From the fping-3.3 Changelog: > * Output statistics to stdout instead of stderr (suggested by Simon Leinen, #9) This breaks smokeping since it expects this data on stderr. My current workaround is a shell wrapper for fping that simply does a 1>&2. Smokeping upstream has been notified, as far as I am aware. We need to either mask fping-3.3 or patch smokeping.
https://github.com/oetiker/SmokePing/commit/491498b57a427230069604d10b68073c0f6f5e33 has a fix for smokeping
2012-09-04 David Schweikert <david@schweikert.ch> * Version 3.4 * Revert "Output statistics to stdout instead of stderr", because it breaks tools assuming the output goes to stderr *fping-3.4 (05 Sep 2012) 05 Sep 2012; Jeroen Roovers <jer@gentoo.org> -fping-3.3.ebuild, +fping-3.4.ebuild: Version bump, fixes bug #433139.