I need to implement an FTP service inside my .NET application (running as a Windows Service) and have not had much luck finding good/current source code or vendors. Ideally it needs to be able to respond to the basic FTP Protocol and accept the data stream from an upload via a stream, enabling me to process the data as it is being received (think on the fly hashing).
I need to be able to integrate it into my service because it will stack on top of our current code base with an existing custom TCP/IP communication protocol. I don’t want to write (and then spend time debugging and performance testing) my own protocol, or implementation.
I have already found plenty of ftp client implementations, I just need an acceptable server solution.
There is an article about rolling your own FTP server in C# here. It’s a bit old, but it might be complete enough for your requirements.
If you can get away from the need to process inbound data on-the-fly, I’d suggest just using an off-the-shelf FTP server (maybe even IIS), and process the received files from a folder. Your service could easily monitor this folder for new files. The other benefit of this is that files could be received even if your service is not running or restarting, and testing would be easier as you can drop your own files into the monitored folder.
Good luck!