code: public void setPreferredMacCS(String name) throws SshException {
  
  		if (name == null)
  			return;
  
  		if (macCS.contains(name)) {
  			prefMacCS = name;
  			setMacPreferredPositionCS(name, 0);
  		} else {
  			throw new SshException(name + " is not supported",
  					SshException.UNSUPPORTED_ALGORITHM);
  		}
  	}
docs: Set the preferred mac for the Client->Server stream.
  
  @param name
  @throws SshException