以下是在VB中截获WIN2000下TCP/IP包的源代码，在VB6.0,win2000下测试通过，需要注意的地方是，1.必须和本地的一块网卡,2.每次获取数据后必须有一段延时。3.数据取到之后放在Buff的数组中。4.把以下的代码放在一个模块中就可以了。

'-----------------------------代码开始--------------------------------------------------
Declare Function bind Lib "ws2_32.dll" (ByVal s As Long, addr As SOCK_ADDR, ByVal namelen As Long) As Long
Declare Function closesocket Lib "ws2_32.dll" (ByVal s As Long) As Long
Declare Function connect Lib "ws2_32.dll" (ByVal s As Long, name As SOCK_ADDR, ByVal namelen As Integer) As Long
Declare Function inet_addr Lib "ws2_32.dll" (ByVal cp As String) As Long
Declare Function htons Lib "ws2_32.dll" (ByVal hostshort As Integer) As Integer
Declare Function recv Lib "ws2_32.dll" (ByVal s As Long, buffer As Any, ByVal length As Long, ByVal flags As Long) As Long
Declare Function send Lib "ws2_32.dll" (ByVal s As Long, buffer As Any, ByVal length As Long, ByVal flags As Long) As Long
Declare Function shutdown Lib "ws2_32.dll" (ByVal s As Long, ByVal how As Long) As Long
Declare Function ioctlsocket Lib "ws2_32.dll" (ByVal s As Long, ByVal v As Long, ut As Long) As Long
Declare Function socket Lib "ws2_32.dll" (ByVal af As Long, ByVal type_specification As Long, ByVal protocol As Long) As Long
Declare Function WSACancelBlockingCall Lib "ws2_32.dll" () As Long
Declare Function WSACleanup Lib "ws2_32.dll" () As Long
Declare Function WSAGetLastError Lib "ws2_32.dll" () As Long
Declare Function WSAStartup Lib "ws2_32.dll" (ByVal wVersionRequired As Integer, wsData As WSA_DATA) As Long
Declare Function WSASocketA Lib "ws2_32.dll" (ByVal af As Long, ByVal type1 As Long, ByVal protocol As Long, lpProtocolInfo As Long, g As Long, ByVal dwFlags As Long)
Declare Function WSAIoctl Lib "ws2_32.dll" (ByVal s As Long, ByVal dwIoControlCode As Long, lpvInBuffer As Long, ByVal cbInBuffer As Long, lpvOutBuffer As Long, ByVal cbOutBuffer As Long, lpcbBytesReturned As Long, lpOverlapped As Long, lpCompletionRoutine As Long) As Long

Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (Destination As Any, Source As Any, ByVal length As Long)

Public Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)

Public Const WSADESCRIPTION_LEN = 256
Public Const WSASYS_STATUS_LEN = 128

Type WSA_DATA
　 wVersion As Integer
　 wHighVersion As Integer
　 strDescription(WSADESCRIPTION_LEN + 1) As Byte
　 strSystemStatus(WSASYS_STATUS_LEN + 1) As Byte
　 iMaxSockets As Integer
　 iMaxUdpDg As Integer
　 lpVendorInfo As Long
End Type

Type IN_ADDR
　 S_addr As Long
End Type

Type SOCK_ADDR
　 sin_family As Integer
　 sin_port As Integer
　 sin_addr As IN_ADDR
　 sin_zero(0 To 7) As Byte
End Type

Type IPHeader
　 lenver As Byte
　 tos As Byte
　 len As Integer
　 ident As Integer
　 flags As Integer
　 ttl As Byte
　 proto As Byte
　 checksum As Integer
　 sourceIP As Long
　 destIP As Long
End Type

Const AF_INET = 2
Const SOCK_RAW = 3
Const IPPROTO_IP = 0
Const IPPROTO_TCP = 6
Const IPPROTO_UDP = 17
Const MAX_PACK_LEN = 65535
Const SOCKET_ERROR = -1&

Private mwsaData As WSA_DATA
Private m_hSocket As Long

Private msaLocalAddr As SOCK_ADDR
Private msaRemoteAddr As SOCK_ADDR

Sub Main()
　 Dim nResult As Long

　 nResult = WSAStartup(&H202, mwsaData)
　 If nResult <> WSANOERROR Then
　　 MsgBox "Error en WSAStartup"
　　 Exit Sub
　 End If

　 m_hSocket = socket(AF_INET, SOCK_RAW, IPPROTO_IP)
　 If (m_hSocket = INVALID_SOCKET) Then
　　 MsgBox "Error in socket"
　　 Exit Sub
　 End If

　 msaLocalAddr.sin_family = AF_INET
　 msaLocalAddr.sin_port = 0
　 msaLocalAddr.sin_addr.S_addr = inet_addr("192.168.1.125") '这里需要你自己的网卡的IP地址

　 nResult = bind(m_hSocket, msaLocalAddr, Len(msaLocalAddr))
　 If (nResult = SOCKET_ERROR) Then
　　 MsgBox "Error in bind"
　　 Exit Sub
　 End If

　 Dim InParamBuffer As Long
　 Dim BytesRet As Long
　 BytesRet = 0
　 InParamBuffer = 1

　 nResult = ioctlsocket(m_hSocket, &H98000001, 1)

　 If nResult <> 0 Then
　　 MsgBox "ioctlsocket"
　　 Exit Sub
　 End If

　 Dim strData As String
　 Dim nReceived As Long

　 '截获来的数据放在BUFF里面
　 Dim Buff(0 To MAX_PACK_LEN) As Byte
　 Dim IPH As IPHeader

　 Do Until False '这个例子里，一直获取
　 DoEvents
　 nResult = recv(m_hSocket, Buff(0), MAX_PACK_LEN, 0)
　 If nResult = SOCKET_ERROR Then
　　 MsgBox "Error in RecvData::recv"
　　 Exit Do
　 End If
　 CopyMemory IPH, Buff(0), Len(IPH) '为了访问方便
　 Select Case IPH.proto
　　 Case IPPROTO_TCP
　　　 'frmHookTcpip.Text1.SelText = HexIp2DotIp(IPH.sourceIP)
　　　 'frmHookTcpip.Text1.SelText = " -----> "
　　　 'frmHookTcpip.Text1.SelText = HexIp2DotIp(IPH.destIP)
　　　 'frmHookTcpip.Text1.SelText = vbCrLf
　　　 Debug.Print HexIp2DotIp(IPH.sourceIP) & " -----> " & HexIp2DotIp(IPH.destIP)
　　　 End Select
　　 Loop

　 nResult = shutdown(m_hSocket, 2)
　 nResult = closesocket(m_hSocket)
　 nResult = WSACancelBlockingCall
　 nResult = WSACleanup
End Sub

Function HexIp2DotIp(ByVal ip As Long) As String
　 Dim s As String, p1 As String, p2 As String, p3 As String, p4 As String
　 s = Right("00000000" & Hex(ip), 8)
　 p1 = Val("&h" & Mid(s, 1, 2))
　 p2 = Val("&h" & Mid(s, 3, 2))
　 p3 = Val("&h" & Mid(s, 5, 2))
　 p4 = Val("&h" & Mid(s, 7, 2))
　 HexIp2DotIp = p4 & "." & p3 & "." & p2 & "." & p1
　 End Function
'-----------------------------代码结束--------------------------------------------------