- make easier to run server-side. the sysprops to enable com.sun debugging should be cached and then restored —and only set if a -verbose flag is set.
- check for Java Crypto Extensions having full key length; fail fast if not
- list tokens
- add option to check networking (hostname resolves)
- look up KDCs and fail if none are reachable
- maybe each title() call should force flush stderr, to try and keep JDK output in sync with stdout.
- am to have option to display this and also fail fast
- implement `--services` probes for : yarn, hdfs, registry, timeline. This can't go into any hadoop-common lib, a list of probes classes can be provided to execute as the provided UGI.