t = paramiko.Transport(('192.168.56.102', 22))
t.connect(username='vagrant', password='vagrant')
chan = t.open_session()
chan.get_pty()
chan.invoke_subsystem('sftp')
chan.exec_command('sudo su')
sftp = paramiko.SFTPClient.from_transport(t)

paramiko.ssh_exception.SSHException: Channel closed.
DEBUG:paramiko.transport:EOF in transport thread

chan.exec_command('sudo su -c /bin/sftp-server')