The sys-apps/net-tools-1.60_p20160215155418 contains typo corrections for netstat's statistics output which breaks the "active" metric for Munin's netstat plugin. https://sourceforge.net/p/net-tools/code/ci/614e15d6f4e32d094288414f6bf086d9761539f8/ I upstreamed the fix to Munin: https://github.com/munin-monitoring/munin/pull/739
This patch is now applied in munin 2.0.33-r1