UserBridge

A user-mode bridge based on Npcap/WinPcap

Build

1. Get WinPcap 4.1.2 Developer's Pack
2. Build UserBridge.sln with Visual Studio 2013

Usage

Launch the executable UserBridge.exe, you will see a list of adapters like:

1. Network adapter 'Microsoft' on local host
2. Network adapter 'Intel(R) 82574L Gigabit Network Connection' on local host
3. Network adapter 'MS NDIS 6.0 LoopBack Driver' on local host

Specify filter (hit return for no filter):

Press Enter.

Enter the number of the first interface to use (1-3):

Type in the index of the first adapter and press Enter.

Enter the number of the second interface to use (1-3):

Type in the index of the second adapter and press Enter.

Start bridging the two adapters...

If the bridging succeeds, you will see a lot of lines coming up in the prompt like:

>> Len: 142
>> Len: 94
>> Len: 142
>> Len: 142
>> Len: 94
<< Len: 142
<< Len: 142
<< Len: 142
<< Len: 94
<< Len: 142
<< Len: 142
<< Len: 142
<< Len: 142
<< Len: 142

All these lines show the traffic flow handled by the bridge. Line Len: 142 means there's a packet with 142 bytes is handled.

How to make a bridge?

If you want all received traffic on Adapter A seems like to be received on Adapter B, and all traffic sent out from Adapter B to be actually sent out from Adapter A, you can realize this by using UserBridge and Npcap. You need to do two steps:

1. Specify Adapter B as a Send-to-Rx adapter in Npcap (see v0.05-r6 and v0.05-r7 for Send-to-Rx's details).
2. Specify Adapter A as the first interface and Adapter B as the second interface in UserBridge.

How to make a firewall?

If you want all received traffic on Adapter A get filtered by UserBridge, and drop the packets you don't want like a firewall. You need to do two steps:

1. Specify Adapter A as both a Block-Rx and a Send-to-Rx adapter in Npcap (see v0.05-r11 for Block-Rx's details).
2. Specify Adapter A as both the first interface and second interface in UserBridge.