Based on suggestion by Saint_pl:
I found probably better solution - similar to SharpPcap. It's Pcap.Net - .NET wrapper for WinPcap. Now I can modify my packets whatever I want.
I have some resources for you that maybe helpful. I don't try that solutions in Windows 7 but maybe it contains some good info to start.
Raw Ethernet Packet Manipulation or mirror on CodeProject
This purpose of this article is to explain how to send a raw Ethernet packet using C# on a Microsoft platform. A raw Ethernet packet is the complete Layer 2 network frame that is sent to the physical wire. Sending a frame like this allows you to manipulate the target and source MAC addresses and the Layer 3 protocol fields.
Also some info on raw sockets (just in case you interesting too):
Client (and Server) Sockets Communication take a look on whole chapter but here key parts:
- C# Raw UDP Socket Program Example
- C# Raw Socket Ping Program Example part A | part B
- All examples
Not sending packets but maybe interesting: A Network Sniffer in C#, SharpPcap - A Packet Capture Framework for .NET
