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IP Packet Redirector
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 | LowerAdapter - A logical interface to the "real" adapter that the NDIS IM driver binds to at it's lower "protocol" edge. |
| Virtual Adapter - The a logical interface associated with the virtual adapter that the NDIS IM driver presents to other protocols at its upper "miniport" edge. |
Here is an illustration of the Packet Redirector NDIS IM driver when it is installed between TCP/IP and a miniport driver:
The API provided with the Packet Redirector allows a Win32 application to open a handle to either (or both) of these adapter interfaces:
| PCASIM_OpenLowerAdapter - Opens a handle associated with the lower or "real" adapter using the "Adapter Name". |
| PCASIM_OpenVirtualAdapter - Opens a handle associated with the upper or "virtual" adapter using the "AdapterName". |
One can read and write on either of these adapter handles using these API functions:
| PCASIM_ReadOnAdapter - Reads a selected packet on the specified handle. |
| PCASIM_WriteOnAdapter - Writes a packet on the specified handle. |
I/O on Packet Redirector Lower Adapter Handle
It should be easy to understand read/write operations on a PCASIM lower adapter handle. | Writes on a PCASIM lower adapter handle are
translated to NdisSend calls to the lower "real" adapter and result in
packets being sent on the network. |
| Reads on the lower adapter handle allow the Win32 application to read a selected packet that was being received or indicated from the lower adapter. |
This is illustrated below:
I/O on Packet Redirector Virtual Adapter Handle
However, in this case the behavior is "upside-down":
It should be easy to understand read/write operations on a PCASIM lower adapter handle.
| Writes |
| Reads |
This is illustrated below:
A mechanism is provided that allows the Win32 application to pass a filter to the driver to specify which IP packets can be read. The filter is list of IP Source/Destination address ranges and an "action" to be performed on packets that match the filter criteria. The actions can be combinations of:
| BLOCK - Have the NDIS IM driver drop the matching packet from the normal packet flow. |
| REDIRECT - Have the NDIS IM driver pass a copy of the received packet to the Win32 application through the PCASIM_ReadOnPacket mechanism. |
For example, the combination of BLOCK and REDIRECT actions cause a matching packet to be be diverted up to the Win32 application for processing. The REDIRECT action allows the Win32 application to monitor the packet while allowing it to also pass up to higher level protocols for ordinary processing.
| Driver buffering (queuing) of received packets by the NDIS IM driver. |
Here are the current test applications provided to test the IP Packet Redirector sample:
| PRTest1 - Illustrates setting an IP Filter to block sending of selected IP packets. |
| PRTest2 - Monitors selected IP packets as they are being sent. |
| PRTest3 - Redirects selected PING requests to Win32 where they are echoed. |
| PRTest4 - Monitors reception of selected IP packets as they are received. |
| PRTest5 - All IP packets sent or received are looped through a Win32 application. |
These are Win32 console applications.
For some tests you must use Ctrl-C to exit the program. This is a simple way to terminate the application and has the additional virtue of testing the driver I/O cancellation and cleanup logic.
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