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A user-mode bridge based onNpcap/WinPcap

1. GetWinPcap 4.1.2 Developer's Pack
2. BuildUserBridge.sln withVisual Studio 2013

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

1. Network adapter 'Microsoft' on local host2. Network adapter 'Intel(R) 82574L Gigabit Network Connection' on local host3. Network adapter 'MS NDIS 6.0 LoopBack Driver' on local hostSpecify filter (hit return for no filter):

PressEnter.

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

Type in the index of the first adapter and pressEnter.

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

Type in the index of the second adapter and pressEnter.

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. LineLen: 142 means there's a packet with 142 bytes is handled.

If you want all received traffic onAdapter A seems like to be received onAdapter B, and all traffic sent out fromAdapter B to be actually sent out fromAdapter A, you can realize this by usingUserBridge andNpcap. You need to do two steps:

1. SpecifyAdapter B as aSend-to-Rx adapter inNpcap (seev0.05-r6 andv0.05-r7 forSend-to-Rx's details).
2. SpecifyAdapter A as the first interface andAdapter B as the second interface inUserBridge.

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

1. SpecifyAdapter A as both aBlock-Rx and aSend-to-Rx adapter inNpcap (seev0.05-r11 forBlock-Rx's details).
2. SpecifyAdapter A as both the first interface and second interface inUserBridge.