Schlepptop:~ Jakob$ sudo port selfupdate
--->  Updating MacPorts base sources using rsync
MacPorts base version 2.3.4 installed,
MacPorts base version 2.3.4 downloaded.
--->  Updating the ports tree
--->  MacPorts base is already the latest version

The ports tree has been updated. To upgrade your installed ports, you should run
  port upgrade outdated