Update: the normal Darshan download links are now working again.
Our FTP server is down as of 03/29/2018 and we are not yet sure when it will be returned to service. If you need a tar ball with the latest Darshan release, but our normal download links aren’t working, then you can use this link instead:
https://xgitlab.cels.anl.gov/darshan/darshan/repository/darshan-3.1.6/archive.tar.gz
That will generate a tar ball directly from the git repository tag.