I am new to FTP\SFTP components, and am attempting to use your Sample Winforms application to connect to a secure public ftp server. I get the same error in your example application that I got in my application, which is "Key exchange failed. Error while sending packet" I can use coreftp lite to connect and navigate just fine. The first time it connects, it asks me to accept their key. Other than that, it works just like any other FTP program. I am not given a pre-shared key or any of that mess. Using your example, I chose verbose logging and got the following:
14:39:16.206 Debug SSH: Negotiation failed: Rebex.Net.SshException: Key exchange failed. Error while sending packet. ---> Rebex.Net.SshException: Error while sending packet. ---> System.Net.Sockets.SocketException: An established connection was aborted by the software in your host machine
at System.Net.Sockets.Socket.Send(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags)
at Rebex.Net.ProxySocket.Send(Byte[] buffer, Int32 offset, Int32 size, SocketFlags socketFlags)
at Rebex.Net.SshSession.1685053200(11634889349 , Boolean )
--- End of inner exception stack trace ---