RakNet ... 이런 네트워크 라이브러리도 있군요..

http://www.rakkarsoft.com

RakNet is more than just a reliable UDP library.

Download 3.0.

Licensing

Licensing is only required on your application's commercial release. All versions include full source. Non-profit applications or engines. You can use RakNet for free under the Creative Commons Attribution - NonCommercial 2.5 license*. . Single application license. A Single Application license* applies to commercial software sold both online and retail. You may download RakNet immediately and are only required to pay when you ship your product. At that time you choose how much to pay based on what you can afford and how much value you feel RakNet has brought to you. Site licenses and commercial engine development. An unlimited application Engine License* applies to commercial software sold using any distribution model and also allows resale of your engine. You may use RakNet as long as you wish during development. When you wish to sell your engine or release your product, you may purchase a license at a fixed fee of $5000. * Third party libraries are included in the download to facilitate sample code. These libraries are included only for convenience and have their own, separate, licensing agreements. These libraries are not required to use RakNet.