code: public boolean startSubsystem(String subsystem) throws SshException {
  
  		ByteArrayWriter request = new ByteArrayWriter();
  		try {
  
  			request.writeString(subsystem);
  			boolean success = sendRequest("subsystem", true,
  					request.toByteArray());
  			if (success) {
  				EventServiceImplementation.getInstance().fireEvent(
  						(new Event(this,
  								J2SSHEventCodes.EVENT_SUBSYSTEM_STARTED, true))
  								.addAttribute(
  										J2SSHEventCodes.ATTRIBUTE_COMMAND,
  										subsystem));
  			} else {
  				EventServiceImplementation
  						.getInstance()
  						.fireEvent(
  								(new Event(
  										this,
  										J2SSHEventCodes.EVENT_SUBSYSTEM_STARTED,
  										false)).addAttribute(
  										J2SSHEventCodes.ATTRIBUTE_COMMAND,
  										subsystem));
  			}
  
  			return success;
  		} catch (IOException ex) {
  			throw new SshException(ex, SshException.INTERNAL_ERROR);
  		} finally {
  			try {
  				request.close();
  			} catch (IOException e) {
  			}
  		}
  
  	}
docs: SSH2 supports special subsystems that are identified by a name rather
  than a command string, an example of an SSH2 subsystem is SFTP.
  
  @param subsystem
  the name of the subsystem, for example "sftp"
  @return <code>true</code> if the subsystem was started, otherwise
  <code>false</code>
  @throws SshException