Keyboard Interactive Authentication Fails

[byteoctopus]

When attempting to connect to a server which requires keyboard interactive authentication the following error occurs:

No SSH key file selected, using password auth instead.
Please enter password:
Failed to authenticate using password, falling back to next auth mechanism if available.

Unhandled Exception: System.ArgumentNullException: String reference not set to an instance of a String.
Parameter name: s
   at Renci.SshNet.KeyboardInteractiveAuthenticationMethod.Authenticate(Session session)
   at Renci.SshNet.AuthenticationMethod.Renci.SshNet.IAuthenticationMethod.Authenticate(ISession session)
   at Renci.SshNet.ClientAuthentication.TryAuthenticate(ISession session, AuthenticationState authenticationState, String[] allowedAuthenticationMethods, SshAuthenticationException& authenticationException)
   at Renci.SshNet.ClientAuthentication.Authenticate(IConnectionInfoInternal connectionInfo, ISession session)
   at Renci.SshNet.ConnectionInfo.Authenticate(ISession session, IServiceFactory serviceFactory)
   at Renci.SshNet.Session.Connect()
   at Renci.SshNet.BaseClient.Connect()
   at SSHFS.CLI.Program.AttemptConnection(String authType, ConnectionInfo connInfo, String path) in C:\projects\win-sshfs\Sshfs\SSHFS.CLI\Program.cs:line 160
   at SSHFS.CLI.Program.<>c__DisplayClass1_0.<Start>b__0(ValueTuple`2 auth) in C:\projects\win-sshfs\Sshfs\SSHFS.CLI\Program.cs:line 79
   at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
   at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source, Func`2 predicate)
   at SSHFS.CLI.Program.Start(Options options) in C:\projects\win-sshfs\Sshfs\SSHFS.CLI\Program.cs:line 78
   at CommandLine.ParserResultExtensions.WithParsed[T](ParserResult`1 result, Action`1 action)
   at SSHFS.CLI.Program.Main(String[] args) in C:\projects\win-sshfs\Sshfs\SSHFS.CLI\Program.cs:line 70

[masaeedu]

Hi there. What is your command line invocation?

[byteoctopus]

sshfs -d z -r /home/user -h domain.xyz -u user -x

[masaeedu]

So you entered the password manually, and it failed? Could you try echo "yourpass" | ...?

[byteoctopus]

Yes, I manually entered the password.

Using echo "password" | sshfs -d z -r /home/user -h domain.xyz -u user -x results in

Failed to authenticate using password, falling back to next auth mechanism if available.
Failed to authenticate using keyboard-interactive, falling back to next auth mechanism if available.

Unhandled Exception: System.InvalidOperationException: Could not connect to server with any known authentication mechanism
   at SSHFS.CLI.Program.Start(Options options) in C:\projects\win-sshfs\Sshfs\SSHFS.CLI\Program.cs:line 83
   at CommandLine.ParserResultExtensions.WithParsed[T](ParserResult`1 result, Action`1 action)
   at SSHFS.CLI.Program.Main(String[] args) in C:\projects\win-sshfs\Sshfs\SSHFS.CLI\Program.cs:line 70

[masaeedu]

It seems like authentication is failing, at least for the user you're attempting to log in as. Have you tried using regular ssh to log in with the same credentials?

[byteoctopus]

Yes, ssh logins work via linux/putty/cygwin. The server prompts the user for a two factor authentication option (phone, mobile app, etc.) and logs in once that gets approved.

[masaeedu]

@byteoctopus I see. That's probably the issue; right now the "keyboard interactive" login isn't actually interactive, the tool just reads a password and tries to use it for both interactive and non-interactive password login. I'll see about using the keyboard interactive login API to allow you to make it actually interactive (so that e.g. you can wait for 2-factor) on Monday. If you want to take a crack at it, the relevant code is in:

• https://github.com/masaeedu/win-sshfs/blob/master/Sshfs/SSHFS.CLI/Program.cs#L108
• https://github.com/masaeedu/win-sshfs/blob/master/Sshfs/SSHFS.CLI/Program.cs#L140

Instead of passing in a password read from stdin, we'd need to present an interactive REPL using the AuthenticationPrompt handler.

[byteoctopus]

Ah that makes sense. I'll give it a try. Thanks!