IMPORTANT NOTICE: Code for this project is no longer maintained, and is released to the public domain. The NAT testing and classification server, however, will continue to operate. The concepts behind this work are being rolled in ICE-TCP, which we expect will find it's way into various open-source libraries such as PJNatH and libJingle. Feel free to contact Saikat if you have general questions about TCP NAT traversal.

libnutss

• Binaries: download
• Source: srpm bz2 zip
• Examples: nutssping other examples
• Docs: API reference

NAT Testing Software

• Client: Windows, Linux
• Server: Linux
• Running the Client
• Client Documentation
• Server Documentation
• Frequently Asked Questions
• Survey Results

1. I get the error wpcap.dll not found. You need to install WinPcap.
2. How do I determine what interfaces I have? Pass the command line option -i help
3. I have multiple network interfaces and STUNT always reports an error. Pass the command line option -i help to list the interfaces and then execute STUNT with -bftro output -i <num> where <num> is the number of the interface that connects you to the internet.
4. I get the error -- "Need root privileges". On Windows, you need to run the NAT testing utility while logged in as an Administrator. On Linux, you need to run it with an effective user ID of 0. The NAT testing utility needs these privileges since it needs to see the packets sent by the operating system.
5. I see lots of errors. Is something wrong? Intermittent errors may occur, if so, try running the client after a while. If the error is persistent then there may be a problem. Please run the client with the -vv option, redirect the output to a file and contact saikat@cs.cornell.edu with a copy of the output for diagnosis.
6. How much CPU time and bandwidth does this use? The client uses virtually 0 CPU time since there is negligible processing required. It uses less than 0.05 kbps on average since TCP connection establishment involves very few packets and very little data is transferred between clients and servers.
7. The test always errors while testing bindings. Some NATs, like Open BSD, enforce TIMED-WAIT state after a connection is closed by a RST even if the client operation system doesn't. Try passing the command line option --binding-interval 120. This will make the test take longer, but it will hopefully succeed.