vtun(8) on Linux
The text 1dc9161be584, as Debian 10 (Buster), Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
VTun(Virtual Tunnel) daemon.
Flags it lists
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-4 -
-6 -
-P -
-f -
-i -
-m -
-n -
-p -
-q -
-s -
-t