSIZE);            break;        }        printf("[+] All Connect OK!\r\n");        sock.fd1 = sockfd1;        sock.fd2 = sockfd2;        hThread = CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)transmitdata, (LPVOID)&sock, 0, &dwThreadID);        if (hThread == NULL)        {            TerminateThread(hThread, 0);            return;        }        // connectnum++;        Sleep(1000);        printf("[+] CreateThread OK!\r\n\n");    }}//************************************************************************************// // Socket Transmit to Socket////************************************************************************************void transmitdata(LPVOID data){    SOCKET fd1, fd2;    transocket *sock;    struct timeval timeset;    fd_set readfd, writefd;    int result, i = 0;    char read_in1[MAXSIZE], send_out1[MAXSIZE];    char read_in2[MAXSIZE], send_out2[MAXSIZE];    int read1 = 0, totalread1 = 0, send1 = 0;    int read2 = 0, totalread2 = 0, send2 = 0;    int sendcount1, sendcount2;    int maxfd;    struct sockaddr_in client1, client2;    int structsize1, structsize2;    char host1[20], host2[20];    int port1 = 0, port2 = 0;    char tmpbuf[100];    sock = (transocket *)data;    fd1 = sock->fd1;    fd2 = sock->fd2;    memset(host1, 0, 20);    memset(host2, 0, 20);    memset(tmpbuf, 0, 100);    structsize1 = sizeof(struct sockaddr);    structsize2 = sizeof(struct sockaddr);    if (getpeername(fd1, (struct sockaddr *)&client1, &structsize1)<0)    {        strcpy_s(host1, "fd1");    }    else    {        // printf("[+]got, ip:%s, port:%d\r\n",inet_ntoa(client1.sin_addr),ntohs(client1.sin_port));        strcpy_s(host1, inet_ntoa(client1.sin_addr));        port1 = ntohs(client1.sin_port);    }    if (getpeername(fd2, (struct sockaddr *)&client2, &structsize2)<0)    {        strcpy_s(host2, "fd2");    }    else    {        // printf("[+]got, ip:%s, port:%d\r\n",inet_ntoa(client2.sin_addr),ntohs(client2.sin_port));        strcpy_s(host2, inet_ntoa(client2.sin_addr));        port2 = ntohs(client2.sin_port);    }    printf("[+] Start Transmit (%s:%d <-> %s:%d) ......\r\n\n", host1, port1, host2, port2);    maxfd = max(fd1, fd2) + 1;    memset(read_in1, 0, MAXSIZE);    memset(read_in2, 0, MAXSIZE);    memset(send_out1, 0, MAXSIZE);    memset(send_out2, 0, MAXSIZE);    timeset.tv_sec = TIMEOUT;    timeset.tv_usec = 0;    while (1)    {        FD_ZERO(&readfd);        FD_ZERO(&writefd);        FD_SET((UINT)fd1, &readfd);        FD_SET((UINT)fd1, &writefd);        FD_SET((UINT)fd2, &writefd);        FD_SET((UINT)fd2, &readfd);        result = select(maxfd, &readfd, &writefd, NULL, ×et);        if ((result<0) && (errno!= EINTR))        {            printf("[-] Select error.\r\n");            break;        }        else if (result == 0)        {            printf("[-] Socket time out.\r\n");            break;        }        if (FD_ISSET(fd1, &readfd))        {            /* must < MAXSIZE-totalread1, otherwise send_out1 will flow */            if (totalread1 < MAXSIZE) {                read1 = recv(fd1, read_in1, MAXSIZE - totalread1, 0);                if ((read1 == SOCKET_ERROR) || (read1 == 0))                {                    printf("[-] Read fd1 data error,maybe close?\r\n");                    break;                }                memcpy(send_out1 + totalread1, read_in1, read1);                sprintf_s(tmpbuf, "\r\nRecv %5d bytes from %s:%d\r\n", read1, host1, port1);                printf(" Recv %5d bytes %16s:%d\r\n", read1, host1, port1);                makelog(tmpbuf, strlen(tmpbuf));                makelog(read_in1, read1);                totalread1 += read1;                memset(read_in1, 0, MAXSIZE);            }        }        if (FD_ISSET(fd2, &writefd))        {            int err = 0;            sendcount1 = 0;            while (totalread1>0)            {                send1 = send(fd2, send_out1 + sendcount1, totalread1, 0);                if (send1 == 0)break;                if ((send1<0) && (errno != EINTR))                {                    printf("[-] Send to fd2 unknow error.\r\n");                    err = 1;                    break;                }                if ((send1<0) && (errno == ENOSPC)) break;                sendcount1 += send1;                totalread1 -= send1;                printf(" Send %5d bytes %16s:%d\r\n", send1, host2, port2);            }            if (err == 1) break;            if ((totalread1>0) && (sendcount1>0))            {                /* move not sended data to start addr */                memcpy(send_out1, send_out1 + sendcount1, totalread1);                memset(send_out1 + totalread1, 0, MAXSIZE - totalread1);            }            else                memset(send_out1, 0, MAXSIZE);        }        if (FD_ISSET(fd2, &readfd))        {            if (totalread2 < MAXSIZE) {                read2 = recv(fd2, read_in2, MAXSIZE - totalread2, 0);                if (read2 == 0)break;                if ((read2<0) && (errno != EINTR))                {                    printf("[-] Read fd2 data error,maybe close?\r\n\r\n");                    break;                }                memcpy(send_out2 + totalread2, read_in2, read2);                sprintf_s(tmpbuf, "\r\nRecv %5d bytes from %s:%d\r\n", read2, host2, port2);                printf(" Recv %5d bytes %16s:%d\r\n", read2, host2, port2);                makelog(tmpbuf, strlen(tmpbuf));                makelog(read_in2, read2);                totalread2 += read2;                memset(read_in2, 0, MAXSIZE);            }        }        if (FD_ISSET(fd1, &writefd))        {            int err2 = 0;            sendcount2 = 0;            while (totalread2>0)            {                send2 = send(fd1, send_out2 + sendcount2, totalread2, 0);                if (send2 == 0)break;                if ((send2<0) && (errno != EINTR))                {                    printf("[-] Send to fd1 unknow error.\r\n");                    err2 = 1;                    break;                }                if ((send2<0) && (errno == ENOSPC)) break;                sendcount2 += send2;                totalread2 -= send2;                printf(" Send %5d bytes %16s:%d\r\n", send2, host1, port1);            }            if (err2 == 1) break;            if ((totalread2>0) && (sendcount2 > 0))            {                /* move not sended data to start addr */                memcpy(send_out2, send_out2 + sendcount2, totalread2);                memset(send_out2 + totalread2, 0, MAXSIZE - totalread2);            }            else                memset(send_out2, 0, MAXSIZE);        }        Sleep(5);    }    closesocket(fd1);    closesocket(fd2);    // if(method == 3)    // connectnum --;    printf("\r\n[+] OK! I Closed The Two Socket.\r\n");}void getctrlc(int j){    printf("\r\n[-] Received Ctrl+C\r\n");    closeallfd();    exit(0);}void closeallfd(){    int i;    printf("[+] Let me exit ......\r\n");    fflush(stdout);    for (i = 3; i<256; i++)    {        closesocket(i);    }    if (fp != NULL)    {        fprintf(fp, "\r\n====== Exit ======\r\n");        fclose(fp);    }    printf("[+] All Right!\r\n");}int create_socket(){    int sockfd;    sockfd = socket(AF_INET, SOCK_STREAM, 0);    if (sockfd<0)    {        printf("[-] Create socket error.\r\n");        return(0);    }    return(sockfd);}int create_server(int sockfd, int port){    struct sockaddr_in srvaddr;    int on = 1;    memset(&srvaddr, 0, sizeof(struct sockaddr));    srvaddr.sin_port = htons(port);    srvaddr.sin_family = AF_INET;    srvaddr.sin_addr.s_addr = htonl(INADDR_ANY);    setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (char*)&on, sizeof(on)); //so I can rebind the port    if (bind(sockfd, (struct sockaddr *)&srvaddr, sizeof(struct sockaddr))<0)    {        printf("[-] Socket bind error.\r\n");        return(0);    }    if (listen(sockfd, CONNECTNUM)<0)    {        printf("[-] Socket Listen error.\r\n");        return(0);    }    return(1);}int client_connect(int sockfd, char* server, int port){    struct sockaddr_in cliaddr;    struct hostent *host;    if (!(host = gethostbyname(server)))    {        printf("[-] Gethostbyname(%s) error:%s\n", server, strerror(errno));        return(0);    }    memset(&cliaddr, 0, sizeof(struct sockaddr));    cliaddr.sin_family = AF_INET;    cliaddr.sin_port = htons(port);    cliaddr.sin_addr = *((struct in_addr *)host->h_addr);    if (connect(sockfd, (struct sockaddr *)&cliaddr, sizeof(struct sockaddr))<0)    {        printf("[-] Connect error.\r\n");        return(0);    }    return(1);}void makelog(char *buffer, int length){    if (fp != NULL)    {        _write(_fileno(fp), buffer, length);    }}

注意，VS2013编译出来的程序在其他计算机上运行时，可能出现如下问题：

这是由于需要MSVCR120.dll这个动态链接库来支持C函数库和C++的STL标准库。对于这个问题的解决方法是：可以把C/C++运行时库MSVCR120编译到你的exe里，这样你的程序复制到任意windows上就能直接运行了。项目 - 属性 - 配置属性 - C/C++ - 代码生成 - 运行库 - 多线程(/MT)。这样生成的EXE会增大一些，取决于你用到了多少库函数。具体设置如下图所示：

最后，附上效果图一张：

采用这种方式进行端口转发，其实速度有些慢，有时候会比较卡。对于Web端口转发工具及HTTP版本的LCX，后续我再分析一下。

      以上源码仅供学习之用，请不要用于非法途径。

执行方法:

首先生成一个批处理文件

start 3389.exe -listen 51 33891

start 3389.exe -slave 111.111.111.111 51 127.0.0.1 3390

第一行的中的51是本地监听端口,33891是可供外部访问端口

第二行的111.111.111.111是本机IP地址 51 到local的3390端口进行转发