xavier@xavhome.fr.eu.org (Xavier HUMBERT) writes:

> Actually, if I add 
> 
> ipmon=YES ipmon_flags="s"
> 
> to rc.conf, boot process halts when launching ipmon, until I hit ^C
> Idem if I start it "by hand", `/etc/rcd.d/ipmon start` does not return
> 
> Any workaround other than using a custom start proc ?

As suggested in ipmon(8), add "-D" to ipmon_flags.