SFTP version negotiation

[Henrick Hellström <henrick%streamsec.se@localhost>]

Just a thought...

What happens if a SFTP server supports v3 and v4, and a client that 
supports v3 and v6 only connects?

According to the latest draft, they are supposed to start v4, since the 
client will send v6 and the server supports at most v4, and v4 is the 
least of these two numbers.

Quoted from draft 05:

4. Protocol Initialization

   When the file transfer protocol starts, the client first sends a
   SSH_FXP_INIT (including its version number) packet to the server. The
   server responds with a SSH_FXP_VERSION packet, supplying the lowest
   of its own and the client's version number.  Both parties should from
   then on adhere to particular version of the protocol.